Tech Tips  thanks for your help Steve

Replacing Your Original Z Seats with 240SX Seats

Things you will need: at least 12 ft of 1/4" x 1" aluminum molding,
hack saw, drill (or drill press if available), tap and die set,
lots of patience, cold beer.

Step 1. Find a good set of 240SX seats in a junk yard. I paid $100
for an immaculate pair. The 240SX seats have "Zip-on, Zip-off"
upholstery that can probably be ordered for replacement if
necessary.

Step 2. Remove the original glide hardware from the 240SX seats. It
will not even begin to fit in your Z. Be careful and replace all of
the bolts you remove to take off the glides. They hold the seat
together You will have to add one more bolt on the "inside" side of
each seat. When you remove the glide, you remove part of the hinge
that holds the top part of the seat to the bottom. The extra bolt
will keep the hinge from shifting (you will see what I'm talking
about if you do it!).

Step 3. Take your original Z seats out of your Z. Take the glides
off the bottom. You will have to retro-fit these glides to the
240SX seat. This can be particularly frustrating since the glides
are held on by very tight phillips head screws. I had to take a
pair of vise-grips and a large screwdriver to break them free.

Step 4. Get at least 12' of aluminum molding 1/4" x 1". You can
pick this stuff up at any Home Depot or Lowe's Home Center. I chose
aluminum because it is much easier to work with. You could use
steel if you had access to the right tools. Measure the width of
the 240SX seats. You want to cut 8 identical pieces of aluminum the
width of the 240SX seat.

Step 5. These next steps will be up to you. I kind of fit
everything as I went along. I measured the distance between the
mount holes on the original Z seats. I drilled holes in the
aluminum that were that distance apart and equal distance from the
ends. This will allow you to bolt the glides to the mounts. For
ease, I tapped these holes so I would not need a nut to hold the
bolt in place.

Step 6. Now that you have the holes drilled in the aluminum slats.
Bolt them to the glides and line them up on the bottom of the 240SX
seat. Square up the glides and mark where holes can be drilled into
metal on the bottom of the seat. Drill the holes through the
doubled aluminum. Then mark where the seats should be drilled and
drill them.

Step 7. Take the glides off of the aluminum slats. Bolt the
aluminum slats to the seats. Be advised, getting the nuts between
the seat metal and the seat foam is hard on the hands. If you
tapped the holes for the seat glides you can now bolt the glides to
the aluminum slats on the seat. It is useful to put a 1/4" spacer
between the slats and the glide for ease of movement.

Step 8. Hopefully, if you were careful to note the alignment of the
glides throughout the process you will be ready to install the new
seats. Place them on the original beams in the passenger
compartment. They should bolt right up. Note, the fit is a little
tight on the door side of the seats. You can do some handy Xacto
knife work on the 240SX plastic seat facing to cover it up.

Step 9. Try seats out. Get comfortable. Drive around. You will
instantly feel better, and your life will immediately improve. Go
home, get the beer out of the fridge and enjoy several cold ones
for a job well done.

Fog Lights For Your 240Z

I have a question concerning my '70 240. Located right above the
hazard light switch on the dash is a "depression "for which I have
no clue of its purpose. I have seen this depression on a '71 240Z
as well.

This "depression" is for a driving lights or fog lights switch that
was available on European and Japanese models.

The US models have the male/female plugs for the driving lights,
wrapped up in electrical tape already in the wiring harness. If you
feel the harness, right along the lower valance pan under the front
bumper (right by the horns) you will feel a "lump" in the harness.
Unwrap the blue tape there, and you will find the "plugs" for the
driving lights.

The switch connectors under the dash. They are wrapped in blue
tape just like the connectors for the fog lights, and are located
in the wiring harness right behind the oil pressure/water temp
gauge. I recently installed some driving lights in my Z. I bought
an automotive toggle switch at Radio Shack, and installed it in the
"depression" hole in the dash. The switch connectors on the factory
harness fit perfectly on the terminals of the Radio Shack
switch.

Then I wired up the lights using the factory connectors and the
original holes under the bumper. Works great, and looks like a
factory installation! Plus, the lights turn off with the parking
lights, so you can't accidentally leave them on all the time.

Tech Tip
Retractable Seat Belts for your 240Z

I would like to put the retracting shoulder/lap seat belts on my
240Z. Can this be done? I assume the later Z's had this feature?

First, some background: The 1970 and '71 240Z's had non-retractable
belts for both lap belt and shoulder belt. The shoulder belt could
be separated from the lap belt and the lap belt could then be used
by itself.

Starting with the '72 240Z's that had a production date of 1/72,
Nissan added a retractable lap belt mechanism. The '73 240Z's also
had the retractable lap belt but the shoulder harness belt remained
NON-retractable, until the 1974 260Z's. However, once you're
buckled in, you generally want the lap belt to stay tight, but when
backing up in reverse, or reaching for the radio, one needs to lean
forward a bit. So, Nissan did it backwards with their first seat
belt retractors in the Z cars!

For the '74 260Z and later Z's Nissan also installed a retractor
for the shoulder strap, along with the lap belt retractor. Unlike
the earlier cars, the lap belt and shoulder belt ends are riveted
together at the buckle. On the '74 and '75 cars the new shoulder
retractor mechanism bolts up right where the original shoulder belt
was attached. The '76-'78 280Z's moved the shoulder retractor
mechanism to the top of the strut tower.

When the lap belts went retractable, a sheet metal "pocket" was
added in the floor pan just in back of the outboard edge of the
each seat to house the belt mechanism. It is interesting to note
that an empty "pocket" was first added to cars with a production
date of 9/71, but the retraction mechanism was not added until
1/72! So, any 240Z produced prior to 9/71 would not have the
pockets for the lap seat retractors. The 1974 260Z's and '75 280Z's
lap belt retractor mechanism is larger, so the pocket in the
floorboard is larger than the '72 and '73 cars.

So, if your 240Z was built between 9/71 and 1/72, you can easily
add the lap seat retraction mechanism from a later '72 or a '73
car. This won't work for the earlier cars as they don't have the
pockets in the floor pan. Although one could cut a couple holes,
and cut the pockets out of a later car, and weld them into the
earlier car, there is an easier solution: Get the seat belts from
a junk '74-'78 2+2 Z car and separate the lap belt from the
shoulder belt by drilling out the large rivet that connects them.
The 2+2's did not have the pockets because if they had them, they
would have interfered with the feet of the rear passengers. Their
mechanism bolts to the bottom side of the rocker sills.

The 2+2 retraction mechanism then bolts to where the '70 and '71
lap belt bolted to. If you also want the retractable shoulder belt,
then get the shoulder belt mechanism from a '74 or '75 2-seater.
Again you must drill out the large rivet at the buckle and then you
can re-join the lap belt to the shoulder belt with a nut and bolt.

Now, if you want to add the retractable shoulder belt to the '72
and '73 cars, again use one from a '74 or '75 2-seater and follow
the same above procedure.

5 speed transmission installation tip:

I just put a 5 speed transmission from a 280Z into my 240Z
without switching the clutches and it now appears that the clutch
is not fully engaging! What's wrong?

The "installed height" of the clutch disc and pressure plate
combination is different between the 240Z and the 280Z. To make
up the difference, Nissan changed the length of the throwout
bearing collar, the piece that the throwout bearing is pressed
into.

Whenever you swap transmissions on a Z car, the safest course of
action is to use the clutch/pressure plate with the throwout
bearing collar that it was originally installed with. In other
words, treat the clutch/pressure plate with the throwout bearing
collar as a "joint" unit. Then you will have no problems. It
sounds likes you did not do this!

I'm afraid that I have no "quick fix" for you. You will have to
drop the tranny (again!) and either use a 280Z throwout bearing
collar or replace your clutch/pressure plate with a 280Z type.

Flywheel

I was wanting a lighter flywheel for my Z, but I was surprised at
the very high cost ($350+) for the Centerforce 13 lb one. Is there
a flywheel weight in between the stock 24 lb and this 13 lb one
that I can use?

Yes there is! The flywheel from the 7/78 to 6/84 production date
Datsun 810's and Maxima's had a lighter 17.6 lb flywheel, part
number 12310-Y7000. So, these are the one's to locate if you're in
search of the lighter flywheel. The 810/Maxima flywheel can be
identified by the "Y70" cast into the backside of the flywheel.

Most junkyards remove the flywheel from engines and will sell them
separately. Just make sure the clutch disc surface is not worn
excessively. Small groves can be machined out. Check for wear on
the starter gear ring. The ring gear can be replaced, but since
this will cost much more than a good used flywheel, avoid getting
a flywheel that needs the ring gear replaced.

The Maxima/810 flywheel takes the 225mm clutch which was the same
size as the 2-seater Z car clutch.

Servicing your AC

It's hot, so hot your Z's dash shimmers. You carefully get into the
car so as not to raise blisters by touching the steering wheel and
you start the engine. You turn the AC on but nothing happens!!
Great, you think, at least in the "old days" ordinary folks could
purchase R-12 refrigerant to re-charge their system, but not
anymore.

Fortunately, it's still possible for the average backyard mechanic
to repair or diagnose most of what ails his Z car's air
conditioning system. Start by acquiring the Nissan factory service
manual for your particular Z and read up on the AC section. It's an
excellent write up. You'll also need a good volt-ohmmeter and a set
of AC gauges. A thermometer is also handy.

No Cooling at All

If the engine driven compressor doesn't engage, there will be zero
cooling. An electromagnetic clutch on the front of the compressor
should lock the drive plate on the compressor with the belt driven
pulley to spin the compressor shaft.

To check the operation of the clutch observe if the compressor
drive plate is rotating when the AC is turned on. The clutch
usually makes an audible "clunk" just as it is engaged. If the
clutch is not engaging, then check the AC fuse to see if it is
blown. If the fuse is blown then replace it and if it blows again
you may have a defective clutch. Measure the resistance of the
clutch coil winding and compare it to the value listed in the
service manual. If your clutch coil measures much below (or much
higher) than what is listed in the manual, then it is probably
defective. It takes special tools to remove a clutch and it's coil
winding. Unless you can rent them or borrow them, leave this job to
a pro.

Connect a test lead from the 12V terminal at the battery to the
blue wire that goes into the compressor. If the clutch does not
engage, then the clutch coil winding is open. Confirm this with a
resistance measurement. If the clutch then engages, you have an
electrical problem.

The electrical circuit consists of a AC compressor relay located in
the engine compartment that is first energized to complete the
circuit to the clutch coil. There is a fuse in this circuit. In the
AC relay circuit there is a micro switch activated by the AC
control lever, a "low pressure" cut out switch, and a thermostat
switch that cycles the compressor to regulate the temperature. In
addition, the interior blower fan must be turned on in order for
the circuit to work. So, there are a lot of possibilities for an
electrical problem which you can troubleshoot yourself with a volt-
ohmmeter.

However, the refrigeration system may also be involved. The low
pressure switch located in the receiver/dryer unit is designed to
keep the compressor from engaging when the freon pressure is low.
Unplug the wiring connector from this switch and use the volt-
ohmmeter to see if it is closed.

If the switch checks open, then connect the AC gauges to the
Schrader valves to measure the freon pressures in the system.
Remember, the "high" side (or "discharge" side) of the compressor
connects to the red gauge, and the "low" side (or the "suction"
side) of the compressor connects to the blue gauge. After the
system has been off for a few minutes, the high and low side
pressures equalize and the system pressure is a function of the
ambient temperature. If the pressure is less than 35psi, then the
system is low on freon and needs a re-charge. Proceed to the re-
charging section. However, the reason the system is low on charge
is probably due to a leak.

Now the best way to find a leak is to pressurize the system with
freon and use a leak detector. However, sometimes a leak can be
spotted visually. There is oil mixed in with the freon to lubricate
the components in the system, and when you have a leak this oil can
be seen. Usually the oil attracts a coating of dirt so look for a
"dirty oil-soaked" stain. Some areas for leaks include the
condenser (damage from road debris), loose hose fittings and a
leaky front compressor seal. Incidentally, if the Schrader valve
caps are missing, they could be the cause of your freon loss, as
they provide the real seal, and not the valve itself.

Poor Cooling

If there is some cooling, but clearly not a normal amount, then
there are a few initial checks you can make. Is the condenser free
of bugs, leaves or road dirt? If it isn't, then airflow is
restricted. Clean the condenser with a soft brush and a detergent
and water solution.

The engine radiator fan and or an electric supplemental radiator
fan may be defective, reducing the air flow across the condenser
coils, although this usually results in engine overheating as well.

It is possible that the heater core is circulating hot water
because of a leaky or stuck open watercock valve. Use a pair of
vice-grips to squeeze off the heater core supply hoses in the
engine compartment to check for this.

However, the majority of the time a case of poor cooling is a
result of a low level of freon in the system. The receiver/dryer
unit has a "sight glass" on it's top to allow a look inside the
system. With the AC turned on, check the sight glass for bubbles.
A continuous flow of bubbles means the system probably is low on
charge. No bubbles can either mean no charge or too much charge.
You have to put the AC gauges on to correctly verify the state of
the charge.

Because of the nature of AC systems, the readings on the gauges for
a fully charged system are a strong function of the outside ambient
air temperature and the relative humidity. There is a chart in the
service manual to assist you. For example, a 1974 260Z at a
relative humidity level of 70% has the following measurements:

Outside Air Discharge Air High Side Low Side
Temperature Temperature Pressure Pressure
(degs F) (degs F) (psi) (psi)

70 49 to 55 154 to 182 24 to 33
80 57 to 64 168 to 202 28 to 37
90 63 to 71 192 to 228 34 to 43
100 70 to 78 219 to 255 43 to 51

The discharge air temperature is measured by inserting a
thermometer into one of the ducts. Make your measurements at the
maximum cold setting and at the highest interior fan speed. The
engine should be at a fast idle, 1,500 rpm or so.

If the high side pressure is lower than what the chart says, then
there is an insufficient amount of freon in the system. If you were
lucky enough to have obtained so cans of R-12 freon before it
became illegal to buy without a license, you can add some to your
system. With the gauges connected to the appropriate Schrader
valves, attach the center hose to the can of R-12 using the adaptor
that pierces the top seal on the can. A tip to speed up the
recharging process is to immerse the can of R-12 into a pan of warm
water.

With the engine running and the AC on, open the low side valve to
allow the freon to flow from the can into the system. Keep a eye on
the sight glass and when the bubbles cease to be visible, stop the
recharging. Do not over fill, as this will reduce the cooling
capability of the AC system. If one can of freon is not enough,
then another can be started. When completely empty, the system will
hold two of the one-pound cans of freon.

Other Problems

Poor AC cooling can be caused by the cooled air not flowing out the
correct duct in the passenger compartment. It's much more effective
to have the cold air blowing in your face, and not at your feet or
going through the defroster ducts.

Z cars use a vacuum system to operate the various air control vent
doors. The vacuum is generated by the engine and a one way check
valve and stored in a plastic bottle in the engine compartment. An
electrical solenoid directs the vacuum flow. Early Z cars are
notorious for engine compartment vacuum hoses that crack due to age
and heat. A bad check valve can allow the system to work at idle
speeds, when you have a large vacuum in the intake manifold, but as
the throttle is depressed, the intake vacuum goes away and the
vents stop working.

The interior blower fan speed may not be high enough. Leaves and
other debris (I once found a mouse's nest in there!) can enter the
blower intake and reduce the air flow. Resistance at the fan motor
electrical contacts can reduce the voltage across the blower motor.
Check all the electrical connections between the battery and the
fan for any excessive voltage drops, including the fuse and fusible
link.

Check the condition of the ductwork seal between the output of the
blower housing and where it joins the diffuser section behind the
evaporator. This seal tends to dry out over the years.

The AC compressor belt adjustment pulley has a bearing that can
seize and not allow the compressor to rotate. This is a common
problem on high mileage Z cars. Keep on eye on this adjustment
pulley and replace it if it starts to become noisy.

A Final Word

Don't expect the '70-'78 Z car AC systems (factory or dealer
installed) to preform miracles. The later 280ZX and 300ZX systems
are much better performers. If your AC system is working overtime,
and you're still sweating it out, consider window tinting, it
really helps. Also, increases the thickness of the floor and
transmission tunnel carpeting (or even adding some there) helps to
keep unwanted heat from entering the passenger compartment.

What to look for when buying a battery.

Cold Cranking Amps

The most important consideration is the battery's Cold Cranking
Amps or CCA rating. CCA's are the discharge load measured in amps
that a fully charged battery at 0 degrees F can deliver for 30
seconds and while maintaining the voltage above 7.2 volts.
Batteries are sometimes advertised by their Cranking Amps (CA)
measured at 32 degrees or Hot Cranking Amps (HCA) measured at 80
degrees, which are not the same as CCA. Do not be mislead by CA's
or HCA's. To convert CA's to CCA's, multiply the CA's by .8. To
convert HCA's to CCA's, multiply HCA's by .69. In hot climates,
buying batteries with double or triple the CCA ratings that exceed
the OEM (original equipment manufacturer) requirement is a WASTE of
money. However, in colder climates the higher CCA rating the
better, due to increased power required to crank a sluggish engine
and the inefficiency of the cold battery.

Reserve Capacity

The next most important consideration in buying a battery is the
Reserve Capacity (RC) rating because of the effects of an increased
parasitic or "key off" load produced by electrical devices, e.g.,
fans, clocks, computers, etc., that operate after the engine is
stopped. RC is the number of minutes a fully charged battery at 80
degrees F can be discharged at 25 amps until the voltage falls
below 10.5 volts. More RC is better in every case. For example, if
your car has a 360 OEM cranking amp requirement, then a 450 to 500
CCA rated battery with 120 minute RC would be more desirable in a
warm climate than one with 700 to 800 CCA with 90 minutes of RC.

Type

A sealed or "maintenance free" battery will NOT allow you to test
the specific gravity with a hydrometer or add DISTILLED water when
required. Sealed batteries are more prone to deep discharge
failures, but require less preventative maintenance. Car batteries
are specially designed for high initial cranking amps (usually for
five seconds) to start a car; whereas, deep cycle or "marine"
batteries are designed for prolonged discharges at lower amperage.
A "dual marine" battery is a compromise between a car and deep
cycle battery. However, a car battery will give you the best
performance in a car. Some manufactures have introduced a "dual"
battery that combines a standard battery with emergency backup
cells.

Physical Size

Manufacturers build their batteries to an internationally adopted
BCI group number (24F, 35, etc.) specification, which is based on
the physical case size, terminal placement and terminal polarity.
The OEM battery group number is a good starting place to determine
the replacement group. Within a group, the CCA and RC ratings,
warranty and battery type will vary in models of the same brand or
from brand to brand. Batteries are generally sold by model, so the
group numbers will vary for the same price. This means that for the
SAME price you can potentially buy a physically larger battery with
more RC than the battery you are replacing. Be sure that the
replacement battery will fit, the cables will correct to the
correct terminal, and that the terminals will NOT touch the hood
when closed.

The battery manufacturers publish application guides that will
contain the OEM cranking amp and group number replacement
recommendations by make, model and year of car, and battery size,
CCA and RC specifications. Manufacturers might not build or the
store might not carry all the group numbers. To reduce inventory
costs, dual terminal "universal" batteries that will replace
several group sizes are becoming more popular. The four largest
domestic battery manufacturers are Johnson Controls (Interstate,
Motorcraft, Energizer, older Diehards), Delco (Sears, newer
Diehards), GNB (Champion) and Exide (NAPA).

Age

Determining the "freshness" of a battery is sometimes difficult.
NEVER buy a battery that is MORE than SIX months old! The date of
manufacture is stamped on the case or printed on a sticker. It is
usually a combination of alpha and numeric characters with letters
for the months starting with "A" for January (skipping "I") and
digit for the year, e.g., "F5" for June, 1995. Like bread, fresher
is definitely better.

Tech Tip

Is it possible to remove the cam towers from the cylinder head and
re-install them without having to worry about alignment? The
service manual says that this is a "no-no".

The locator sleeves between the head and the cam towers do a fine
job of getting the towers lined up again. In fact, if you look at
a head that has been shaved or milled, it should have correction
plates/shims that are inserted under the towers to ensure that the
timing chain "slop" remains within spec. Depending on how much you
mill, it would be difficult to take up all the slack with the chain
tensioner.

The key to installing the towers is to install the cam AND towers
together. Then go through steps in torquing the bolts which secure
the cam towers to the head, so all the towers are torqued evenly.
Starting with a low torque setting, and follow a couple more times,
increasing the torque setting each time, checking for smooth, light
cam rotation. If necessary, tap the bearings with a mallet to
smooth things out, then repeat the procedure until the cam tower
bolts are torqued to spec, and the CAM TURNS FREELY! Install the
cam followers to finish the job.

The How to Modify your Nissan/Datsun book by Frank Honsowitz
recommends the above method.

What are the symptoms of a clogged catalytic converter?

The most noticeable symptom will be a lack of power. You step on
the gas and your Z car doesn't get up and go. A badly plugged
converter may not even let the vehicle go over 30 mph. The
converter will be hotter on it's intake side if it is plugged and
may even glow a dull red if the engine has been running a while.

Here's the simple procedure for testing for a clogged catalytic
converter

1. Connect a vacuum gauge to a vacuum line fitting on the intake
manifold. The easiest access points are either the off the vacuum
fitting going to the brake booster check valve or the vacuum hose
fitting for the charcoal canister purge valve.

2). Record vacuum at idle (usually over 17 inches of Hg).

3). Record vacuum at 3000 rpm with engine at no load.

4). The vacuum reading taken in step 3 should be at least as great
as that taken in step 2. If the vacuum reading in step 3 starts
dropping (even going positive) from its original reading, then you
could have a clogged converter.

This is an indirect test -- a better one is to use a backpressure
tester. This is a vacuum/pressure gauge with an adaptor which
allows the tester to be screwed into the oxygen sensor's socket.
At 3000 rpm, the backpressure should be below 3 psi. You can buy
these at your local automotive parts place for $25-30.

Tech Tip
Finding Coolant Leaks

When it comes to coolant leaks, do the common sense stuff first.
For example, monitor the level and activity of the coolant
reservoir. When the engine cools down, the low pressure in a tight
cooling system should draw coolant in from the reservoir. What's
more, the reservoir coolant level on a hot engine should be
consistent if the cooling system is leak free.

Locating a small leak can be difficult because the coolant often
evaporates as soon as it leaks out. Pressurize the system with a
hand operated pressure checker and give it a thorough visual
inspection. It could take a while for a pinhole to create the
telltale stains you search for during diagnosis.

Hunting for leaks with a hand operated pressure checker can be time
consuming because you have to keep pumping the thing up to maintain
pressure on the system. Pressure testers that rely on shop air
eliminate manual pumping, allowing you to keep your eyes focused on
suspected leak points. Wear protective goggles when hunting for
coolant leaks.

Remember that checking the system cold may reveal a leak you can't
find when the system is hot. It's well known that problems such as
leaking water pump seals are more likely to occur when the engine
is cold.

Adding a fluorescent leak-detection dye to the coolant is the most
accurate way to locate elusive external coolant leaks, including a
seeping water pump concealed by other engine components. Leak
tracing dye also is a great quality control tool because a dye
check after a repair is completed shows you that the troublesome
leak is finally fixed.

Note three details about the dye method: First, you must clean up
existing dye stains before retesting. If you don't, you won't know
if you're looking at a recurring leak or dye lingering from the
previous leak. Some techs just use solvent for this task. As of
this writing, one manufacturer (Tracer Products) offers a water
based, nontoxic spray cleaner for removing fluorescent dye.

Second, you need a UV (ultraviolet or "black light") lamp to spot
fluorescent dye. The more powerful the black light, the easier it
is to see dye traces on a dirty engine inside a dark engine bay.

Third, UV lamps are fairly large and tough to maneuver inside a
crowded engine compartment. Today, at least one compact, flashlight
size UV light (Tracer Products again!) is available for automotive
leak detection.

The ease of pinpointing a coolant/combustion leak depends on the
severity and location of the leak. Begin by checking for pressure
buildup inside the coolant reservoir and/or a persistent sweet odor
of antifreeze in the exhaust.

Comparing spark plugs can help flag an internal coolant leak. Look
for a plug that's noticeably cleaner than the others with no carbon
deposits on it, with the porcelain around the center electrode
looking almost spotless. Inspect the combustion chamber that spark
plug came from with a small dental mirror and a shop light. You'll
find the chamber also looking unusually clean due to the steam
cleaning action of the coolant leak.

Antifreeze in the exhaust taints the oxygen sensor, turning the tip
of the sensor green or a grainy, brownish white color. Eventually,
leaking coolant also can contaminate and clog a catalytic
converter.

Looking for combustion gas bubbles inside the radiator can be
misleading. It's easy to mistake air venting or even a sticking
thermostat for combustion bubbles.

Connecting a coolant pressure gauge to the radiator neck can
confirm a coolant/combustion leak. Cooling system pressure should
remain fairly stable as you rev the engine. Pressure readings that
either climb or drop into a vacuum when you snap open the throttle
suggest cracks in the valve seat area.

Finally, you can pressurize each cylinder with compressed air and
see if bubbles appear in the radiator. If you use this air check,
remember that some leaks are more noticeable when the engine is
cold.

Tech Tip

Why does the interior of my early Z car smell like exhaust fumes? It's
especially bad with the windows open?

As a car is moving down the road with the windows up but with the vents open,
the air pressure in the passenger compartment tends to increase. This is
because the vents are in front of the radiator, which is a high pressure area.
If the windows are rolled down this pressure is reduced and may even be
slightly negative. This lack of pressure "allows" the exhaust gases to enter
the passenger compartment by any opening they might find.

The usually place of entry is the rubber rear hatch seal. These tend to lose
their seal over the years. The solution here is to buy a new one.
Unfortunately, the rear hatch seal is very expensive, so you may be able to
adapt a similar sized generic weatherstrip.

Don't overlook other possible leaks: The openings where the fuel tank vent
lines go through the body of the car. Silicone these if they look suspect.
Also, the gaskets on the rear taillights can leak, allowing fumes to enter.
Replace them or use silicone if your a cheapskate.

Another possible leak is the gear shifter boot. Pull the console out to check
this. Also, you can seal up the rear hatch latch mechanism from the passenger
compartment. Make a gasket from some flexible plastic material and silicone it
around the latch.

If all these suggestions fail, then you can try extending the exhaust tailpipe
by some six to ten inches past the bumper. You can even angle the exhaust
tailpipe to the left, away from the car, as this also seems to help.

Tech Tip
Flushing Your Cooling System

You take off the radiator cap and look at the coolant. It's usually
a nice shade of green, but nowadays you can find red and maybe even
orange or bronze tinted fluid. Well, it looks good. So, should you
leave it in? Unless it's colored orange or bronze stuff, the answer
is NO! Especially if it's been two years or more since the last
time you drained it.

Z car engines are loaded with aluminum components: cylinder
head(s), water pumps, front engine covers, manifolds, heater cores
and even some of their radiators. Aluminum needs great corrosion
protection to survive, and the corrosion protection in the green
and red colored antifreeze is used up in about two years. However,
the orange or bronze colored coolant does offer longer life. More
on that, later.

Draining the Coolant

Start by checking your service manual to see how much fluid is in
your system. This is important, because Z cooling system capacities
varied depending on the generation. Also, if you have increased the
size of your stock radiator (e.g., from a three core to a four
core), you will have to account for this.

Be safe and start with a cool engine. Set the interior heater
control lever to the HOT position. This will allow the heater core
to drain. If you have a radiator overflow reservoir, then remove it
and drain it as well. Now remove the radiator pressure cap and open
the radiator drain cock. You can use a pair of pliers to reach a
difficult-to-reach one (like on the 300ZX's) or to free a stuck
one, but be careful. Remember, the Nissan drain cocks are made of
plastic, so they're easy to break!

If the drain cock is really stuck, or broken off flush with the
bottom of the radiator, then you can disconnect the lower radiator
hose from the radiator to drain the coolant.

Let the used coolant drip into a container or pan. If your house
has a city sewer disposal system, then you are allowed to empty
your old anti-freeze into your drain. Don't just pour it on the
ground or into a septic tank system. Better yet is to take it to
one of the hazardous waste disposal facilities in your are, or you
can nicely ask a auto repair shop to dispose of it.

Draining the radiator alone will only remove about half of the
coolant. There is an engine drain plug located on the side of the
block. Removing this will allow the remainder of the coolant to
escape. It's messy, but it's the preferred way.

Refilling

First, tighten the drain cocks and any hoses you may have removed.
Check on the side of the new container of antifreeze for how much
antifreeze you actually need. Now most people just put the
"standard" 50/50 (half water and half antifreeze) ratio back in
their system, but I recommend using only as much antifreeze as
necessary. The reason for this is the fact that water by itself is
a much better conductor of heat than antifreeze!

It is generally recognized that straight water will cool a car more
effectively than any combination of water and antifreeze, despite
antifreezes marginal increase in boiling temps. So, the old adage
of "if some is good, then more is better" does not apply with
respect to antifreeze. There will still be plenty of anti-corrosion
inhibitors and water pump lubricant even with a 20% ratio of
antifreeze.

What about using distilled water with the antifreeze instead of
ordinary tap water? The reasoning here is that normal tap water has
minerals dissolved in it. Through repeated heating in your car's
cooling system, those minerals will eventually precipitate and form
hard deposits in the radiator, especially in small passages.
Distilled water is free of minerals, and therefore will not have
this effect.

However, now the reasoning is to use regular tap water because
water normally likes to have ions floating around. If it doesn't,
then it gets them from wherever it can. Aluminum readily ionizes,
so the distilled water "steals" the ions from the aluminum
components and they corrode. If you use tap water, it is "pre-
ionized", so to speak. The tap water will sacrifice itself, and not
your engine parts, to the chemical reactions created during thermal
cycles of the fluid and metal parts.

The cooling system has nooks and crannies that can trap air. The
filler neck is supposed to be at the high point to let air out, and
there is a small hole in the thermostat to allow trapped air to
escape. Fortunately, Z cars are not known to be hard to refill with
coolant and air pockets generally do not occur.

Slowly pour the antifreeze and water into the radiator until it is
full. Now you probably won't completely fill the system initially.
Start the engine and let it idle until the thermostat begins to
open. The water level in the radiator will invariably go down. Add
some more water or antifreeze until it is full. Remember only add
water to a hot engine while it is running! Better still is to warm
the engine with the radiator cap on, let it cool and then check the
fluid level. Check the fluid level periodically over the next
several days.

Which Antifreeze To Use?

Most antifreeze is made with a colorless base chemical called
ethylene glycol. A green dye is used in most brands, although there
is a Toyota brand which is red. The latest entry into the market
are the "long life" types of antifreeze which are tinted orange or
bronze (e.g., Prestone Long Life 5/100, or 4/60). These are good
for four to five years.

If you are changing from the "green stuff" over to one of the long
life antifreezes, then you must thoroughly flush out your cooling
system first. The corrosion inhibitors in the green and the
orange/bronze antifreezes are not compatible. After you have
removed the green antifreeze put back in only water. Let the water
circulate. Let the engine cool and re-drain the water. Repeat this
twice more.

It's a good idea to make sure that the antifreeze is a "low
phosphate" type. The presence of phosphate in your coolant will
force the concentration of aluminum ions to be extremely low. This
will tend to increase the rate at which aluminum metal components
of the engine will oxidize (corrode) into the coolant.

The aluminum phosphate formed will tend to collect in your cooling
system and will NOT flush out. This could impair the efficiency of
heat transfer and reduce water flow rates through the system.

So to be safe, use a phosphate free coolant. Read the label on the
antifreeze container. If it says "phosphate free", it should be OK.
If it says "safe for aluminum engines", it should also be OK. If it
doesn't make one of these claims, then find another variety.

What about the "pet-friendly" antifreezes? These use a base of
propylene glycol and will do the same job as ethylene glycol. They
cost a little more and require a greater quantity to provide the
same protection and they're really only a bit less hazardous. Their
real claim is that they don't have a "sweat" odor or taste (I
wonder who found this out!) and therefore are less likely to attach
pets or small children.

Tech Tip:
Repairing your 240Z Fuse Box.

A problem with early Z car electrical systems is the development of
resistance in the fuse box which can lead to melted spots in the
plastic fusebox, blown fuses, melted wires, and possible shorts in
the wiring harness. The areas that usually go first are the
circuits that carry the highest amperage, the lights and amp gauge,
because they experience the highest heat dissipation across the
resistance.

When the fuses blow, they only open at one end of the fuse, rather
than across the center of the fuse. The clip which holds the fuse
gets extremely hot, and melts the connection between the fuse
element and the end of the fuse. It is not caused by having too
much current in the circuit.

This condition is very easy to diagnose. Lift your ashtray/fuse box
cover, pull the clear plastic fuse box cover off, and briefly touch
the fuse clips with that particular circuit on for a few minutes or
so. If it's too hot to leave your fingertip on it, you have a
problem.

The fuse clips are brass, and the terminal rivets appear to be
steel. They are not soldered together, but depend upon metal to
metal contact. These are "dissimilar metals", and corrosion starts
working between the rivet head and the fuse clip. Corrosion =
resistance = heat, hence melting plastic and melting at the ends of
the fuse internally.

The fuse box can be replaced but it makes sense to try to repair
them because the cost of a new one is anywhere from $80-$100.

If the plastic is still in fair shape in the fuse box, one can fix
the problem by removing the fuse clips contacts by using a small
screw driver to depress the little barbs on the sides of the clips
and the push them out the back of the fusebox. This enables you to
clean and solder the clips to the rivets without melting the
plastic. Repairs to the plastic base can be made at this time using
JB Weld epoxy. JB Weld has a high melting temperature, much higher
then the original plastic. The tension that the fuse clips have is
also important, so carefully reform the clips so that they firmly
hold the fuse.

If the plastic base is in bad shape, you can "bypass" the fuse box
by using a 20 amp rated external fuse holder spliced into the
particular circuit. The external fuse holder can then be hidden
nicely behind the fuse box.

240Z Heater Problems

I have a 1970 240Z and the interior heater is starting to make me
mad. The heater will only work for about two minutes after the car
warms up, then it blows cold air. Is this a bad heater core or
what?

Some likely causes of your problem are:

1. The cables that come out of the back of the heater control
become disconnected at one or both ends. Or the clamp clips that
holds down the plastic part of the cable do not grip properly
causing it to slip back and forth, thus preventing the cable from
moving the various flaps that redirect hot and cold blower air.
Also make sure that none of your cable wires are crimped or broken.
It is not unusual to find the above problems on an older 240Z.

2. The heater core becomes plugged with corrosion and engine rust
deposits. Sometimes "back flushing" the heater core from the engine
firewall side with a garden hose (in the opposite direction of
normal water flow) will help.

3. If you can not get much flow through the core when back flushing
with the hose in either direction, and you get moisture
condensation on the inside of your windshield when you open the
heater core valve on a cold day or if you smell hot coolant in the
car, then it probably means that you have a bad heater core.

4. Finally, check your inlet valve to the heater core. Over time
they cease to work properly and may become stuck in a closed
position during the summer months. They are a bear to replace, so
use a new one if you do.

Tech Tip

What do the numbers and letters in a motor oil designation mean?

There are several different items encoded. There is a two-letter
code indicating the type of detergent package that the manufacturer
uses in the oil; this looks like SE,SF,CD or such. The S codes are
for gasoline engine applications; the C codes are for diesel engine
applications. The second letter is assigned in sequence as new
levels of protection are developed; thus SF is considered better
than SE, SE is considered better than SD, and so forth.

The more noticeable designation is the oil weight. This is either
a single number (e.g., 30 weight) or a pair of numbers separated by
the letter W (e.g., 10W30.) The latter type is much more commonly
used these days, and are the only type that most automobile
manufacturers specify in operators manuals. The first number in the
designation (10W) is the apparent viscosity of the oil when it is
cold; the W stands for `winter'. The second number (30) is the
viscosity of the oil when hot. There is a trick here; the oil
doesn't actually get thicker (turn from 10 weight to 30 weight) as
it gets hotter. What is actually happening is that when the oil is
cold, it has the viscosity of a cold 10 weight oil. As it gets
hotter, it doesn't get thin as fast as a 10W oil would; by the time
it is up to temperature, it has the viscosity of a hot 30 weight
oil.

Note that these numbers actually specify ranges of viscosities; not
all 10W oils have exactly the same viscosity when cold, and not all
30 weight oils have the same viscosity when hot. Note also that the
novel behavior of multi-grade oils is caused by additives, and it
has been reported that with the sole exception of Castrol GTX,
10W40 oils do not retain their multi-grade characteristics well
over time. 10W30, 15W40, and 20W50 oils work very well, though.

Engine Overheating Tips

1. Safety reminders before starting: Never open the radiator cap on a hot engine. Wear safety goggles to
prevent antifreeze from splashing in your eyes. Keep your hands and clothing away from spinning fans.
Remember that some electric fans may operate after engine shutdown.

2. Check for obvious problems first. Loss of coolant because of a leak is probably the most common
cause of overheating. Possible leak points include the hoses, the radiator, heater core, water pump,
thermostat housing, coolant reservoir, head gasket, freeze (or core) plugs, automatic transmission oil
cooler, and cracks in the cylinder head(s) and block.

Checking for the presence of combustion products in the cooling system is the recommended procedure
to determine a cracked head or block. If the leak is bad enough then bubbles will be visible in the radiator
while the engine is running.. A simple compression check might also point to the same conclusion.

3. Make a careful visual inspection of the entire cooling system. Check belt tension and condition. A
loose belt that slips may prevent the water pump from circulating coolant fast enough and/or the fan from
turning fast enough for proper cooling. The condition of the hoses should also be checked. It is
recommended to replace the hoses if they are more than five years old. Sometimes a lower radiator
hose that has softened will collapse under a vacuum at high speed and restrict the flow of coolant from
the radiator into the engine.

4. Attempt to better diagnose the problem. When a car overheats after only a few miles of driving, then
suspect a thermostat stuck closed. If it gradually overheats only at idle suspect a faulty fan. If it
overheats gradually as it's being driven at steady speeds, suspect the water pump. If the engine
overheating gets worse during higher speed operation, then a plugged radiator or a plugged cooling
system are primary suspects.

5. Remove the radiator cap and pressure test the system at the radiator. A pressure test will reveal
internal leaks such as seepage past the head gasket as well as cracks in the head or block. A leak free
system should hold 15 psi for at least two minutes or more. Start the engine and check to see if the
system builds up adequate pressure as soon as the thermostat opens, and that the pressure continues to
build as you rev the engine.

It's important to pressure test the radiator cap because a weak cap (or one with too low a pressure rating
for the application) will lower the coolant's boiling point and can allow coolant to escape from the
radiator.

6. Remove and check the thermostat. Severe overheating can often damage even a new thermostat. If
the engine has overheated because of another problem, then the thermostat should be tested or
replaced before the engine is returned to service.

One way to check the thermostat is to start the engine and feel the upper radiator hose (or use an
infrared non contact thermometer to read it's temperature). The hose should not feel uncomfortably hot
until the engine has warmed up and the thermostat opens. If the hose does not get hot, it means the
thermostat is not opening.

Another way to test the thermostat is to remove it and place it into a pan of boiling water (it should open).
The exact opening temperature can be checked by using a thermometer.

If the thermostat needs to be replaced, install one with the same temperature rating as the original. Using
a cooler thermostat in an attempt to "cure" a tendency to overheat can increase fuel and oil consumption,
ring wear and emissions. On newer vehicles with computerized engine controls, the wrong thermostat
can prevent the computer system from going into closed loop resulting in performance and emission
problems because the engine fails to reach its normal operating temperature.

7. Overheating at idle can also be caused by insufficient airflow past the radiator. With mechanical fans,
most overheating problems are caused by a faulty fan clutch although a missing fan shroud can reduce
the fan's cooling effectiveness, which may be enough to cause the engine to overheat in hot weather or
when working hard. If a shroud is loose or was damaged and not replaced, it can be a contributor to
overheating. While you're inspecting the fit of the shroud, also look at the condition of the perimeter
seals around the condenser and radiator.

Defective fan clutches are a common and often overlooked cause of overheating. The shear
characteristics of the clutch fluid gradually deteriorates over time. Eventually slippage reaches the point
where effective cooling is no longer possible and overheating results. Look for a fan clutch that's running
too slow when the engine is running hot. Typically, clutch fan speeds peak at around 2000 to 2200 rpm,
and you can use a photocell tachometer with some reflective tape to check for a slipping clutch
condition. Rule-of-thumb is the life of a fan clutch is about the same as a water pump. If one needs to be
replaced, the other usually does too.

If the fan clutch shows signs of fluid leakage (oily streaks radiating outward from the hub of the clutch),
spins freely with little or no resistance when the engine is off or wobbles when the fan is pushed in or out,
it needs to be replaced.

With an electric cooling fan, check to see that the fan cycles on when the engine gets hot and when the
air conditioner is on. If the fan fails to come on, check the fan motor wiring connections, relay and
temperature sensor. Try jumping the fan directly to the battery. If it runs, the problem is in the wiring,
relay or sensor. If it fails to run, the fan motor is bad and needs replaced.

8. Check the water pump. Any wobble in the pump shaft or seepage would call for replacement. In some
instances, although rare, a pump can cause an engine to overheat if the impeller vanes are badly eroded
due to corrosion or if the impeller has come loose from the shaft. The wrong pump may also cause an
engine to overheat. Some engines with serpentine drive belts require a special water pump that turns in
the opposite direction of those used on the same engine with ordinary V-belts.

So how can you tell if the system is flowing enough coolant? One way is to install a special tester, such
as Hickok's Radicool, in series with the upper radiator hose and compare the flow with the rate in the
manual (about 6 gallons per minute for engines less than 2 liters to more than 20 gallons per minute for
big V8's).

If there's any reason to believe that the block may be plugged and could benefit from a flushing, then do
it.

9. Check the radiator. The most common problems radiators fall prey to are clogging (both internal and
external) and leaks. Dirt, bugs and debris can block air flow through the core and reduce the radiator's
ability to dissipate heat. Internal corrosion and an accumulation of deposits can likewise inhibit coolant
circulation and reduce cooling. A good way to find clogs is to use an infrared thermometer to "scan" the
surface of the radiator for cold spots. If clogged, the radiator should be removed for cleaning or be
replaced. Back flushing the cooling system and/or using chemical cleaners can remove rust and hard
water scale from the engine block, but do little to open up a clogged radiator.

If coolant flow is a question, you have to check the radiator separately. The most practical way is with a
tapered cone rubber adapter that attaches to the radiator inlet neck and accepts a water hose. If you feed
in a solid column of water and all that comes out the other neck is a trickle, then the radiator is obviously
plugged.

10. Other causes, although rarer, of overheating include:

Excessive exhaust back pressure. A clogged catalytic converter is usually the culprit here, but don't
overlook the possibility of a crushed exhaust pipe. Check intake manifold vacuum at idle. If it reads low
and continues to drop as you slowly rev the engine then inspect the exhaust system.

Retarded or over advanced ignition timing (may also contribute to detonation and pre-ignition).

Overheated incoming air. On vehicles with a carburetor or throttle body injection, check the operation of
the heated air intake system on the air cleaner. If the temperature control valve is stuck so only heated
air from around the exhaust manifold is drawn into the air cleaner, it may contribute to detonation and/or
overheating. Also check the heat riser valve for manifold heat on older V6 and V8 engines. If stuck shut,
it may be overheating the intake manifold.

Overworking the engine. The cooling systems in many vehicles are marginal and have little excess
capacity to handle the extra heat generated by towing or high speed mountain driving in hot weather.
A brake caliper that's sticking or a parking brake that isn't releasing may be making the engine work too
hard as well.

11. When refilling the cooling system, be sure you get it completely full. Air pockets in the head(s),
heater core and below the thermostat can interfere with proper coolant circulation and cooling. If the
cooling system has no bleeder valves to vent air, you may have to temporarily loosen a heater hose to
get all the air out of the system. Remember never add coolant to a hot engine unless the engine is
running.

Pure water is unequivocally the best coolant. Use only the minimum amount of antifreeze required for
your climate. But add a corrosion inhibitor such as Prestone's Super Anti-Rust.

Paint Care FAQ

What is Factory Applied (OEM) Paint?

This is the paint applied to a vehicle at the Original Equipment Manufacturer's (OEM) factory.

What is Fresh Paint?

This is a term used to describe "refinish paints" (paints used in automotive body shops) that have not fully cured.
Refinish paints are deemed fresh for 30 days after their application. Most paint manufacturers do not recommend
applying a wax to fresh paint.

What is Cured Paint?

This refers to all automotive paints applied at the factory, and refinish paints that are more than 30 days old. Wax is
recommended for application only to cured paints.

What is a Clear Coat Paint?

Clear coat paint refers to the clear (non-pigmented) top coat paint that is applied over a colored base coat paint, and
is found on most vehicles built in recent years. Clear coat paint increases the vehicle's paint durability, gloss and
resistance to harmful environmental effects. Most car care products that are recommended for use on clear coat paint
are clearly marked "clear coat safe."

What is a Single Stage Paint?

Single stage paint refers to the pigmented, or colored, top coat paint applied to most older vehicles and some new
vehicles. Single stage paints do not have a clear top coat. However, car care products that are marked "clear coat safe"
may also be used on single stage paints.

What is Oxidation?

Oxidation is the dulling and/or hazy appearance of a vehicle's paint caused by weathering from outdoor exposure.
Correction requires the removal of the oxidized layer of paint by using a cleaner wax, polish, or rubbing compound,
depending on the degree or severity of the oxidation.

What is "Orange Peel"?

"Orange peel" is a term representing the texture of a painted surface that has "hills and valleys" or bumps similar to the
skin of an orange. Excessive orange peel is generally considered a paint condition defect.

What is a Swirl Mark?

A swirl mark is a curved, minor scratch left in the painted surface by a rubbing compound or a wool buffing pad. Swirl
marks can be removed from the paint surface by using a polish or wax.

What are Polishes?

Polishes are specifically formulated blends of oils, solvents, water and minerals that are designed to remove minor paint
surface imperfections such as fine scratches, light oxidation, water spots and swirl marks left from rubbing compounds.
Polishes may , or may not, contain waxes or silicones. Polishes create a deep, rich, swirl-free finish, and can be applied
either by hand or machine.

What are Glazes?

A glaze is a polish that is safe for use on fresh paints. Glazes also have varying degrees of aggressiveness. Glazes,
used either by hand or machine, will remove minor paint surface imperfections. It should be followed either by a wax
on cured paint or by a hand glaze on fresh paint. Hand glaze does only minor polishing, and its primary use is to
enhance surface gloss and luster on fresh paints. It needs to be re-applied frequently until the paint is cured and can
be waxed.

What is Silicone?

Silicone is a chemical polymer that has excellent water repellency and a very slippery feel. Silicones are commonly used
in automotive waxes to enhance the application and ease of removal, and to increase gloss and durability.

What are Rubbing Compounds?

Rubbing compounds are specifically formulated suspensions of oils, solvents, water, and minerals produced in either
a liquid or a paste construction. They are designed to remove paint surface imperfections such as scratches, oxidation,
stains, and acid rain etching. Rubbing compounds can be applied either by hand or machine.

What are Waxes?

Waxes are uniquely formulated blends of wax, polymers, glossifiers and other ingredients that protect and produce a
durable, ultra-high gloss finish. Waxes make it easier to clean (wash/dry) the paint surface. Some waxes also serve
as polishes, and are capable of removing minor paint imperfections.

What are Cleaner Waxes?

Cleaner waxes are wax/polish combinations. They contain mild abrasives that are capable of removing minor paint
imperfections, as well as wax and other ingredients that produce a durable, high- gloss finish.

What is the Difference Between Rubbing Compounds and Cleaners?

There is little difference between rubbing compounds and cleaners that are designed to remove imperfections from a
painted surface. They vary by the types of minerals (abrasives), mineral particle sizes and chemicals they contain, but
they provide basically the same action. Both use an abrasive to remove imperfections in the paint, and both are made
with varying degrees of aggressiveness.

How Often Should I Wax My Car?

There is no exact length of time that any wax will last. Variables such as the type, color and condition of the paint, the
amount of exposure to outdoor elements, and the quality of the wax all affect how long it will last. Generally speaking,
when the water beading and the finish appearance indicate that the wax is gone, you should re-apply the wax.

Why do I Need a Car Wash soap?

Car wash soaps are specially formulated to remove dirt, grime and soils commonly found on vehicle surfaces, while
having a minimal affect on the wax finish. Many other soaps, such as dish washing detergents, are formulated to
remove tougher soils like cooking oils and greases. These stronger soaps can attack a wax finish, reducing the overall
life of the wax.

Repainting Interior Vinyl and Plastic Trim

How do you repaint the interior vinyl and plastic trim pieces in
your Z car?

Painting the interior vinyl and plastic trim in a Z is fairly easy.
There are two sources for the dye. If you don't have a paint gun,
then find SEM vinyl dye in spray cans at a good paint store. SEM is
the only way to go, and I have never found another product that
works as well or lasts so long. It also looks completely like the
factory finish. Please do not even consider any other brand.

Use "Satin Black" for the black interiors, and "Napa Red" for the
red interiors. The "Napa Red" is a precise match for the Datsun red
interior color. They also have ZX colors, too. SEM is about $7 a
can. and I use 4 to 6 cans for an entire interior on a 240Z.

If you have a paint gun (a door jamb gun is a good choice, or an
HVLP jamb gun is even better). Dupont has vinyl dye that is
comparable to SEM. It is about $20 for a quart, which will do one
car interior.

Preparation is everything! Here's the process:

1. Remove the seats and the carpet pieces.
2. Throughly vacuum out the interior.
3. Use low-lint paper towels to clean all the vinyl and plastic
interior pieces with a water based cleaner, such as soap & water,
ammonia, Mr Clean, Pineoil, etc., and let dry.
4. Wet wipe the surfaces with lacquer thinner. Not enamel reducer
or poly thinner, just cheap lacquer thinner. Wipe and scrub and
scrub. You will notice the vinyl and plastic getting soft. Stop
before you ruin the grain pattern! The theory behind the lacquer is
that it chemically softens the vinyl/plastic. When you apply the
dye, it soaks in much better.
5. Mask off all the unpainted items. I use "Big Gulp" bottoms taped
to the gauges.
6. Now shake your paint can. If you are using the Dupont dye, it is
ready to spray, without thinning.
7. Re-wipe the surfaces quickly with a very wet paper towel SOAKED
IN THINNER, and start fogging on the dye. It is very thin. You may
end up with 5-12 coats to get good heavy coverage. Let dry, and you
are done.

Note: Do not paint the seats, it will scrape off eventually.

Dupont also has a "textured" paint to match the texture of vinyl
tops. So it happens to look like vinyl when it is dry. I use it on
the sill plates of the 240Z's.

The stuff is very durable when dry. It does not exactly match the
Datsun sill plate vinyl, but it is a lot easier than trying to
recover the sill piece with contact cement and vinyl cloth. This
paint has to be applied with a non-HVLP gun (your normal old
fashioned gun is not HVLP). It's the air pressure that makes the
spiderwebs as it comes out, which then coagulate into the vinyl
texture. This coating can then be re-coated with black semi-gloss
vinyl dye to match the panels.

Tech Tip

What does it take to put the R200 differential in a '70-71 240Z?

Because the '72 and later Z cars moved the differential rearward about 1 3/8 inches, using
the R200 in an '70 and '71 Z car requires some special consideration. BTW, this was a design
change implemented by Nissan in 1972 to reduce the halfshaft angle and thus reduce vibration
and U-joint wear.

You will need:

1. The '72-'78 U-shaped rear suspension crossmember. This has a "curve" or bend in it to
clear the larger R200 differential housing and also because you are actually moving the diff
back a little.

2. A '72-'78 driveshaft. This is about 25mm longer in length. Note: the '72-'74 driveshaft
have replaceable U-joints, nice for maintenance.

3. The R200 "moustache bar". This supports the rear of the differential. The R200 bar has a
curve in it and it is drilled for the wider mounting bolt pattern of the R200.

4. The R200 front rubber differential mount.

You can get everything off of 280Z that had an R200, i.e., a manual transmission 280Z. Your
stub axles will bolt up OK, even though the R200 is slightly wider than your old R180.

Now, you will find out that the diff strap now comes directly over the R200 front rubber
mount bolts. Since the nuts are on top, there's now not enough slack in the strap to bolt up.
The later Z cars moved the four bolts for the diff strap rearward.

So, you can remove the strap and use several turns of 3/16 inch steel cable threaded between
the front rubber mount and the diff and then wrapped around the front diff crossmember to
secure the diff. However, I recall talking to someone who used the 280Z diff strap, and
reversed the direction of the front rubber mount bolts so that the slim bolt head was on top
and nuts on the bottom. This gave him enough "slack" in the strap.

Replacing Your Rear Wheel Bearings

Replacing rear wheel bearings on your '70-'78 Z car is something
you may have not yet undertaken, as it is not part of normal
maintenance and usually only needed on very high mileage Z cars.
Although some backyard mechanics may seem intimidated by the this
project, there's no reason that you can't accomplish it with some
guidance.

First, securely support the rear of the car and remove the rear
wheels. Now you don't have to remove the rear struts off the car.
Although arm room is limited and having the car on a lift will
help, I have accomplished this just with jackstands. This saves you
some time and you don't have to re-bleed the brakes. However, if
you're a first-timer, you are probably better off removing the rear
strut, as it gives you more access space.

Remove each strut by unbolting the rear halfshafts, the brake line,
the parking brake cable and the inner lower transverse link mount
from the car. There is no need to remove the transverse link arm
from the strut, as this can be more difficult than changing rear
bearings!

After removing the strut, you will see a large 27mm nut on the back
side of the stub axle. This nut has a "staked" or "peened" top,
which means it's top lip has been bent over on two flat surfaces on
the stub axle threads. This technique securely locks the nut in
place, preventing it from loosening, but it makes removal somewhat
difficult.

To remove the peened stub axle nut, first chisel all the way around
the top of the nut, not only just where it is flattened. Try to
bend the entire top lip of the nut away from the shaft. Do not try
to remove the nut until you have done this! This prevents any
damage to the stub axle shaft threads as the nut is unscrewed. In
addition, the peening greatly increases the amount of torque needed
to loosen the nut. Don't worry about damaging the nut, you'll
replace it anyway.

You can also us a high speed cutting wheel (even a Dremel) to cut
away the top of the nut--just go slowly and be careful not to cut
the stub axle threads where the nut has been peened over.

Now, the easiest method to loosen the nut is to use an air impact
wrench. However, if you don't happen to own one, then you will have
to resort to a 1/2 inch drive breaker bar (usually along with a
"cheater bar") and some arm muscle as the nut is tightened down
with some 200 foot-pounds of torque!

To keep the wheel/tire from rotating as you loosen/tighten the stub
axle nut: Go down to your local scrap iron yard and get a 1" by 1"
rectangular (hollow) metal bar about five feet long. Should cost
you about $5. Drill two holes in one end and bolt it to two of the
four holes in the flange that surrounds the stub axle nut. Leave
room for your 27mm socket.

If the nut is stubborn you can use a torch to heat up the nut. This
expands the nut a little and makes it easier to get the nut loose.

After the nut is [finally!] removed the stub axle can be removed
from the strut housing. The stub axle is pressed into place so it
must be driven out. There are two methods: "pushing" or "pulling".
Pulling requires using a hub puller that is bolted to the flange
where the wheel is mounted using lug nuts. A hub puller looks like
a large dent puller with a sliding weight and can be rented from a
tool rental place. You then use the sliding weight to pound the
stub axle out. It takes a lot of effort, but it is the safer method
as it will not damage the stub axle threads.

Pushing is easier, because you don't need to have access to a hub
puller. Using a large brass hammer the stub axle is hammered out
from the backside of the strut. Extreme care must be used so as to
not damage the threads of the stub axle! After removing the inner
splined flange piece, reverse the 27mm nut and re-thread it back on
the first several threads to protect the shaft and use a piece of
wood or hard plastic between the hammer and the top of the shaft.
Several strong blows will force the stub axle out of the strut.

Once the stub axle is has been removed from the strut, examine the
splines. Wear here is not unusual and this can cause a "clunking"
noise during gear shifts.

One of the rear axle bearings (there are two per side), the outer
one, will come out with the stub axle. To remove this bearing
requires what is called a "clamshaft puller". Again, you can rent
one, but I recommend taking the stub axle (along with a new
bearing) down to your local automotive machine shop and have them
remove the old bearing and put the new one on.

There is a hollow tubular "spacer" piece which can then be removed
and then the inner bearing can be removed with a brass drift and
hammer, after the seal has been pried out.

The bearings cost around $15 to $20 each. Aftermarket ones are OK.
You will need a new seal as well.

Installation is the reverse sequence. Tap in the new inner bearing
and then a new oil seal. Lube the lip of the oil seal with wheel
bearing grease and force some grease into the new bearings. Re-pack
the inner portion show by an asterisk in the below figure with
grease. Don't forget about the spacer piece. Install the stub axle
and tap into place.

During re-assembly, I like to use the '82-'83 280ZX stub axle nut
(Nissan part number 43262-W1200). This is a true "lock nut" type,
so you do not have to flatten or "stake" it's sides. This will make
(dare I say it!) future disassembly easier.

When retorquing the new 27mm nut, apply some anti-seize compound to
the threads to prevent galling, and torque to the recommended value
(which involves monitoring the force required to spin the axle,
measured at the wheel stud). The torque required is somewhere
between 180 and 240 ft-lbs. However, most people just re-torque to
200 ft-lbs. For this, use a regular Craftsman torque wrench (good
to 250 ft-lbs).

Replacing Fuel Injector Hoses

Or "How to replace the hoses connecting the fuel injectors to the
fuel rail on your 280Z or 280ZX without replacing the injectors
themselves". This is at least a four hour job.

Before you begin, make sure you have two feet of 90+ psi rated fuel
hose, inside diameter 5/16". This can be very hard to find, and do
not let anyone sell you standard 50 psi rated fuel hose. Your FI
(fuel injection) system can put out more than 50 psi, so this is
not adequate. When you go looking for hose no one may know what
you're talking about. If you talk "fuel injector hose" to auto
parts stores, they may be able to help. The hose on the FI Z(X) is
metric, 7mm to be exact and costs about $12/ft (ouch!) if to have
to get it from your local Nissan dealer.

I found suitable replacement hose at a NAPA parts store, $11 for
two feet. I don't recommend using the same stainless clamps Nissan
used on the rail end of the hoses. They're $2.50 each and are hard
to re-use, as they tend to jam when tightening and cannot open any
wider to accommodate a larger hose then the original. If you buy a
larger OD hose, the factory clamps will not work! Get your clamps
with the hose and make sure they are compatible! I ended up using
twelve new generic-type hose clamps.

To begin: Release pressure in the fuel lines by disconnecting the
fuel pump while the car is idling. The connector is found under the
back cargo pad, forward and slightly to the right of center. Your
manual will show the location. The car will idle for a few seconds,
then die as fuel runs out.

Disconnect everything in your way. This will include the large hose
PCV connection to the top center of the valve cover, and misc.
vacuum lines. You will also need to disconnect your spark plug
wires and get them out of the way. Be sure to number or otherwise
identify the wires. You may find it most convenient to remove the
cap and wires entirely just to get them out of the way.

Here's a trick: To number plug wires at either end, use the plastic
snap-on tabs which are used to close bread wrappers. Write a wire
number on the tab with a fine point permanent marker and snap over
the plug wire. They can be re-used almost forever. This is real
handy when doing ignition work requiring you to disconnect wires.

You will need to disconnect two fuel lines and one cooling line on
the right front of the engine. The fuel hoses are hard to get off
because they are the same material as the FI hoses, and very stiff.
Be patient. One hose will leak gas and must be plugged with a spare
bolt when disconnected. It's sneaky and may not leak at first, but
it will eventually! The cooling line will spout water and must also
be plugged after being disconnected.

There is one bolt on the right front corner of the engine which
holds the fuel lines and coolant line in place; remove this. When
re-installing, put this bolt in before you re-attach the hoses;
when attached to the lines, the hoses tend to pull the bracket
holes out of alignment with the bolt hole and make it tough to
re-install!

You will find there is a stud on the top left corner of the
engine's front which holds the fuel and cooling lines in place. It
also holds the top of the PS belt tensioner in place. Here's the
work sequence:

1) Using a 14mm socket, loosen the nut in the front of the power
steering idler pulley. This allows the pulley to move. 2) Using the
tensioner bolt, slack the power steering belt enough to remove it
from the pulley. 3) Remove the nut from the stud, and remove the
lower left bolt which holds the tensioner to the block. Loosen the
third tensioner bolt but do not remove it; this will allow enough
slack to move the tensioner off the stud. 4) Find a second nut
which will go onto the stud; lock the two nuts together firmly and
use them to turn the stud out of the block. Now the lines are
free.

Remove the three bolts (two are small and easily visible, the third
is a large bolt which doubles as an intake manifold bolt) which
hold the fuel rail in place.

Remove the three small bolts which hold the valve body (the round
thing with a vacuum line going to it) in place in the center of the
fuel rail; you must be able to move it to get at the injector
underneath. I found that I had to remove one (the upper and easier
to reach) of the two fuel hoses attached to it, and was then able
to move it enough to work underneath it.

Now the rail should be loose enough to wiggle slightly. If not,
look around and find out what I've forgotten - or what is different
on your car.

To disconnect the FI electrical connections can be tricky. I used
a fine-point scratch awl on the very tips of the metal clips to
push them out far enough that I could get a fine point under them
and remove them by prying outward. In this process, I found it's
almost impossible to avoid breaking off a tiny plastic retaining
tab which holds the center-back of each clip in place. These
plastic pieces get old and brittle, and I don't have a solution for
this. I just pried carefully and made sure not to lose the metal
clips. Once the clips are off, the connector pulls off easily.
WARNING: these connectors are very brittle. Keep them out of your
way while prying and working, because if you push against one, it
will shatter and you'll be buying a replacement!

To get the old hoses off:

1) Loosen FI hose clamps and slide down toward injector. If you
don't have to open them up and remove them, they may work better on
re-assembly. 2) Using a very sharp knife or industrial type razor
blade, slit the hoses where they contact the fuel rail. You are NOT
going to be able to pull this fuel rail off without doing this, the
hoses are much too stiff and aggressive in their hold. Don't worry
too much about scratching the fuel rail, it's hard enough that you
would have to carve hard to damage it. 3) Peel back the hoses and
pull the fuel rail out of them. It won't go far because of things
which restrict its movement, but you can get it loose. 4) Slide the
stainless clamps off over the hose ends. 5) Using sharp diagonal
cutters, snip through the soft metal crimp rings which hold the
bottom of the hoses in place. These are softer than is apparent,
and cut fairly easily. If you keep working the cutters down further
into the rings, you can cut them in half. 6) Remove the metal rings
and using a sharp knife or razor blade, slice through the bottom
half of the hoses where they go over the fuel injector inlets.
NOTE: although the body of the injector is Bakelite, the inlets are
metal! They have two aggressive barbs to hold the hose in place.
Again, you don't have to baby them, you can keep cutting till
they're off. You would really have to hack on one before you would
scratch it enough to cause any damage. 7) Remove the hoses.

Then cut your new hose sections to length and slide them onto the
FI inlets. A few drops of WD-40 inside the hose will help to
lubricate the hose. You will have to push hard! I used the butt end
of a screwdriver to push on them until they were fully seated.

When installing the clamps, think carefully about where to point
the screws; consider what you'll have to work around if you need to
tighten them AFTER you get the fuel rail back in place!

After hoses are in place, install bottom clamps; then slide the
clamps for the hose tops over the hoses, lubricate inside-tops of
hoses with WD-40 and press the fuel rail into the hoses. Use the
clean marks on the rail for a reference on how far in to press. You
will have to work back and forth to do this - those hoses are stiff
enough that it takes some work to press the fuel rail into them.

Tighten clamps, re-install bolts, etc. etc. No particular tricks
going back together except to re-install the stud on front of the
engine and the bolt on the right front corner before re-connecting
the fuel and cooling hoses on the right front corner.

When all is secure, turn key on and let the fuel pump work; turn
engine over for a couple of seconds; let fuel pump work again;
repeat until it starts. The injectors will self-prime. Then idle
the car for a while; check for leaks. Clean up hands, etc. and take
on a short drive, then check again for leaks.

Replacing Fuel Injector Hoses

Or "How to replace the hoses connecting the fuel injectors to the
fuel rail on your 280Z or 280ZX without replacing the injectors
themselves". This is at least a four hour job.

Before you begin, make sure you have two feet of 90+ psi rated fuel
hose, inside diameter 5/16". This can be very hard to find, and do
not let anyone sell you standard 50 psi rated fuel hose. Your FI
(fuel injection) system can put out more than 50 psi, so this is
not adequate. When you go looking for hose no one may know what
you're talking about. If you talk "fuel injector hose" to auto
parts stores, they may be able to help. The hose on the FI Z(X) is
metric, 7mm to be exact and costs about $12/ft (ouch!) if to have
to get it from your local Nissan dealer.

I found suitable replacement hose at a NAPA parts store, $11 for
two feet. I don't recommend using the same stainless clamps Nissan
used on the rail end of the hoses. They're $2.50 each and are hard
to re-use, as they tend to jam when tightening and cannot open any
wider to accommodate a larger hose then the original. If you buy a
larger OD hose, the factory clamps will not work! Get your clamps
with the hose and make sure they are compatible! I ended up using
twelve new generic-type hose clamps.

To begin: Release pressure in the fuel lines by disconnecting the
fuel pump while the car is idling. The connector is found under the
back cargo pad, forward and slightly to the right of center. Your
manual will show the location. The car will idle for a few seconds,
then die as fuel runs out.

Disconnect everything in your way. This will include the large hose
PCV connection to the top center of the valve cover, and misc.
vacuum lines. You will also need to disconnect your spark plug
wires and get them out of the way. Be sure to number or otherwise
identify the wires. You may find it most convenient to remove the
cap and wires entirely just to get them out of the way.

Here's a trick: To number plug wires at either end, use the plastic
snap-on tabs which are used to close bread wrappers. Write a wire
number on the tab with a fine point permanent marker and snap over
the plug wire. They can be re-used almost forever. This is real
handy when doing ignition work requiring you to disconnect wires.

You will need to disconnect two fuel lines and one cooling line on
the right front of the engine. The fuel hoses are hard to get off
because they are the same material as the FI hoses, and very stiff.
Be patient. One hose will leak gas and must be plugged with a spare
bolt when disconnected. It's sneaky and may not leak at first, but
it will eventually! The cooling line will spout water and must also
be plugged after being disconnected.

There is one bolt on the right front corner of the engine which
holds the fuel lines and coolant line in place; remove this. When
re-installing, put this bolt in before you re-attach the hoses;
when attached to the lines, the hoses tend to pull the bracket
holes out of alignment with the bolt hole and make it tough to
re-install!

You will find there is a stud on the top left corner of the
engine's front which holds the fuel and cooling lines in place. It
also holds the top of the PS belt tensioner in place. Here's the
work sequence:

1) Using a 14mm socket, loosen the nut in the front of the power
steering idler pulley. This allows the pulley to move. 2) Using the
tensioner bolt, slack the power steering belt enough to remove it
from the pulley. 3) Remove the nut from the stud, and remove the
lower left bolt which holds the tensioner to the block. Loosen the
third tensioner bolt but do not remove it; this will allow enough
slack to move the tensioner off the stud. 4) Find a second nut
which will go onto the stud; lock the two nuts together firmly and
use them to turn the stud out of the block. Now the lines are
free.

Remove the three bolts (two are small and easily visible, the third
is a large bolt which doubles as an intake manifold bolt) which
hold the fuel rail in place.

Remove the three small bolts which hold the valve body (the round
thing with a vacuum line going to it) in place in the center of the
fuel rail; you must be able to move it to get at the injector
underneath. I found that I had to remove one (the upper and easier
to reach) of the two fuel hoses attached to it, and was then able
to move it enough to work underneath it.

Now the rail should be loose enough to wiggle slightly. If not,
look around and find out what I've forgotten - or what is different
on your car.

To disconnect the FI electrical connections can be tricky. I used
a fine-point scratch awl on the very tips of the metal clips to
push them out far enough that I could get a fine point under them
and remove them by prying outward. In this process, I found it's
almost impossible to avoid breaking off a tiny plastic retaining
tab which holds the center-back of each clip in place. These
plastic pieces get old and brittle, and I don't have a solution for
this. I just pried carefully and made sure not to lose the metal
clips. Once the clips are off, the connector pulls off easily.
WARNING: these connectors are very brittle. Keep them out of your
way while prying and working, because if you push against one, it
will shatter and you'll be buying a replacement!

To get the old hoses off:

1) Loosen FI hose clamps and slide down toward injector. If you
don't have to open them up and remove them, they may work better on
re-assembly. 2) Using a very sharp knife or industrial type razor
blade, slit the hoses where they contact the fuel rail. You are NOT
going to be able to pull this fuel rail off without doing this, the
hoses are much too stiff and aggressive in their hold. Don't worry
too much about scratching the fuel rail, it's hard enough that you
would have to carve hard to damage it. 3) Peel back the hoses and
pull the fuel rail out of them. It won't go far because of things
which restrict its movement, but you can get it loose. 4) Slide the
stainless clamps off over the hose ends. 5) Using sharp diagonal
cutters, snip through the soft metal crimp rings which hold the
bottom of the hoses in place. These are softer than is apparent,
and cut fairly easily. If you keep working the cutters down further
into the rings, you can cut them in half. 6) Remove the metal rings
and using a sharp knife or razor blade, slice through the bottom
half of the hoses where they go over the fuel injector inlets.
NOTE: although the body of the injector is Bakelite, the inlets are
metal! They have two aggressive barbs to hold the hose in place.
Again, you don't have to baby them, you can keep cutting till
they're off. You would really have to hack on one before you would
scratch it enough to cause any damage. 7) Remove the hoses.

Then cut your new hose sections to length and slide them onto the
FI inlets. A few drops of WD-40 inside the hose will help to
lubricate the hose. You will have to push hard! I used the butt end
of a screwdriver to push on them until they were fully seated.

When installing the clamps, think carefully about where to point
the screws; consider what you'll have to work around if you need to
tighten them AFTER you get the fuel rail back in place!

After hoses are in place, install bottom clamps; then slide the
clamps for the hose tops over the hoses, lubricate inside-tops of
hoses with WD-40 and press the fuel rail into the hoses. Use the
clean marks on the rail for a reference on how far in to press. You
will have to work back and forth to do this - those hoses are stiff
enough that it takes some work to press the fuel rail into them.

Tighten clamps, re-install bolts, etc. etc. No particular tricks
going back together except to re-install the stud on front of the
engine and the bolt on the right front corner before re-connecting
the fuel and cooling hoses on the right front corner.

When all is secure, turn key on and let the fuel pump work; turn
engine over for a couple of seconds; let fuel pump work again;
repeat until it starts. The injectors will self-prime. Then idle
the car for a while; check for leaks. Clean up hands, etc. and take
on a short drive, then check again for leaks.

Refinishing 240Z steering wheels

I have a couple of questions about the original steering wheel in
my 240Z. Is it real wood or a good fake? Also, mine looks dry and
faded, is there a way to make it look new again?

First of all the steering wheel is made of PLASTIC not wood. I did
not figure this one out until I started sanding! The easiest way to
make it look like new or better is to do the following:

1. Remove the steering wheel. Gently pry up the horn pad and remove
the 22mm nut. The wheel then can be nudged off. This will also give
you access to clean out with WD-40 the little turn signal return
springs/levers that may be gummed up and making you do the old
manual return on your turn signal lever.

2. Using a medium to fine grit sponge sand paper that you can get
in any hardware store, gently sand off the 20+ years of built up
dirt off the wheel. Be careful not to sand off the wood grain on
the plastic! Clean up using rubbing alcohol.

3. Sand the metal spokes with fine grit wet sandpaper (the
black/grey stuff) to remove any corrosion or rust.

4. Using masking tape, tape newspaper around the wheel part being
very sure to cover all the plastic/wood part of the wheel.

5. Hang the wheel from a tree limb outside with a piece of coat
hanger or cord and put three to four coats of semi-flat black paint
on the spokes. Allow each coat to dry a couple of hours and use
several light coats multiple times instead of one thick coat to get
a professional look.

6. After the spokes are dry (overnight is best), tape a covering of
newspaper over the spokes.

7. Here is the tricky part. Purchase at the hardware store or
Wal-Mart a furniture scratch pen. These look like a big brown magic
marker. I like the dark walnut color. Use the scratch pen that
matches the grain pattern and color of the steering wheel. If you
get too much on one spot you can use the pen to smooth out and
blend the color. Add a few darker lines in the grain pattern on the
plastic to make it look more like wood.

8. After the ink is dry, use a thick UV Protective Spar Varnish
applied with a loaded 2" paintbrush. The first coat is critical,
apply gently and don't be afraid to put it on heavy. Try not to dab
around too much as the scratch marker ink can come off. The ink
will mix with the varnish a little bit and add to the wood tones.

9. Add 2-4 more coats of the varnish, sanding with very fine paper
(300 to 400 grit) between coats. Touch up any spots that you sand
down too much with the scratch pen before applying the last coat.

10. Re-install the steering wheel.

The finished product will look better than original without looking
non-OEM. The UV protectant varnish will keep your wheel looking
good for the next 20+ years. The varnish will last longer on the
plastic than it would have lasted on real wood. The end result
looks like hand rubbed walnut that would have cost two to three
hundred bucks to purchase and then not look original.

If you have an artistic flair and want to experiment with different
shades of the scratch repair pens you could get some pretty exotic
wood looking combinations on the finished product.

Preventing your Z from being stolen

Having known a couple of car/stereo thieves, I can tell you that no
matter what you do to your car, it is not safe. The people I've
known have stolen cars (usually just the electronics though) with
or without alarms. They've chalked up some real nice cars too. More
than a couple of Z's, a Jag, a Lotus Esprit, and a host (100+) of
other cars. They claim that about half had alarms also. Trust me,
the people who are looking to steal your car probably know more
about the alarm system in your car than the people who put it in
(one "friend" actually made a living installing them). I'm not
saying that alarms are useless, but that if a thief wants your car
or its contents, he will get them. The alarms today have about the
same protection as the actual door lock. A good thief will disarm
your car in the same amount of time it takes to pick the lock. You
should figure that an alarm will only give you a couple of extra
seconds.

I know the last statement from experience. In my case, a couple of
seconds wasn't enough. I lost more than $400 worth of car audio and
CD's. Only reason they didn't just take the car was because it was
a Fiero. If it was a nice car, then it would have been gone too. I
didn't even bother to take the alarm out of the Fiero and put it in
my Z. I figured it didn't help the first time.

Here are my tips for keeping your car (many of these were told to
me by my car stealing friends):

1. Park in a well lighted, well populated area. I know that this is
old advice, but it is overlooked and it is the best way to deter a
thief!

2. Use valet parking. Since cars/drivers are frequently going
through the valet area, thieves tend to shy away from this area.
Besides, the valet drivers know who shouldn't be there. Also, some
places actually guarantee your car's safety.

3. If it is available, park your car in secured parking.
Considering a new Z cost a min of $25K, an extra couple hundred a
year in rent is worth it. Or take the time to clean out your garage
so your Z will fit.

4. If you buy car audio stuff, make sure you can take at least part
of the stuff out (a detachable face).

5. Don't leave your radar detector (or mount) sticking to the
window. Actually, don't use the stick on stuff because it leaves
marks on the glass they can see.

6. Don't leave CD's sitting in the seat (I know this from
experience).

7. Make your car looks like any other Z. Which would you rather rip
off, the totally stock Z, or the one with the $250 radar detector,
Alpine stereo, and obvious mods? I can guarantee you that if you
have a Turbo Z, you'll need some engine work--they're probably
trash your engine. Of course, the stock one has a good chance of
being picked out of the mall parking lot, but remember, these
people are taking a risk, they want all they can get for the risk
they're taking. So, they'll take the best out of the pick.

8. Don't leave your car in a shop's lot overnight. My friends used
to shoot the guard dogs with a pellet gun and get in there all
night. They would go home in the morning with about 30 stereos. Not
to mention whatever the owners left in their car.

Don't forget, the shop has your keys, with the license plate # on
them. The thieve will break a window, look on the wall, grab
everyone's keys, and they don't have to worry about picking locks!

Don't think for a minute that the dealerships chain link and barbed
wire will keep a thief out. And a security dog is useless. Take
your car home, or have them call you when they're ready to work on
it, so you can bring it to them.

9. Big speakers make for big targets. Be content with the stock
sizes and spend the extra money on speed.

10. Spend the extra money to have your car insured for this event.
If they don't outright steal the car, then they will tear it apart
getting everything they think they can sell.

11. If you do buy the alarm, have the wiring spliced so that you
will be able to run parallel wires throughout the car. This way,
when they snip what they think is the alarm wiring, you will have
some redundancy.

12. At night, if you think you hear someone messing with your car,
then it's too late. One of my neighbors had his car stolen while he
and his wife were in the kitchen, only one wall away from his car.

PAY ATTENTION! If you think you hear your neighbor's dog barking at
2am in the morning, then there might just be a good reason for it.

13. If your car is stolen from your home, I can almost guarantee
you that the people who did it have gone through the neighborhood
a couple of times. Be nosey. If you see strange people driving down
the street, then make sure they know you saw them. There's a good
chance that this simple action saved someone on your street the
anguish of losing their car.

My final point is, your car will never be safe, no matter what you
do. Appreciate it while you've got it. In my opinion, it's the best
reason to lease your cars. You don't get attached.

Suspension 101
Components of Suspension & What They Do

Introduction

Handling of a vehicle is determined by many variables. Some of
these are tires, center of mass (a.k.a. center of gravity), chassis
torsional stiffness, suspension geometry, suspension components
(springs, shocks, anti-roll bars), etc.

There are many things that most people do not wish to change due to
various reasons. For example, most people do not want to strip the
interior of the car to lower the center of mass. It is
understandable as it would make a very impractical street car.
Installing roll cage is not a really good idea for a street car,
either. Changing the suspension geometry is not recommended without
thorough understanding of the vehicle dynamics. Changing suspension
components is the easiest way to alter the handling characteristics
of the vehicle.

Tires

Tires are black rubber things that provides the only contact with
the road surface. Friction between tires and the road surface
creates acceleration, braking (deceleration), and cornering. Most
of you learned in high school physics that:

Ff = Cf * Fn

where Ff is the friction, Cf is the coefficient of friction, and Fn
is the normal force. Well, ladies and gentlemen, I got news for
you. This equation only applies to very special cases where both
surfaces are very hard and have reasonably smooth finish. This
equation certainly does not apply for tires.

Tire's frictional property can not be expressed as an equation
really well. If I use the above equation, Cf will decrease with
increase in Fn. As normal force increases, coefficient of friction
decreases. As a results, friction force does not increase as much
as increase in normal force. An important result of this, is that
lighter cars will turn sharper corners than heavy cars, all else
being equal.

Weight Transfer

Weight transfer is a shifting of loading on tires due to
acceleration. Increasing speed, braking, and cornering cause weight
transfer. For transverse acceleration, weight transfer can be
expressed as:

dW = (m * h * a) / t

where dW is the resulting weight transfer due to acceleration a (in
m/s^2 for metric unit and G in U.S. unit when lb. Used for mass),
m is the mass of the vehicle (kg for metric unit and lb. for U.S.
unit), h is the height of center of mass, and t is the track width.
For longitudinal weight transfer, use wheel base instead of t.

This equation calculates the total weight transfer but does not
calculate how much weight is transferred by front or rear wheels.
It required more complicated equation and a lot more details and
assumptions to calculate the weight transfer by each wheel, and I
am not about to get into that.

Just remember that, if you make on end of the car stiffer, there
will be more weight transfer at that end and lose some traction
capability due to increase loading on that end.

Springs

Springs are energy storing device. They store energy by deflection.
Most springs are constant rate springs, i.e., amount of the force
that is stored is proportional to the deflection of the spring. It
is usually expressed as:

F = k * X

Where F is the force (in lb., at least in the U.S.), k is the
spring constant (or spring rate) in force per deflection
(lb./inch), X is the deflection (in).

There are also progressive springs. Progressive spring's spring
constant (k) increases with deflection.

OK, enough about what springs are. We can now talk what springs do
in a car. Springs absorb bumps, limits the motion of the vehicle
due to acceleration, braking, cornering, etc.

Shocks

Shock absorbers dampen the motion of suspension. Shock absorbers do
not absorb impacts; springs do. Shock absorbers are dampers.

Shock absorbers also control the transient motion of the vehicle.
Shock absorbers control HOW the car nose dive when brake is
applied. Springs control HOW MUCH car nose dives. Shock absorber
controls HOW the car goes into roll when the steering is applied.
Springs and anti-roll bar control HOW MUCH car rolls.

There are some adjustable shocks available. Adjusting the extension
of the shock is called "rebound," and adjusting other direction is
"bump."

Anti-Roll Bars

Anti-roll bars are also known as roll bars, sway bars, anti-sway
bars, etc. Anti-roll bars connect right and left wheel. They resist
roll by twisting themselves, acting as torsion springs.

Tuning Springs, Shocks, & Anti-Roll Bars

You have to understand few terms before I can explain how to tune
suspension.

Understeer ("Push" for circle track people): Handling
characteristic that, when car is turning on the constant radius
circle, front end of the car pushes to the outside of the circle
with increasing speed. Turning radius of the car increases with
increasing speed, or more steering is necessary with increasing
speed. It is caused by front end of the car having less traction
than rear end.

Oversteer ("Loose"): Handling characteristic that, when car is
turning on the constant radius circle, rear end of the car pushes
to the outside of the circle with increasing speed. Turning radius
of the car decreases with increasing speed, or less steering is
necessary with increasing speed. It is caused by front end of the
car having more traction by rear end.

Neutral: Ideal condition that is rarely achieved. Car turns on the
constant radius circle with constant steering angle with increasing
speed. As strange as it seems, some racing cars can do this, until
you lose traction and get into severe oversteer.

Entry: Imagine that you are approaching a long sweeper. Turn-in is
when you turn the steering and wait for the car to "settle" to
steady state roll angle.

Steady State: Your car is finished turning in. You are giving the
car constant steering angle and throttle angle.

Corner Exit: You are beginning to get on the gas pedal and unwind
steering.

Symptoms & Solutions

Entry Understeer: Increase the rebound of rear shocks. Decrease the
bump of front shocks. Increase the rear brake bias. Brake earlier.

Entry Oversteer: Decrease the rebound of rear shocks. Increase the
bump of front shocks. Decrease the rear brake bias.

Steady State Understeer: Stiffen rear spring and/or anti-roll bar.
Soften the front springs and/or anti-roll bar.

Steady State Oversteer: Stiffen front spring and/or anti-roll bar.
Soften the rear springs and/or anti-roll bar.

Exit Understeer: Increase rebound of front shocks. Decrease bump of
rear shocks. Stiffen rear springs/anti-roll bar. Soften front
springs/anti-roll bar.

Exit Oversteer: Decrease rebound of front shocks. Increase bump of
rear shocks. Soften rear springs/anti-roll bar. Stiffen front
springs/anti-roll bar.

Car is slow to respond to driver's input: Stiffen the car by
springs, anti-rollbars, and shocks. Increase tire inflation
pressure.

Car hops over the bump: Soften the car. Decrease tire inflation
pressure.

Conclusion

As you can see, changing one thing can alter the all three stages
of the handling. You will have to make a compromise that best suits
to your requirement. There are also more variables such as ride
height of the vehicle, wheel alignment, tires, driving style, gross
weight, etc., that can alter the handling of a vehicle.

Tech Tip - Tire Talk

What do the numbers on the sides of my tires mean?

Typically, you will see something like 195/60HR14. The 195 is the
overall width of the tire in millimeters, the tread is usually
narrower. Now much narrower depends on the tire's design. Each tire
make and size is measured on a reference rim of the manufacturer's
choosing. If they measure P275/60R15 on a 7x15 rim and you try
mounting it on an 8x15 rim, your tire will have different
dimensions than they claim.

The 60 is the "aspect ratio". This indicates the height of the
sidewall of the tire relative to the overall width. Our example
tire has a sidewall height of 0.60 * 195 = 117mm. If the aspect
ratio is omitted, it is probably 80, but may be 78.

The 14 is the wheel diameter in inches. The R stands for radial,
and the H is a speed rating indicating the highest speed at which
the tire, when properly inflated and carrying an appropriate load
may safely operate. There are almost as many speed ratings as there
are letters in the alphabet, and they basically go in 10 km/h
increments. The most common ones are:

S: up to 180 km/h (112 mph)
T: up to 190 km/h (118 mph)
H: up to 210 km/h (130 mph)
V: up to 240 km/h (150 mph)
Z: above 240 km/h (150 mph)

Recent changes to the method for specifying tire sizes move the
speed rating to a different part of the designation. You may
therefore find designations like 195/60R14 88H. The 88 indicates
the per-tire load associated with the speed rating. Exceeding this
load in continuous operation at the rated speed is considered
dangerous practice. What follows is a table showing a number of
"load indexes" and corresponding maximum per-tire loads:

load index max load (kg)
50 190
51 195
88 560
89 580

Note that the usual mass versus weight confusion occurs in this
table.

In some cases, the letters P or LT may be found in front of a tire
size. The LT designation indicates "light truck", and the P
designation indicates "passenger car". If no letter is given, then
the application of the tire is passenger car usage. These letters
only appear in the US market. The LT designation is principally of
interest to owners of light trucks and other utility vehicles. For
the owner of a passenger vehicle, there is no meaningful difference
between a tire with a P designation and one with no designation at
all.

There is an additional set of ratings on tires for temperature,
traction, and treadwear. Temperature and traction are graded A, B,
and C (with A the best and C the worst). Treadwear is a numeric
rating. These values are of limited value, as they are assigned
somewhat arbitrarily by tire manufacturers and are thus not useful
in comparing different brands of tires.

Additionally, the designation M+S (mud and snow) means that the
tire is at least somewhat applicable to use in mud and snow, and
should be taken as a indication that at least some thought went
into designing a tire which could be used in winter conditions. Not
all M+S tires are much good in winter, though. Some might work
during winter in San Francisco but not in Toronto, for example.
Tires with an M+S designation may have their speed rating reduced
by 20 km/h (about 12mph).

Tech Tip
Finding vacuum Leaks

Vacuum leaks are air leaks. Air leaks lower the intake manifold
vacuum reading and lean out the mixture. Depending on the size of
the leak and the type of engine control system, the leak may tell
(via the oxygen sensor) the vehicle's computer to richen the
mixture. So a long term rich compensation could point to an air
leak.

The size and location of the air leak make a major impact on
diagnosis. For example, an air leak on one intake runner or at one
injector should make that cylinder look weak on a "power balance
test". This test is done by shorting out each spark plug so that a
particular cylinder is disabled and noting the rpm reduction. Under
normal conditions the rpm reduction is about the same for each
cylinder.

When the air leak is at a somewhat centralized location such as in
or under a throttle body, throttle housing, or carb base, it
affects several cylinders at once and may cause an erratic power
balance test. When you have trouble repeating the cylinder balance
test results, check for a centralized air leak first.

Technicians usally pinpoint air leaks by spraying a fluid at a spot
and listening for a change in engine speed. Usually, the engine
stumbl