1988 PONTIAC FIERO tire pressure reset

brake light fog light ESP inoperative window clutch service interval reset

Page 138 of 1825

PONTIAC FIERO 1988 Service Repair Manual
STEERING, SUSPENSION, TIRES AND WHEELS DIAGNOSIS 3.13
in doubt about the condition, compare with a
shock known to be good.
Noisy
For struts, follow Steps 1 through 3.
1. Check all mou

STEERING, SUSPENSION, TIRES AND WHEELS DIAGNOSIS 3.13
in doubt about the condition, compare with a
shock known to be good.
Noisy
For struts, follow Steps 1 through 3.
1. Check all mountings for proper torque. A loose
mounting will cause a noise.
2. If all mountings are intact, bounce the car as in
Step
4 (weak) to isolate the suspected unit.
3. If practical, ride with the owner to be sure you
understand the complaint, before proceeding to
next step.
4. If one of the rear shocks is noisy, the rear axle
should be supported at least enough to unload the
shock mounts. Disconnect the lower mounting of
the suspected shock. Quickly push the shock all
the way in, then all the way out.
A hissing noise
is normal.
5. Other objectionable noises may be detected by
stroking. Any sound other
than hissing is
abnormal; replace the shock.
Leaks
1. Fully extend the strut/shocks (wheels
unsupported) to expose the seal cover area for
inspection.
2. Look for
signs of leaks in the seal cover area.
3. A slight trace of fluid is NOT cause for
replacement; the seal permits some seepage to
lubricate the piston rod. There is a built in fluid
reserve to allow for seepage.
4. A leaking strut dampener/shock can easily be
found because there will be fluid around the seal
cover and an excessive amount of fluid on the
strut
dampener/shock. A leaking strut
dampener/shock must be replaced.
BENCH CHECKS
Strut Dampeners and Regular Shock Absorbers
(Standard and Firm Ride)
Regular strut dampenerdrear shocks use a
gas-filled cell in the fluid reservoir. Aeration or
foaming of the fluid is eliminated, as the gas and the
fluid cannot mix.
Proceed with the actual bench check as follows:
1. Clamp the strut dampener/shock UPSIDE
DOWN in the vise. Do not clamp on the reservoir
tube or the mounting threads. If a lag is noticed
when it is stroked, it means the gas-filled cell has
ruptured and replacement is necessary.
2. Pump strut dampener/shock by hand at various
rates of speed and note the resistance.
3. Rebound resistance normally is stronger than
compression resistance by about 2 to 1. However,
the resistance should be smooth and constant for
each stroking rate.
4. Compare with a strut dampener/ shock known to
be good.
5. It is normal to hear a hissing noise. The following
symptoms are abnormal and are reason for
replacement. A.
A skip or lag at reversal near mid-stroke.
B. A seize (except at either extreme end of
travel).
C. A noise (such as a grunt or squeal) after
completing one full stroke in both
directions.
D. A clicking noise at fast reversal.
E. Fluid leakage.
TIRE DIAGNOSIS
Irregular and Premature Wear
Figs. 14 and 15
Irregular and premature tire wear has many
causes. Some of them are: incorrect inflation pressures,
lack of regular rotation, driving habits, or improper
wheel alignment. If wheel alignment is reset due to a
tire wear condition, always reset toe as close to zero
degrees as the specification allows.
1. WEAR INDICATORS I
Fig. 14 Tire Wear Indicator
If the following conditions are noted, rotate the
tires:
@ Front tire wear is different from rear.
Uneven wear exists across the tread of any tire.
e Left and right front tire wear is unequal.
Left and right rear tire wear is unequal.
Check wheel alignment if the following
conditions are noted:
e Left and right front tire wear is unequal.
Wear is uneven across the tread of any front tire.
e Front tire treads have a scuffed appearance with
"feather" edges on one side of the tread ribs or
blocks.
Wear Indicators
Fig. 16
The original equipment tires have built-in tread
wear indicators to show when the tires should be
replaced. These indicators will appear as 12.7 mm
(1/2") wide bands when the tire tread depth becomes
1.6 mm (2/32"). When the indicators appear in 2 or
more grooves at
3 locations, replace the tire.

Page 290 of 1825

PONTIAC FIERO 1988 Service Repair Manual
REAR AXLE 48-1 7
approached. No further tightening should be
attempted until the pre-load has been checked.
7. Check pre-load by using an inch pound torque
wrench.
NOTICE: After pre-

REAR AXLE 48-1 7
approached. No further tightening should be
attempted until the pre-load has been checked.
7. Check pre-load by using an inch pound torque
wrench.
NOTICE: After pre-load has been checked, final
tightening should be done very carefully. For
example, if when checking, pre-load was found to
be 0.6
N-m (5 lbs. in.), any additional tightening
of the pinion nut can add many additional pound
inch of torque. Therefore, the pinion nut should be
further tightened only a little at a time and the
pre-load should be checked after each slight
amount of tightening. Exceeding pre-load
specifications will compress the collapsible spacer
too far and require the installation of a new
collapsible spacer.
While observing the preceeding note, carefully set
pre-load at 2.7 to 3.6
N-m (24 to 32 1b.in.) on new
bearings or 1.0 to 1.4
N m (8 to 12 1b.in.) on used
bearings.
8. Rotate pinion several times to assure that
bearings have been seated. Check pre-load again.
If pre-load has been reduced by rotating pinion,
reset pre-load to specifications.
Rear Axle Backlash Adjustment
1. Install rear axle case into carrier, using shims as
determined by the side bearing pre-load
adjustment.
2. Rotate rear axle case several times to seat
bearings, then mount dial indicator. Use a small
button on the indicator stem so that contact can
be made near heel end of tooth. Set dial indicator
so that stem is in line as nearly as possible with
gear rotation perpendicular to tooth angle for
accurate backlash reading.
3. Check backlash at three or four points around
ring gear. Lash must not vary over
.05mm (.002")
around ring gear. Pinion must be held stationary
when checking backlash. If variation is over
.05mm (.002") check for burrs, uneven bolting
conditions or distorted case flange and make
corrections as necessary.
4. Backlash at the point of minimum lash should be
between .13 and
.23mm (.005" and ,009") for all
new gears.
5. If backlash is not within specifications, correct by
increasing thickness of one shim and decreasing
thickness of other shim the same amount. This
will maintain correct rear axle side bearing
pre-load.
For each
.03mm (.001") change in backlash
desired, transfer
.05mm (.002") in shim
thickness. To decrease backlash
.03mm (.00lU),
decrease thickness of right shim .05mm (.002")
and increase thickness of left shim .05mm (.
002 "). To increase backlash .05mm (.002 ")
increase thickness of right shim .10mm (.004")
and decrease thickness of left shim .10mm (.
004"). 6.
When backlash is correctly adjusted, remove both
bearing caps and both shim packs.
Keep packs in their respective position, right or
left side.
Select a shim
.10mm (.004") thicker than the one
removed from the left side, then insert left side
shim pack between the spacer and the left bearing
race. Loosely install bearing cap.
7. Select a shim
.10mm (.004") thicker than the one
removed from right side and insert between the
spacer and the right bearing race. It will be
necessary to drive the right shim into position
(Fig. 614).
8. Torque to 75 Nem (55 1b.ft.).
9. Recheck backlash
and correct if necessary.
10. Install axles (See Rear Axle Installation).
11.
Use sealant 1052366 or cover gasket
only.
Install cover and torque cover bolts to 27
N-m (20 1b.ft.).
12. Fill rear axle to proper level with the specified
lubricant. Refer to specifications.
LIMITED SLIP REAR AXLE (GONE TYPE)
The cone-type limited-slip differential has several
definite operating characteristics. An understanding of
these characteristics is necessary as an aid to diagnosis.
The clutch energizing force comes from the
thrust side of the gears. Consequently, a free spinning
wheel may not have enough resistance to drive torque
to apply the clutch cones. If this occurs, apply the
parking brake a few notches which will provide enough
resistance to energize the clutch cones.
Energizing the clutch cones is independent of
acceleration; therefore, a very slow application of the
throttle on starting is recommended to provide
maximum traction by preventing "break away" of
either rear wheel.
Improper operation is generally indicated by cone
slippage or grabbing. Sometimes this produces a
chatter or whirring sound. However, these sounds do
not always indicate failure as they could be produced
from a lack of proper lubrication. For example, under
certain conditions where one wheel is on
a very slippery
surface and the other on dry pavement, wheel spin can
occur if over acceleration is attempted. Continued
spinning may cause audible noise, such as a whirring
sound, due to the cones lacking sufficient lubricant.
This does not necessarily indicate failure of the unit.
During regular operation (straight ahead driving)
when both wheels rotate at equal speeds, there is an
approximately equal driving force delivered to each
wheel. When cornering, the inside wheel delivers extra
driving force causing slippage in both clutch cones.
Consequently, the operational life of the limited slip
unit is dependent upon equal rotation of both wheels
during straight ahead operation. If wheel rotation for
both rear wheels is not equal during straight ahead
operation, the limited-slip unit will constantly be
functioning as if the vehicle were cornering. This will
impose constant slippage on the clutch cones and will
eventually lead to abnormal wear on the clutch cones.
Therefore, it is important that there be no excessive
differences in the rear wheel tire sizes, air pressures, or

Page 1422 of 1825

PONTIAC FIERO 1988 Service Repair Manual
INSTRUMENT PANEL: DlGlTAL CLUSTER a
SYSTEM DIAGNOSIS
0 Do the tests listed for your symptom in the
Symptom Table below, or when
direded by
the System Check.
0 Tests follow the Symptom Ta

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