1988 PONTIAC FIERO Service Repair Manual

4A-8 PROPELLER SHAFT
1. REFERENCE MARKS
J10011-4A-F
Figure 4A-1 1 Reference Marks on Propeller Shaft
1 2. REAR U-JOINT
1. HOSE CLAMP HEADS 2. CRAYON MARK 180" FROM CRAYON MARK
Figure 4A-12 Balance Hose Clamps in Place
1. Raise vehicle on hoist. Mark relationship of shaft
to rear axle pinion companion flange and
disconnect the rear universal joint by removing
strap bolts. If bearing caps are loose, tape
together to prevent dropping and loss of bearing
rollers.
2. Withdraw propeller shaft slip yoke from
transmission by moving it rearward and passing
it under the axle carrier.
NOTICE: Do not allow propeller shaft to drop or
allow universal joints to bend to an extreme angle,
since this may fracture the nylon injected joint
internally. Support propeller shaft during removal.
Installation
Figure 4A-13 Rotating Balance Hose Clamps
7. Rotate two of the hose clamps equally away from
each other toward the top (one on each side of the
position) in small increments until the best
balance is achieved.
In some cases it may be necessary to use one
clamp or possibly three clamps in order to obtain
a good balance.
Replace the propeller shaft if three hose clamps
do not correct problem.
8. Install wheels and road test vehicle for final check
of balance.
Vibration felt in the vehicle on the hoist may not
show up during a road test.
PROPELLER SHAFT
Removal NOTICE:
The
propeller shaft must be supported
carefully during handling to avoid jamming or
bending any of the parts.
1. Inspect outer diameter of splined yoke to ensure
it is not burred since this may cause damage to
the transmission extension housing seal and/or
bushing. Inspect splines of slip yoke for damage
or wear.
Apply lubricant to splined propeller shaft yoke and
slide yokelpropeller shaft assembly onto transmis-
sion output shaft.
Do not drive propeller shaft
in place with hammer.
Check for burrs on
transmission output shaft spline, twisted slip yoke splines, or possibly the wrong slip
yoke. Make sure that the splines agree in
number and fit. To prevent trunnion seal
NOTICE: Do not pound on original propeller
shaft yoke ears as nylon injected joints may
fracture.

PROPELLER SHAFT 4A-9
damage, do not place any tool betvveen pro-
peller shaft yoke and the universal joint
spider.
When making the rear propeller shaft connection,
be sure to align marks made on the pinion flange and
propeller shaft prior to removal.
DROP TWIN POST HOIST JUST ENOUGH TO ALLOW
THE
"V" OF THE HOIST TO CLEAR THE AXLE
THUS PLACING THE WEIGHT OF THE VEHICLE
ON THE STANDS. THE SYSTEM
WILL THEN
BE RELEASED AND FREE TO RESPOND TO
PROPELLER.
Figure 4A-14 Pick-Up Unit at Differential Pinion Nose
3. Align rear universal joint to rear axle pinion
companion flange, making sure bearings are
properly seated.
4. Install rear universal joint straps and fasteners
and torque to specifications.
UNIT REPAIR
UNIVERSAL JOINTS
NOTICE: Mark slip joint and propeller shaft to
ensure correct reassembly.
Nylon Injected Ring Type
Disassembly
Figures 4A-16,4A-18 and 4A-19
NOTICE: Never clamp propeller shaft tubing in
a vise, as the tube may be dented. Always clamp
on one of the yokes and support the shaft
horizontally. Avoid damaging the slip yoke sealing
surface. Nicks may damage the bushing or cut the
transmission extension housing seal.
1. Support the propeller shaft in a horizontal
position on line with the base plate of a press.
Place the universal joint so that the lower ear of
the shaft yoke is supported on a
1 1/8" socket.
Place Tool
J-9522-3 on the open horizontal
bearing cap and press the lower bearing cap out
of the yoke ear. This will shear the nylon injected
retaining ring on the lower bearing cap. If the
bearing cap is not completely removed, lift Tool
5-9522-3 and insert Spacer J-9522-5 between the
seal and bearing cap being removed, as shown.
Complete the removal of the bearing cup by
pressing it out of the yoke.
2. Rotate
the propeller shaft, shear the opposite
nylon injected retaining ring and press the
bearing cap out of the yoke.
3. Disengage cross from yoke and remove.
4. If the front universal joint is being replaced,
remove the pair of bearing caps from the slip yoke
in the same manner.
Assembly
Figures 4A-20 thru 4A-22
NOTICE: Production universal joints of this type
cannot be reassembled. There are no snap ring
bearing retainer grooves in production nylon
injected ring retained bearing caps.
When reassembling a propeller shaft, always
install a complete universal joint service kit. This kit
includes one
(1) pregreased cross assembly, four (4)
service bearing cap assemblies with seals, needle
rollers, washers, grease and four
(4) snap rings. Make
sure the seals are in place on the service bearing caps
to hold the needle rollers in place during handling.
Nylon injected types are replaced by external snap ring
types, unless specified otherwise in the service parts
manual.
1. Remove all of the remains of the nylon injected
bearing cap retainers from the grooves in the
yokes. The sheared nylon may prevent the
bearing caps from being pressed into place, and
thus prevent the bearing retainers from being
properly seated.
2. Install one (1) bearing cup part way into one side
of the yoke, and turn this yoke ear to the bottom.
3. Insert cross into yoke so that the trunnion seats
freely into bearing cap.
4. Install opposite bearing cap part way. Make sure
that both trunnions are started straight and true
into both bearing caps.

4A-10 PROPELLER SHAFT
STEP 1
DETERMINE POINT
OF UNBALANCE STEP
2 STEP 3
ADD
HOSE CLAMPS 180 FROM POINT OF UNBALANCE UNlTL THEY BECOME
HEAVY SPOT ROTATE
TWO CLAMPS EQUALLY
AWAY FROM EACH OTHER
UNTIL BEST BALANCE
IS ACHIEVED
1. SHEARED NYLON 2. INJECTION RING INJECTION RINGS REMOVED FROM
BEARING CAP
Figure 4A-16 Production U-Joints-Nylon Injected Ring
Type
1. BEARING CAP 5. SHIELD
2. SNAP RING 6. SEAL
3. FLAT DELRIN WASHER 7. NEEDLE BEARING
4. SPIDER 8. ROUND DELRIN WASHER J10017-4A-F
Figure 4A-17 U-Joints-External Snap Ring Type
1. CROSS PRESS
2.
1 118 (30rnrn) SOCKET TO
SUPPORT YOKE
EAR, BUT MUST
CLEAR BEARING
CAP
J~oo~~-~A-F
Figure 4A-18 Pressing Out Universal Joint Bearing Cap
2. J 9522-5
3. BEARING CAP
Figure 4A-19 Spacer Tool J-9522-5 Installation
5. Press against opposite bearing caps, working the
of the trunnions in the bearing caps. If there
cross all of the time to check for free movement
seems to be a hang-up, stop pressing and recheck

I
1. PARTIALLY INSERTED BEARING CAP J10020-4A-F I
Figure 4A-20 Partially Inserted eari in^ Cap
needle bearings. One or more of them has
probably been tipped under the end of the
trunnion.
6. As soon as one bearing cap snap ring retainer
groove clears the inside of the yoke, stop pressing
and install snap ring into place.
7. Continue to press until the opposite snap ring can
be installed in place. If difficulty is encountered,
strike the yoke firmly with a hammer to aid in
seating snap rings. This springs the yoke ears
slightly.
8. Assemble the other half of the universal joint in
the same manner.
External Snap Ring Type
Disassembly
Figures 4A- 17 thru 4A- 19
These universal joints are of the extended-life
design and do not require periodic inspection or
lubrication; however, when these joints are
disassembled, repack bearings and lubricate reservoir
at end of trunnions with chassis lubricant. Use care not
to loosen or damage dust seals. If dust seals are loose
or damaged, the entire universal joint must be replaced.
1. Remove snap rings. If snap ring does not readily
snap out of the grooves, tap the end of the bearing
cap lightly to relieve the pressure against the snap
ring.
2. Support the propeller shaft in a horizontal
position in line with the base plate of a press.
Place the universal joint so the lower ear of the
propeller shaft yoke is supported on a
1 1/8"
socket. Place Tool J-9522-3 on the open
horizontal bearing cap and press the lower
bearing cap out of the yoke ear. If the bearing cap
is not completely removed, lift Tool
9-9522-3 and
insert Spacer
J-9522-5 between the seal and
bearing cap being removed, as shown. Complete
the removal of the bearing cap by pressing it out
of the yoke.
3. Rotate the propeller shaft and press the bearing
cap out of the yoke.
PROPELLER SHAFT 4A-11
I I Figure 4A-2 1 Installing Retaining Rings - External Type
I 1. STRIKE TUBE YOKE EAR IN THIS AREA I
Figure 4A-22 Seating Universal Joint Snap Rings
4. Disengage cross from yoke and remove.
Assembly
Figures 4A-20 thru 4A.22
1. Install one (1) bearing cap part way into one side
of the yokes and turn this yoke ear to the bottom.
2. Insert cross into yoke so that the trunnion seats
freely into bearing cap.
3. Install opposite bearing cap part way, making
sure both trunnions are started straight and true
into the bearing caps.
4. Press against opposite bearing caps, working the
cross all of the time to check for free movement
of the trunnions in the bearing caps. If there
seems to be a hang-up, stop pressing and recheck
needle bearings. One or more of them has
probably been tipped under the end of the
trunnion.
5. As soon as one bearing cap snap ring retainer
groove clears the inside of the yoke, stop pressing
and install snap ring into place.

$A-1 2 PROPELLER SHAFT
6. Continue to press until the opposite snap ring can
be
installed into place. If difficulty is
encountered, strike the yoke firmly with a
hammer to aid in seating the snap rings. This
springs the yoke ears slightly.
7. Assemble the other half of the universal joint in
the same manner.
1. J 9522-3 CROSS REMOVER
3. J 9522-5 SPACER
2.
J 23498-A DRIVE SHAFT 4. J 35819
INCLINOMETER
Figure 4A-24 Special Tools

REAR AXLE 481-1
SECTION 4B4
BORG WARNER REAR AXLE
NOTICE: All rear axle attaching fasteners are an
necessary. Do not use a replacement part of lesser
important part in that they could affect the
quality or substitute design. Torque values must
performance of vital parts and systems, and/or
be used as specified during reassembly to assure
could result in major repair expense. They must
proper retention of all parts. (There is to be no
be replaced with one of the same part number or
welding as it may result in extensive damage and
with an equivalent part if replacement becomes
weakening of the metal.)
CONTENTS
General Description ............................... 4B 1- I
......... Standard Rear Axle ................... ..... 4B 1 - 1
General Information ............................. .... 4B 1- 1
Limited-Slip Rear Axle .............................. 4B 1-2
Operation
............................................ 4B 1-3
Diagnosis and Testing .......................... 4B 1-2
Axle Noises
..................... .... .................. 4B 1-2
Gear Noise
................................... .... .. 4B 1-4
Bearing Noise
......................... ...... ... 4B 1-4
Rear Wheel Bearing Noise ..................... 4B 1-4
Knock At Low Speeds
....................... ..... 4B 1-4
Backlash Clunk
................................... 4B 1-4
Diagnosis
................................................ 4B 1-4
Pre-Repair Investigation and Trouble
Diagnosis
....................... .. .................... 4B 1-4
...................................... On-Vehicle Sewice 4B 1-7
Carrier Cover and Gasket .......................... 4B 1-7
.............. Axle Shaft ......................... ....., 4B 1-7
Tooth Contact Pattern Test
................... 4B 1-8
Procedure
.................... .. ...................... 4B 1-8
Effects of Increasing Load on
Teeth Contact Pattern
......................... 4B 1-8
Adjustments Affecting Tooth
................................................ Contact 4B 1-8
Effects of Pinion
Postion on Tooth Pattern
............................................... 4B
1-8
Pinion Oil Seal and Companion
Flange Replacement
................... .. ...... 4B 1-8
Rear Wheel Bolt
........................................ 4B 1 - 10
Rear Axle Assembly
................................... 4B I - 10
Unit Repair
............................................... 4Bl-1 1
Drain Rear Axle Assembly ........................ 4B I - I I
Differential Assembly ............................. 4B 1 - 1 1
Hypoid Pinion & Pinion Bearings .......... 4B 1- I I
Four Pinion Standard Differential
Assembly
....................... ... ........... 4B 1 - 1 3
Inspection
............................................ 4B 1 - I:!
Differential Assembly .......................... 4B 1 - 14
Differential Bearing Preload Spacer
................... ...................... Selection .. 4B I - 11
.................................................. Pinion 4B 1 - 15
Operation of Limited Slip Rear Axle
........................................... (Cone Type) 4B 1 - 17
Checking Limited-Slip Function
............ 4B 1 - 17
......................... Limited Slip Differential 4B 1 - 18
.............. Disassembly Inspection Chart 4B
1- 18
......................... Limited Slip Differential 4B I - 1 X
............................................. Specifications
4B 1- 19
Axle Code Identification Chart
............ 4B 1-19
............................................. Special Tools 4B 1-20
GENERAL DESCRIPTION
STANDARD REAR AXLE All parts necessary to transmit power from the
propeller shaft to the rear wheels are enclosed in a
The rear axle assembly is of the semi-floating type salisbury type axle housing (a carrier casting with tubes
in which the car weight is carried on the axle housing.
pressed and welded into the carrier to form a complete The rear axle assembly is designed for use with an open carrier and tube assembly). A removable steel cover drive line and coil springs. The rear axle has a hypoid bolted to the rear of the carrier permits service of the type ring gear and pinion with the centerline of the rear axle without removing the entire assembly from
pinion gear below the centerline of the ring gear.
the car.
GENERAL INFORMATION
NOTICE: Most rear axle service repairs can be
Two pre-loaded tapered roller bearings support the
made with the rear axle assembly in the car, by
hypoid pinion gear in the carrier. The inner race of the
raising the rear end of the car with the rear axle
rear bearing is a tight press fit on the pinion stem. The
hanging on the shock absorbers.
inner race of the front bearing combines a light press
fit to a close sliding fit on the pinion flange end of the
A universal joint connects the rear end of the pinion stem. The outer race of each bearing is pressed
propeller shaft to a companion flange having a splined against a shoulder recessed in the carrier. Tightening
end which fits over and drives the
hypoid pinion gear. the pinion nut compresses a collapsible spacer which

4819 REAR AXLE
bears against the inner race of the front bearing and a
shoulder on the pinion stem. This spacer is used to
enable accurate bearing pre-load adjustment and
maintain a pre-load on both front and rear pinion
bearings, Adjustment of the fore and aft position of the
pinion is obtained by placing a shim between the rear
pinion bearing cup and axle housing. The differential
case is of two-piece construction and is supported in
the carrier by two tapered roller side bearings. Pre-load
rear axle case by inserting shims between the bearings
and the carrier. The rear axle case assembly is
positioned for proper ring gear to pinion backlash by
varying the shim thickness from side to side. The ring
gear is bolted to the case. Two side gears have splined
bores for driving the axle shafts. They are positioned
to turn in counterbored cavities in the case. The four
rear axle pinions have smooth bores and are held in
position by a pinion cross shaft, mounted and locked
in the rear axle case. All six gears are in mesh with each
other and because the pinion gears turn freely on their
shaft, they act as idler gears when the rear wheels are
turning at different speeds. The pinions and side gears
are backed by steel thrust washers.
LIMITED-SLIP REAR AXLE
The operation of the Limited-Slip differential is
the same as the standard differential, except that there
is additional friction provided by the conical clutches.
Under ordinary driving and cornering conditions, the
cones slip, allowing the outside wheel to turn faster
than the inner. Under poor traction conditions, such as
ice, snow, or loose gravel under one driving wheel, the
increased friction provided by the cones increases the
driving torque available to the wheel with the better
traction. The cones are spring loaded to provide the
increased driving torque under extremely low traction
conditions.
Operation
When the vehicle turns a corner, the outer rear
wheel must turn faster than the inner wheel. The inner
wheel, turning slower than the outer wheel, slows its
differential side gear (as the axle shaft is splined to the
side gear) and the differential pinion gears will roll
around the slowed differential side gear, driving the
other differential side gear and wheel faster.
DIAGNOSIS AND TESTING
Many noises reported as coming from the rear
axle assembly actually originate from other sources
such as tires, road surfaces, front wheel bearings, axle
bearing, engine, transmission, muffler or body
drumming. A thorough and careful check should be
made to determine the source of the noise before
disassembling the rear axle. Noise which originates in
other places cannot be corrected by adjustment or
replacement of parts in the differential. It should also
be remembered that rear axle gears, like any other
mechanical device, are not absolutely quiet and should
be accepted as being commercially quiet unless some
abnormal noise is present.
To make a systematic check for axle noise under
standard conditions, observe the following:
1. Select a level smooth asphalt road to reduce tire
noise and body drumming.
2. Check rear axle lubricant to assure correct level,
then drive car far enough to thoroughly warm up
rear axle lubricant, approximately 10 miles.
3. Note speed and RPM at which noise occurs. Stop
car and put transmission in neutral. Run engine
slowly up and down through engine speeds,
corresponding to car speed at which noise was
most pronounced, to determine if it is caused by
exhaust, muffler roar or other engine conditions.
4. Tire noise changes with different road surfaces,
but rear axle noise does not. Temporarily
inflating all tires to approximately 50 pounds
pressure
for test purposes only will materially
alter noise caused by tires, but will not affect noise
caused by rear axle. Rear axle noise usually stops
when coasting at speeds under 30 miles per hour;
however, tire noise continues, but with lower
tone, as car speed is reduced. Rear axle noise
usually changes when comparing acceleration
and coast, but tire noise remains about the same.
Distinguish between tire noise and rear axle noise
by noting if noise varies with various speeds or
sudden acceleration and deceleration; exhaust
and axle noise show variations under these
conditions while tire noise remains constant and
is more pronounced at speeds of 20 to 30 miles
per hour. Further check for tire noise by driving
car over smooth pavements or dirt roads (not
gravel) with tires at normal pressure. If noise is
caused by tires, it will noticeably change or
disappear and reappear with changes in road
surface.
5. Loose or rough front wheel bearings will cause
noise which may be confused with rear axle
noises; however, front wheel bearing noise does
not change when comparing drive and coast.
Light application of brakes while holding car
speed steady will often cause wheel bearing noise
to diminish, as this takes some weight off the
bearing. Front wheel bearings may be easily
checked for noise by jacking up the wheels and
spinning them, also by shaking wheels to
determine if bearings are loose.
6. Rear suspension rubber bushings and spring
insulators dampen out rear axle noise when
correctly installed. Check to see that no metallic
contact exists between the spring and spring seat
opening in frame or between upper and lower
control arm bushings and frame or axle housing
brackets. The track bar and torque arm must be
bolted securely. Metal-to-metal contact at those
points may result in telegraphing road noise and
normal axle noise which would not be
objectionable if dampened by bushings.
AXLE NOISES
After the noise has been determined as being in
the axle by following the above appraisal procedure,
the type of axle noise should be determined to aid in
making repairs if necessary.

REAR AXLE 481-3
1-OUTER BRG. RETAINER
2-WHEEL SEAL
3-WHEEL BRG. CONE
4-WHEEL
BRG. CUP
5-INNER BRG. RETAINER
6-AXLE SHAFT
7-COMPANION FLANGE
8 -PINION OIL SEAL
9-FRONT PINION BRG. CUP
10-FRONT PINION BRG. CONE
1 1-COLLAPSIBLE SPACER
12-PINION NUT
13-DIFFERENTIAL
BRG. CAPS
14-DIFFERENTIAL CAP BOLTS
15-FILLER PLUG
16-REAR COVER BOLTS 17-LUBRICATION
TAG
&
IDENTI FlCATlON TAG
18-REAR COVER
19-REAR COVER GASKET
20-REAR PINION BRG. CUP
21-REAR PlNlON BRG. CONE
22-PINION POSITION
SHIM 23-HYPOID PlNlON
24-DIFF. BRG. SHIM
25-DIFF.
BRG. CUP
26-DIFF. BRG. CONE
27-DIFFERENTIAL ASSY
28-BRAKE BACKING PLATE
29-RING GEAR BOLTS
30-HYPOID
RING GEAR
31-CARRIER &TUBE ASSY
32-WHEEL BOLTS
Fig.
1 Standard Rear Axle