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DRIVE-TRAIN
SERVICE
Tool and Material Checklist:
- Wheel chocks
- Pipe wrench
- Jack and Jack stands
- Pry bars
- Drain pan
- Two or three-Jaw gear
- Box wrench
- Masking tape
- Bench vise
- Grease
- Inch-pound torque wrench
In this booklet, two common drivetrain service
procedures for rear-wheel-drive cars are discussed
in detail. Although a number of drivetrain problems require professional service, both universal
joint and pinion seal replacement can be handled
by the willing do-it-yourselfer.
REPLACING A
UNIVERSAL JOINT
After initial squeaking, the two main symptoms
that Indicate a universal joint might be worn are:
- A metallic knock when the car is put in gear
- A clunking noise when the accelerator is depressed and released at about 30 mph
To confirm that a joint is bad, grab the drive
shaft and try to move it from side to side, then up
and down. If you see any signs of looseness in the
shaft and joint, the joint is worn and should be
replaced.
REMOVING THE DRIVE SHAFT
To replace a U-joint, the drive shaft must be removed first. To do this, proceed as follows:
1. Park the car on a level surface.
2. Place wheel chocks in front of the front tires.
3. Lift the rear of the car and place a pair of
safety jack stands under the rear axle housing. Be
sure that the stands are securely in place.
4. Place a drain pan under the transmission's
rear seat.
5. Use chalk to mark the pinion flange location
on the differential housing and the drive shaft. This
will enable you to reinstall the shaft in the same
position.
6. Using a box wrench, remove the four bolts
and retaining straps (or the two U-bolts) that secure the shaft to the pinion flange. To reach all the
bolts, shift the transmission into neutral and rotate
the shaft with your hands.
7. In some cases, the nuts are locked in place
with metal tabs. These tabs must be pried away
from the nuts before a wrench can be placed over
them.
8. Use a large screwdriver to pry the U-joint
away from the pinion flange.
9. Wrap masking tape around the u-joint to hold
the bearing caps In place.
10. Pull the drive shaft straight back until the
slip yoke on the front end of the drive shaft disengages from the transmission's
output shaft.
REMOVING THE FRONT JOINT
1. Clamp the slip yoke in a vise and support the
other end of the drive shaft.
NOTE: Never clamp
the drive shaft's tubing in a vise. This could distort
the tubing and throw the drive shaft out of
balance.
2. Remove the four retaining rings that hold the
U-joint cross in the yoke and drive shaft ears. The
rings can be located on either the inside or outside
of the bearing caps.
3. Some U-joint bearing caps have plastic retainers. To disassemble the U-joint, these retainers
must be broken when the bearing caps are removed. This type of joint cannot be reassembled,
so the entire assembly will have to be replaced.
4. Open the vise wide enough to accommodate
the width of the drive shaft plus the length of a
socket on either side of the drive shaft.
5. Find a socket that is wide enough for a bearing cap to slide into it (usually 1") and place it over
one of the caps. On the opposite cap, place another socket that is small enough to slide into the
drive shaft's bearing cap hole (usually 9/16").
6. Tighten the vise so that the 9/16" socket
pushes the bearing cap on the opposite side into
the 1" socket.
7. Loosen the vise and remove the sockets and
the protruding bearing cap. If necessary, use vise
grips.
8. Turn the drive shaft over in the vise and remove the opposite bearing cap in the same
manner.
9. Remove the remaining bearing caps, then remove the U-joint cross from the slip yoke.
10. Inspect the old U-joint to see if one or more
of the caps is loose or galling on the cross. If so,
the needle bearings within have failed and must be
replaced.
REMOVING THE REAR JOINT
The rear joint is removed in basically the same
manner as the front joint. However, the cross U-joint is usually bolted directly to the pinion flange,
so all you have to do is press the joint out of the
drive shaft.
INSTALLING THE NEW JOINT
Before installing the new joint, remove any burrs
or rough spots from the inside of the holes in the
yoke and drive shaft ears. Also, be sure to clean
the retaining ring grooves so the rings seat
properly.
1. Carefully remove all the bearing caps from
the new U-joint.
2. Put some grease inside each of the bearing
caps to hold the needle bearings in place during
the installation, If the needle bearings are knocked
over inside the caps, you will not be able to install
the new joint.
3. Position the new U-joint cross inside the slip
yoke so that it extends out of one of the bearing
holes in the yoke.
4. Start one new bearing cap on the U-Joint
cross and guide it into the yoke. Be sure the U-joint cross and bearing cap are not cocked to one
side.
5. Carefully place the assembly in a vise. Use
the vise to press the bearing cap partially into the
yoke ear.
6. Remove the yoke from the vise.
7. Push the U-joint cross so that it protrudes
from the other side of the yoke.
8. Install a bearing cap over the protruding U-joint cross.
9. Place the assembly in the vise and tighten the
jaws so that the bearing caps are pressed into the
slip yoke. To ensure that the U-joint cross moves
freely in the bearings, turn it as you tighten the
jaws. If any resistance is encountered, stop tightening the vise and check to see if the needle
rollers have tipped under the end of the U-joint
cross.
10. Install the new retaining rings. To do this,
bearing caps might have to be pressed in further.
Place a 9/16" socket on each cap; press until one
retainer groove appears above the bearing cap or
inside the yoke. Install the retainer ring, then remove the socket on the side where the ring was
installed. Continue to press until the opposite ring
can be snapped Into place.
11. Install the U-joint cross in the drive shaft
ears in the manner described above.
INSTALLING THE
DRIVE SHAFT
1. Slide the slip yoke into the transmission output shaft splines, pushing forward on the shaft
until the yoke is seated firmly.
2. At the rear of the car, line up the chalk marks
on the drive shaft and pinion flange.
3. Connect the rear U-joint to the pinion flange
yoke. Be sure that the bearing caps are fully
seated in the pinion flange.
4. Install the U-bolts or retaining straps. Use a
box wrench to tighten the retaining nuts or bolts.
5. Remove the safety jack stands and lower the
car.
REPLACING A PINION SEAL
The pinion seal of a rear-drive car encircles the
pinion shaft. If it is defective, gear lube will leak
from the front of the differential.
REMOVING THE OLD SEAL
1. Park the car on a level surface and place
wheel chocks in front of the front tires.
2. Lift the rear of the car and place a pair of
safety jack stands under the rear axle housing. Be
sure that the stands are securely in place.
3. Place a drain pan under the transmission slip
yoke seal.
4. Use chalk to mark the drive shaft, the pinion
flange, and the end of the pinion stem to which the
pinion flange is attached. This will ensure that the
drive shaft and flange can be reinstalled in the
same position.
5. Use a box wrench to remove the four bolts
and retaining straps (or the two U-bolts) that secure the shaft to the pinion flange. To reach all the
bolts, shift the transmission into neutral and rotate
the shaft with your hands.
6. In some cases, the nuts are locked in place
with metal tabs. These tabs must be pried away
from the nuts before a wrench can be plated over
them.
7. Use a large screwdriver to pry the U-joint
away from the pinion flange.
8. Tie the drive shaft to the exhaust pipe or
chassis.
9. Wrap masking tape around the U-joint to hold
the bearing caps in place.
10. Remove the rear wheels and brake drums to determine how much the pinion bearing is
preloaded. You must know this to reassemble the unit.
11. Using an. inch-pound torque wrench, turn
the pinion shaft nut. Record how much force is
needed through several complete rotations.
12. Hold the pinion flange with a large pipe
wrench so that it won't turn; then remove the pinion flange nut. On some cars the pinion flange can
be held in place by screwing a couple of bolts into
the companion flange and wedging a pry bar between them.
13. Clean the area around the pinion flange and
seal.
14. Place a drain pan under the flange.
15. Use chalk to mark the pinion flange and pinion shaft in relation to one another.
16. Remove the pinion flange using a two-jaw
gear puller.
17. Check the pinion flange for a seal groove,
nicks, or other marks. If the seal surface is damraged, the pinion flange must be replaced;
otherwise, the new seal will leak.
18. Use a small pry bar or a blunt chisel to remove the seal from the carrier.
19. Remove any burrs from around the carrier
bore to prevent leaks around the seal.
INSTALLING THE NEW SEAL
To install the new seal, use a driver with a diameter that matches that of the seal. Although
there are special tools available for installing seals,
a smooth piece of pipe backed by a piece of wood
can be used in most instances.
1. Apply a small amount of rear-end lube to the
pinion-flange area and splines.
2. Use the alignment marks on the pinion shaft
and flange to install the flange in its original
position.
3. Install a new nut on the pinion shaft and
tighten it while holding the pinion flange. Occasionally rotate the pinion while tightening the nut
and take frequent preload readings, turning the
pinion nut and shaft with the inch-pound torque
wrench.
NOTE: If the torque readings vary during
a complete revolution, something is binding and
must be corrected.
4. Stop tightening the nut and taking readings
when the recommended preload reading for your
vehicle is obtained. It is important to keep in mind
that you cannot reduce preload by backing off the
pinion nut. If the desired preload is exceeded, a
specialist will have to finish the job.
5. To reinstall the drive shaft, line up the chalk
marks on the drive shaft and the pinion flange.
6. Connect the rear U-joint to the pinion flange
yoke. Be sure that the bearing caps are completely
seated in the pinion flange.
7. Install the U-bolts or retaining straps. Use a
box wrench to tighten the retaining nuts or bolts
securely.
8. Remove the safety jack stands and lower the
car.
9. Add lubricant to the differential to bring it to
the proper level. If necessary, add transmission
fluid
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