924/944/968 Frequently Asked Questions
944 Constant Velocity (CV) Joint Maintenance
The following FAQ was created by
Errors, omissions, and bug reports are appreciated, as are constructive criticisms.
I offer no guarantee as to completeness or
accuracy of the information contained herein. As with any
procedure, use your common sense, and if something doesn't look
right, stop and find out why!
What are CV joints and where are they
CV Joints are similar to the universal joints
used on some cars. They connect the transaxle to the axles and
the axles to the drive wheels, transferring power while allowing
for up and down motion of the suspension. If you look under the
rear of your 944 you will see black rubber boots on the either
end of both axles. These boots protect the CV joints from dirt
and keep the grease that lubricates them from running out.
What maintenance do CV joints require?
The rubber boots protecting the CV joints
should be inspected at each oil change, and replaced if any cuts,
cracks, or damage is noted. A leaking boot will allow the grease
to run out, resulting in very rapid failure of the CV joint.
Replacement of the boot requires removal of the joint, but is
well worth the effort.
The joints should be periodically removed,
cleaned, inspected, repacked with grease, and reinstalled. In
addition, some people recommend switching the joints from left to
right and vice versa on a periodic basis. This is due to the fact
that wear on the joints tends to be directional, based upon the
loading imposed during forward travel. By swapping the joints to
even the wear their life can be extended. Since new CV joints
from Porsche cost approx. $150 each and there are four CV joints
this seems like a worthwhile idea.
How do I know if my CV joints are bad?
The most common symptom is a clicking noise
heard from the rear of the car, especially during cornering. The
noise will usually come from one side only, usually the side
opposite the direction of the turn. If you have any doubt, take
them apart and check them out yourself.
How long does it take to remove, clean,
repack, and reinstall all four joints?
First time, budget 7-8 hours, barring too many
problems. Will take considerably less time with practice. The
process is not difficult, provided the proper tools are available
(see below) but patience is required, especially in the cleaning
What is the CV Joint
A suggested procedure follows. This procedure
assumes that you will be cleaning packing, and reusing the same
CV joints. If you know that your CV joints are bad it may be
cheaper to buy an entire axle assembly with both CV joints,
boots, and grease already installed. These are available for
about $200 rebuilt or $300-$400 new.
The Haynes 944 book has a very good description
of the process, and it should be consulted first. If you don't
have it, get it!
- 8 mm 12 point Allen head socket
||This tool is
available from Performance Products, Automotion and other
sources for about $20. Your local auto parts store may
carry a cheaper version (look in the VW tools) for about
$6.50. The cheap version requires you to use your own 8
mm socket, but is nice because it is about three inches
long, to help clear the rubber boot when removing the CV
||Some cars may
have had the 12 point bolts replaced with allen head
bolts. Check yours first.
- Breaker bar
- Torque wrench capable of measuring 30
- Slip joint pliers or large vise grips
- Various sized sockets
- Punch or screwdriver
- Scribe (carbide-tipped)
- Parts cleaning tray
- Parts cleaning brushes
- External snap ring pliers (Snap-On part
number PR-40, $22.95 or equivalent).
Circlip pliers (for clips with holes) may work, but only
with extreme difficulty and much cussing. The correct
type of pliers has two undercut metal tabs facing outward
that hook under the ends of the ring and expand it. They
look like this:
Tabs - rectangular cross-section, not round:
- Solvent (mineral spirits)
- Spray brake cleaner
- Rags/paper towels (lots!)
- CV Joint grease (moly based grease, available at auto parts stores)
- Raise the rear of the car and support it
securely with jack stands or ramps.
- Disconnect the battery and chock the front
wheels (VERY IMPORTANT!).
- Put car in neutral with parking brake off.
- Clean all dirt, oil, and mung from center
recesses on the 12 point allen head bolts holding the CV
joints to the transaxle and wheels on one side of vehicle
using spray brake cleaner and a pick or nail (IMPORTANT -
do a good job or you may strip out the head when trying
to loosen the bolts!).
- Mark axle with scribe or paint to indicate
which end is inboard and the direction of rotation.
- Hold wheel from rotating with foot while
using 8mm 12 point allen head socket and breaker bar to
just loosen all six bolts holding CV joint to transaxle,
rotating wheel as necessary to bring each bolt into
position. It may be helpful to tap the allen head socket
into the bolt recess with a hammer.
bolts are very tight, apply parking brake or put
car in gear to hold wheel, loosen bolt, then
release brake and put in neutral to rotate wheel
for each bolt.
you strip a bolt head, use vise grips to remove
the bolt. If it breaks, remove the stub after
removing the entire assembly.
- Repeat step 6 for bolts holding CV joint
to wheel hub.
- Back 5 of six bolts on each CV joint out
completely. While supporting CV joints back out remaining
bolts and carefully remove CV joints/axle assembly from
vehicle. Place assembly on newspapers on a clean, flat
- Work around metal collars holding boots to
joints with hammer and punch or screwdriver to gently
separate collars from joints.
- Wipe grease from ends of joints, and mark
across axle, inner, and outer races with scribe to mark
orientation of parts (IMPORTANT!) Make one mark on inner
joint, two on outer, to identify parts if they become
- Use snap ring pliers to remove snap ring
on end of axle. Or, use circlip pliers to spread ring,
small screwdriver to pry ring up, mouth to curse, and
eyes to watch where ring lands if you are lucky enough to
get it off.
- Push axle out of joint with thumbs, or if
necessary drive out using a hammer and a small socket.
- Work concave washer off axle using slip
joint pliers or vise grips (see illus. in Haynes book).
- Carefully pull boot off axle.
- Disassemble joint by tilting inner race
until inner race, ball bearings, and retaining ring come
out. Keep parts together and label inner or outer and
passenger or driver side.
and observe all safety precautions on solvent
packaging. Do not use solvents near open flame or
sources of ignition. Do not smoke while using
solvents! (The Lawyers made me say this).
- Clean all parts with solvent and brushes,
including boots (if being reused) and axles. Take your
time and do a good job. Some greases are incompatible.
Unless you KNOW that you are using the same formulation
of grease as was in your joint previously, try to get rid
of ALL the old grease. Save solvent for proper disposal.
- Dry all parts thoroughly, removing ALL
traces of solvent. Inspect carefully for wear, burned
areas, scoring, etc. If in doubt, replace joint.
- Inspect boots carefully for cracking, cut,
rips, etc. If in doubt, replace.
- Apply a small amount of CV joint grease to
the inside of the boots. Work into the folds of the boots
with your fingers.
- Apply a small amount of CV joint grease to
the ends of the axles, and carefully work the boots down
over the axles. The boots should go over the ribs
machined into the axle to hold them in place.
- Reinstall the concave washers, using a
deep socket to drive them on. Or, use a pair of vise
grips, opened enough to sit on the washer without
touching the axle, and hammer on the vise grips. Washer
must go all the way to the bottom of the splined area.
goes on like this: \|AXLE|/, not like this:
- Reassemble joints by putting inner races
inside retaining rings, and snapping ball bearings into
slots on retaining ring. Insert inner race assembly into
outer race by tilting in, ensuring that marks made during
disassembly line up.
- Test operation: Inner race should freely
rock back and forth, while retaining ring remains locked
to outer race. If inner race is locked to outer race and
retaining ring tilts freely, then joint is assembled
improperly. Correct before use!
- Lightly grease splines on axle and center
holes on joints. Reassemble joints onto axles. If
desired, swap inner and outer joints so that direction of
rotation of the joints is reversed. Some claim that this
will extend the life of the joints.
- Reinstall snap rings with snap ring
pliers, or use small screwdriver and much cussing.
- Tap on end of joint with hammer and deep
socket (or partially opened vise grips) to ensure snap
ring is fully seated in groove.
- Thoroughly pack CV joints with CV joint
grease, working in between races and ball bearings. Use
plenty - grease is cheap, CV joints aren't!
- Clean any old grease out of flanges on
wheel hub and transaxle. Fill with fresh CV joint grease
to provide extra grease for joint.
- Reinstall joint/axle assemblies and
tighten bolts finger tight. When reinstalling axles
ensure that direction of rotation is the same as when
any bolts even started to strip during removal,
replace them or youll never get them off
the next time!
- Torque bolts to 30 ft-lbs. using 8 mm 12
point Allen head socket and torque wrench.
that there is no grease or dirt in the bolt head
recesses or incorrect torque readings may result.
- Rotate wheel and check for unusual noises,
- Repeat steps 1-32 on other side of
- Apply parking brake and put vehicle in
gear. Reconnect the battery.
- Lower vehicle.
- Road test vehicle carefully, checking for