924/944/968 Frequently Asked Questions

944 Constant Velocity (CV) Joint Maintenance

The following FAQ was created by Ed Gibbs. 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 located?

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 stage.

What is the CV Joint Removal/Cleaning/Inspection/Replacement procedure?

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!

Tools required

  Note: 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 joint bolts.  
  Note: Some cars may have had the 12 point bolts replaced with allen head bolts. Check yours first.  
  Note: External 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:

Plier jaws:

Consumables

Procedure

  1. Raise the rear of the car and support it securely with jack stands or ramps.
  2. Disconnect the battery and chock the front wheels (VERY IMPORTANT!).
  3. Put car in neutral with parking brake off.
  4. 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!).
  5. Mark axle with scribe or paint to indicate which end is inboard and the direction of rotation.
  6. 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.
    Note: If 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.  
    Note: If you strip a bolt head, use vise grips to remove the bolt. If it breaks, remove the stub after removing the entire assembly.  
  7. Repeat step 6 for bolts holding CV joint to wheel hub.
  8. 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 surface.
  9. Work around metal collars holding boots to joints with hammer and punch or screwdriver to gently separate collars from joints.
  10. 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 separated.
  11. 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.
  12. Push axle out of joint with thumbs, or if necessary drive out using a hammer and a small socket.
  13. Work concave washer off axle using slip joint pliers or vise grips (see illus. in Haynes book).
  14. Carefully pull boot off axle.
  15. 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.
    Warning: Read 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).  
  16. 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.
  17. Dry all parts thoroughly, removing ALL traces of solvent. Inspect carefully for wear, burned areas, scoring, etc. If in doubt, replace joint.
  18. Inspect boots carefully for cracking, cut, rips, etc. If in doubt, replace.
  19. Apply a small amount of CV joint grease to the inside of the boots. Work into the folds of the boots with your fingers.
  20. 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.
  21. 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.
    Note: Washer goes on like this: \|AXLE|/, not like this: /|AXLE|\.  
  22. 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.
  23. 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!
  24. 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.
  25. Reinstall snap rings with snap ring pliers, or use small screwdriver and much cussing.
  26. Tap on end of joint with hammer and deep socket (or partially opened vise grips) to ensure snap ring is fully seated in groove.
  27. Thoroughly pack CV joints with CV joint grease, working in between races and ball bearings. Use plenty - grease is cheap, CV joints aren't!
  28. Clean any old grease out of flanges on wheel hub and transaxle. Fill with fresh CV joint grease to provide extra grease for joint.
  29. Reinstall joint/axle assemblies and tighten bolts finger tight. When reinstalling axles ensure that direction of rotation is the same as when removed.
    Note: If any bolts even started to strip during removal, replace them or you’ll never get them off the next time!  
  30. Torque bolts to 30 ft-lbs. using 8 mm 12 point Allen head socket and torque wrench.
    Note: Ensure that there is no grease or dirt in the bolt head recesses or incorrect torque readings may result.  
  31. Rotate wheel and check for unusual noises, binding, etc.
  32. Repeat steps 1-32 on other side of vehicle.
  33. Apply parking brake and put vehicle in gear. Reconnect the battery.
  34. Lower vehicle.
  35. Road test vehicle carefully, checking for unusual sounds.

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