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Rear Wheel Bearing Replacement - late 944, 968
Last Updated: 08/15/2013
 

Discussion:

 

This procedure will describe the removal and subsequent installation of rear wheel bearings on a Porsche 944 

with aluminum trailing arms (1985.5 & later).  Please note that the specific vehicle documented in this procedure 

is a 1991 944S2. Note: 944 NA’s will have slightly different brakes.

The normal symptom of a failing wheel bearing is a "whoosh-whoosh-whoosh" sound that gets loader and more 

frequent the faster you go.

With this procedure there is no need to perform maintenance one side at a time, as the rear trailing arms are 

NOT being removed and your alignment is NOT being affected.  This job should take the average shade-tree 

mechanic 4-6 hrs.  I had the use of a hydraulic lift so it only took me 3.5 hrs.  The best way to minimize your time 

under the car is too thoroughly familiarize your self with the procedure prior to beginning work.  I read the instructions 

that came with tool B90-P2, the procedure in the Haynes manual and Tabor Kelly’s rear wheel bearing procedure at 

twice each before I began work.

 

Parts:

 

Product


Rear Wheel Bearing


Bearing Removal/Install Tool (B90-P2, B90-3 & B90-3J)


1 Self Locking Axle Nuts


1 Snap Ring


1 Socket Driver, Metric, Triple Square, Long, 8 mm

(good tools are worth the money)



 
 

Procedure:

 

1.   

Prior to loosening the lug nuts is really the best time to loosen the axle nut.  If you have rims that will allow you to remove the center cap you will be able to fit a deep well 32mm impact socket on the axle nut.  Use a good quality air impact gun (the one I used was good for 650ft-lbs off and 450ft-lbs on).  ONLY LOOSEN THE AXLE NUT!  DO NOT REMOVE IT WITH THE WEIGHT OF THE VEHICLE ON THE AXLE.  Throw the nut away, it cannot be reused.

2. 

Loosen lug nuts, support car securely, finish removing the axle nut and then Remove wheel.

3. 

Remove axle to transaxle bolts. There should be 6 (8mm) of them. They are often referred to as "three square" or "cheese-head" bolts because of their unique bolt head. The same bolts are used in Volkswagens so finding the tool should not be too hard. (Snap-on.com has it, you want the one with the longer bit in order to clear the CV joint boots).  Be very careful that the head is completely clean of contaminants before you try to unscrew it, otherwise you will strip the head.  Using a cheap ‘three square’ bit typically results in ruining the bit and/or the head of the bolt.  I recommend spending the money for a good quality bit.  [Craftsman or Snap-on]

4. 

On the S2 you will have to remove the entire axle and it is still a tight fit to slip the inboard CV joint forward and up out of the coupling.

5. 

Remove axle. On the exhaust side of the car you will have to push the inside CV-joint up above the transmission to get the axle out of the hub.

5a.

Be sure to keep the CV joints clean if you don’t plan to repack them.  Mine were in good shape so I place large plastic bags over the CV joints to keep contaminants from getting in the grease.

6. 

Remove the brake line from the brake caliper. Unless you feel lucky, make sure to use a flare nut wrench. To stop all the brake fluid from draining out of your system, depress the brake pedal slightly. You could prop a large wrench or piece of wood against the seat if you slid it forward or you can put a small rubber cap or clamped off rubber hose over the tip.

7. 

Remove the brake caliper, it should be held on to the trailing arm with 2 -19mm bolts.  Remove the brake pad wear sensor from the junction box at the bottom of the baking plate.  This is quicker and easier and will prevent damage to the brittle wear sensors by leaving them in the pads.  (On the S2, non-S Turbo and non M030 968 be careful not to lose the spacer washers between the trailing arm and the inside of the caliper during removal.)

8. 

Remove the brake rotor. It will be held on to the hub with one or two Phillips head screw. They are supposed to be torqued to 7 ft-lbs but are often rusted tight from heat and weather exposure.  If you use an impact tool with a hardened Phillips head bit they will come right out.  Just make sure you don’t hit your hand with the hammer.  Typically, if you try to remove them with a normal screwdriver you are going to strip the head you will end up drilling off the head and removing the rest with vice grips.

9. 

Remove the aft most parking brake shoe retaining spring by pressing in and unhooking the spring from the baking plate.  Remove spring from shoe.  This is done so the hub removal tool will lay flush against the parking brake shoes.

10. 

Use either a soft mallet or a large brass drift and tap out the stub axle.  ***All mine required was a light tap, NOT a pounding but YMMV.  If you hit it too hard you will shoot your stub axle across your garage. J

11. 

Assemble the bracket (B90-3) and horseshoe (B90-3J) and place the  horseshoe/bracket behind the hub flush against the aft parking brake shoe.  Now slide the threaded rod through the bracket with the thrust washer (large silver washer) contacting the outside of the bracket.  Place the smallest disc in the kit (only two are provided) on the open end of the threaded rod and thread on the elongated pusher nut.  Thread the nut on by hand and snug up the entire assembly so it will remain straight when you start using the wrenches on it.

ATTENTION!!! - CUSTOMER FEEDBACK: The problem is in step 11 where it says to fit the smallest extractor washer and then the elongated nut and commence the extraction. At that point you are tryiing to extract the hub and you should not use any extractor washer as the elongated nut alone will press the hub out. By using the small extractor washer at that point you end up trying to press the bearing out while the big circlip is still in place. It does not work and the end result is that you will bend the 1/2" steel bar that the extractor thrust washer sits against and the thrust washer itself will sustain damage. Ask me how I know. BTW I confirmed the correct use of the tool from the instructions that accompany the extractor tool. [Wayne Greham]

12. 

Using a 23mm open end wrench “HOLD” the elongated nut, DO NOT TURN IT.  All turning is to be done with the threaded rod itself as that is what the thrust washer is there fore.  Place a 23mm impact socket on the head of the threaded rod and turn clockwise until the hub in extracted from the bearing.  A portion or possibly all of the bearing’s inner race may remain attached to the hub.  Don’t worry, Porsche knew this would happen and placed two nice notches in the shaft portion of the hub to facilitate removal of the race.

13. 

Take a short pulley/gear puller and remove the inner portion of the bearing still attached to the hub.

14. 

Remove the threaded rod from the bracket/horseshoe. 

15. 

Take large snap-ring pliers and remove large snap-ring.  (You really need a very good pair of snap ring pliers for this job as it will probably be the largest snap ring you ever remove/install).  

16. 

Insert the threaded rod through the centering disc and then slide on the spacer sleeve and adapter ring.

17. 

Insert the threaded rod through the bearing from the outboard side of the axle.

18.

Place the largest disc (#12) on the threaded rod and thread on the elongated nut to snug up the assembly. 

19.

Ensuring that the assembly remains level and straight apply torque to the head of the threaded rod while holding the elongated nut.  This will drive the old bearing outboard into the spacer sleeve. 

20.

Disassemble bearing remover and throw away old bearing!  Congrats!  You’re half way there.

21.

Clean out bearing housing (trailing arm) and clean hub shaft.

22.

Place largest disc (#12) on threaded rod (flat side toward trailing arm) place new bearing against the bearing housing (there is usually enough friction to hold it in place).  Place adapter ring, spacer sleeve, and centering disc on the threaded rod on the inboard side of the trailing arm.  Place the elongated nut on the rod and snug it up.

23.

Apply torque to the head of the elongated rod.  Periodically stop to ensure that the new bearing is going into the housing straight.  Drive the bearing into the housing (trailing arm) by continuing to turn the rod while holding the elongated nut. 

24.

Once the new bearing is flush with the housing, replace the snap-ring.  (I bought new ones but if you haven’t damaged yours you could reuse them)

25.

Place the hub in the center of the bearing (it should insert a little bit, enough to hold it in place).

26.

Slide the largest disc (#12) onto the threaded rod.  Insert the assembly through the hub, bearing and trailing arm and slide on the small disc (#14) and thread on the elongated nut and snug it all up.

27.

Apply torque to the head of the threaded rod to drive the hub into the bearing.  ***YOU MUST USE THE SMALLEST DISC ON THE ‘INBOARD OR TRANSMISSION SIDE’ OF THE BEARING.  If you don’t you will destroy your new bearing trying to insert the hub.

28

Congratulations Again!!  You are finished driving things into or out of the bearing or trailing arm!! 

29

Re-insert the stub axle (should slide back into the hub easily) place the spacer washer on the axle and thread on the NEW AXLE NUT.  YOU MUST USE A NEW SELF-LOCKING NUT!  They are available from any Porsche dealer for ~$5.  Plan ahead though they may have to special order it, my Porsche dealer doesn’t stock them.

30

At this point, I recommend using a large pry bar between the wheel studs (in order to hold the hub still) and manually torque the axle nut to 250ft-lbs.  I decided on 250ft-lbs because that was the highest I personally could get with one hand on the pry bar and one hand on the torque wrench.  You can set final torque once the car in back on the ground.

31

Re-install your axle, brake disc, caliper, brake-wear sensor, bleed the brakes, and re-install wheel.

32

Lower car from jack stands or lift.  You are going to need all of the cars weight on the wheel for this last part.

33

Place the deep well 32mm impact socket on the axle nut and torque to 368ft-lbs.  You may have to rent a torque wrench capable of measuring torque this high.  Also, it is likely that it will be a ¾” drive torque wrench so, either buy a ¾” drive 32mm impact socket or use a ¾” to ½” adapter.

34

Don’t forget to properly torque your lug nuts to 96ft-lbs.

 

 

Torque Specs:

Item

Specification

Axle Nut

368 ft-lbs (500 Nm)

Axle to transaxle bolt

31 ft-lbs (42 Nm)

Caliper to brake back plate or trailing arm.

63 ft-lbs (85 Nm)

Lug nuts

96 ft-lbs

 

 

 

 

 

 

 

 

 

I would like to thank Tabor Kelly for his wheel bearing procedure from which I borrowed a great deal of mine.  I would also like to thank all the people who post on Rennlist for their input and advice on all things Porsche.

 

Credits:    Max Lohman
 
Last Modified: 2003-11-24         


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