Besides getting the 322 ft lb axle nut off, what is involved in doing the rear wheel bearings? It appears you have to remove not only the hub but the hub carrier. I gather the bearing is pressed into the hub carrier. Is there any trick to this or do I just take off the hub carrier and take it to a shop to have it pressed out?

89 S4


It really isn't that big a job. A Reader's Digest condensed version follows.

Remove the parking brake.
Remove the carrier.
Press the hub out from the rear (which also brings the front inner race with it). The inner race that remains on the hub will look impossible to get off, but will slide off with a little bit of motivation.
Remove that nasty snap ring (which exceeded the capabilities of my wimpy snap ring pliers) and press the rest of the bearing out. Or, bake the carrier in your oven at about 350 for 30 minutes, and it will slide out pretty much on its own.
While hot, drop the chilled new bearing in, replace that snap ring, and press the hub home.

I did this in an afternoon without any specialized tools and just a tad of creative engineering. A shop and press would make it a snap.



At 06:34 AM 10/26/01, Bill Ball wrote:
Besides getting the 322 ft lb axle nut off, what is involved in doing the rear wheel bearings? It appears you have to remove not only the hub but the hub carrier. I gather the bearing is pressed into the hub carrier. Is there any trick to this or do I just take off the hub carrier and take
it to a shop to have it pressed out?

Step 1 - buy the Factory Shop Manual.

Below is a simplified version.

First, if your problem is bearing noise, check that the axle nut is tight. The rear wheel bearings are two-row radial thrust ball bearings, and if the nut is loose, you will get bearing noise. The torque on that puppy is 339 foot pounds. That is 80 pounds on a four foot handle! This bearing replacement method worked for me YMMV.

  1. Put the new bearing (P/N 999.053.050.02, $82.52 Genuine Porsche, $70.16 OEM, plus shipping) in the freezer. FAG Teilenr.: 713612230
  2. Loosen the axle nut. Remove the half shaft (axle).
  3. Remove the caliper - don't take the hose off, just hang it securely on the suspension with a coat hanger wire. Take the brake disk off. Remove the parking brakes, and pull the cable out. On ABS cars, remove the sensor.
  4. Remove the upright (hub carrier) by removing one top bolt and partially removing the large bottom bolt. Be certain that you see and understand how the semi-spherical washers fit the hub faces.
  5. The shock holds the spring - no compressor needed.
  6. Clean everything very well.
  7. Drive the hub from the upright, being careful to avoid damaging the hub.
  8. This will destroy the wheel bearing. I had to cut the inner race off the hub with a die grinder - the book says to press it off.
  9. Don't scar the hub! Clean the hub and put it in the freezer.
  10. Remove the parking brake backing plate and the snap ring.
  11. Clean the upright and put it in the oven at 300 degrees F (per the shop manual) or at 200 degrees F (worked for me).
  12. Carefully (very!) drive the bearing from the upright. Slip the (cold) new bearing in place. Make sure that it goes all the way in - mine just fell in, but I had really chilled the bearing by using dry ice.
  13. Reinstall the snap ring, and be sure (very!) to put the parking brake backing plate back on.
  14. The bearing should now be pretty warm from the upright heat, and the hub should be pretty cold. Be sure that you have the snap ring and the parking brake backing plate in place, and drive the hub in place, supporting the inner race as you do this.
  15. Reinstall everything, being careful to get the parking brake retaining springs hooked over the edge of the holes.
    Torque the axle nut to 339 ft/lbs. I removed the small center cover from my wheel, and torqued it with the wheel on the ground having someone hold the brakes is probably required. I don't know whether the parking pawl in the transmission would stand that kind of load or not.

Good luck!
Wally Plumley


> Have anybody had any experience with bad rear wheel bearings? Right now I having a humming sound like a truck using steel radial tires coming from the rear from 80kms and above. It get louder as I goes faster.
> This is a 5 speed manual. Could it be coming from the Gear Box or Wheel bearing ? The Wheels at the rear is hot to touch compare to the front wheels after a run. Is it the bearing?

Definitely sounds like wheel bearing to me. Try to check if it makes more/less sound turning one way or the other (to get some lateral load on the bearing). I've had to change both rear wheel bearings on my S4, and I think my GTS is slowly getting there as well.



When my rear bearings went it sounded like I was riding on knobby 4x4 tires. The noise would lessen or go away if I was turning (like a 50mph sweeping curve). At first I couldn't really hear until about 40mph but as they got worse you could about feel them a 10mph. Supposedly you can jack the rear up and spin the wheel by hand and feel it, but that didn't work for me. It's not a bad job. I pulled the wheel hubs out, took them and the new bearings to a machine shop and let them press them in (cost was about $48 each). The biggest problem is the axle nut. You may need to rent a 3/4" breaker bar and socket, and buy a pipe. Also a torque wrench to get it back to proper spec.

There is a "keeper" email on my website. Do both at the same time.

John Pirtle
87 a/t 151k


Gruß Micha
Radlagersatz vorn von Ruville 45,80
FAG Teilenr.: 713612230
FAG Nr. 713612130
I agree that it's most likely a wheel bearing. It is something you can test by putting the car on jack stands and running it in gear, or simply keep driving until people start pointing at the flames emerging from the rear or the screech is no longer bearable. I changed mine after a test on jack stands...

It is a job that you might consider taking on yourself, only if you're real handy with tools and can find good instructions - it's far beyond intuition. I don't recall where I found the procedure I used; perhaps in the archives. I wrote it up again, with photos, and submitted it to the digest about 6 years ago, but I don't know if can be located.

The tools required include a 12 ton press to remove the bearing, spouse's permission to use the oven to heat the carrier to about 450F, and the freezer (to chill the bearing overnight), tongs, and a cookie sheet. Hammer or press can never make a new one fit-don't bother trying. As I recall, I also had to locate a very large, odd size metric socket (second trip to town), and I used 4' piece of 2" pipe as a cheater bar. It took me most of a day just locating a press to to use for 5 minutes. It took a 12 ton press to it's maximum limit, so don't bother attempting with anything less. It's an impressive bearing, BTW.

Good time to check the pads, rotors, and CV boots.

'94 968 6 sp
fmly '87 S4

1. You have to take the bearing carrier with the hub in it out of the car.
This is intuitive.

2. Then you have to press the hub out of the carrier. When you do you will get the hub out with one of the two inner bearing races with it.

3. Then you have to use a bearing separator devise and the press to get the other bearing race off the hub.

4. Next, I think, you have to push the bearing, or what is left of in out of the carrier. Here you will need some special tooling which I bought from Harbor Freight for a nominal sum--around $40 as I recall.

5. I don't remember using any heat from an oven, although I have a couple of industrial ovens I use for stuff.

6. I did all or most of this in my 25 ton Hyd press.

7. You push the bearing and hub back in in reverse order. I think that means that you push the bearing back in the carrier and then push the hub back into the bearing using adequate reverse holding blocking and such against the races, as required to keep from pushing an inner race out of the bearing.

8. When you push the hub out and it takes the bearing apart in the process, that basically destroys the bearing. Therefore, don't plan on doing any of this over if you screw up, except with another new bearing.

I wish I had pictures so I could be more informative, but that is what I can offer at this point.

Hope it helps. Jerry Feather


On 1/12/2011 6:57 PM, Joe Elliott wrote:
> Do I understand correctly that (ignoring Wally's advice from yesterday
> to just wait for it to get worse) as quoted below, Wally has done this
> without the use of a hydraulic press?
> Thanks again,
> Joe Elliott


I used heat/cold for everything except for removing the inner race from the hub. For that, I used an abrasive disk in a high-speed die grinder.

Wally Plumley
928 Specialists


Sorry, this is in Dutch, but it does something I'd like to keep as well :)

Codering kogellagers

Hier behandelen wij de meest voorkomende coderingen.
Een lagercode is opgebouwd uit een

Voorvoegsel-Hoofdnummer-Volgcode.A Volgcode.B Volgcode.C / Volgcode.D1 t&m D6


De voorvoegsels komen weinig voor en worden hier niet behandeld.


De hoofdcode bestaat uit cijfers en is gerelateerd aan het soort lagers en de grootte ervan.
Het eerste cijfer geeft het soort lagers weer.

0 = Dubbelrijig hoekcontact lagers
1 = Zelfinstellend kogellagers
2 = Tonlagers
3 = Kegellagers
4 = Tweerijig groef kogellagers
5 = Axiale kogellagers
6 = Groef kogellagers
7 = Hoekcontact lagers
8 = Axiale cilinder lagers
N = cilinderlagers

De rest van de cijfercode is aan de maatvoering van het lager gerelateerd.

Volgcode's A t&m C

De volgcode's A t&m C worden door een spatie gescheiden.
Meestal is er maar een van de 3 code's aanwezig.


Dit zijn interne ontwerpcodes.

A = speciaal ontwerp voor speciale toepassing.(bij kogellagers)
A = Contacthoek 30 Graden bij hoekcontact lagers
B = Contacthoek 40 graden bij hoekcontact lagers
B = Contacthoek kleiner dan 17 graden bij kegel lagers
C = Contacthoek 15 graden bij hoekcontact lagers
C = Contacthoek 20 graden bij kegel lagers
CA= Contacthoek 20 graden bij hoekcontact lagers
D = Contacthoek 28 graden en 30 minuten voor kegel lagers
DJ= Contacthoek 28 graden en 48 minuten en 39 seconden voor kegel lagers
E = Contacthoek 35 graden bij hoekcontact lagers
J = bepaalde maten van een kegellager voldoen aan de ISO standaard


Dit zijn de afdichtings code's.

Geen code           = het lager is open.
RS  = RS1  = RSH    = aan een zijde spatwater dicht.(rubber)
2RS=2RS1 =2RSH   = aan twee zijden spatwaterdicht.(2 zijden rubber)
RSL                          = aan een zijde spatwaterdicht met extra lage wrijving.
2RSL                        = aan twee zijden spatwaterdicht met extra lage wrijving.
Z                               = aan een zijde stofdicht.(metalen plaatje)
2Z                    = ZZ = aan twee zijden stofdicht.(2 metalen plaatjes)


Kooi ontwerp code's

F = Massieve ijzeren kooi
J = Geperste plaatstalen kooi
L = Massieve lichtmetalen kooi
M = Massieve messing kooi
P = Met glasvezel versterkte polyamide kooi
Y = Geperste kooi ven messing plaat

Achter het / teken staan de kenmerken t.a.v. materiaal,
hittebehandeling, nauwkeurigheid,extra speling, smering e.d..


P0 = klasse 0 van de ISO tolerantie-klassen = ABEC 1
P2 = klasse 2 van de ISO tolerantie-klassen = ABEC 9
P4 = klasse 4 van de ISO tolerantie-klassen = ABEC 7
P5 = klasse 5 van de ISO tolerantie-klassen = ABEC 5
P6 = klasse 6 van de ISO tolerantie-klassen = ABEC 3

Extra speling

C1 = Speling kleiner dan bij C2
C2 = Speling kleiner dan normaal
CN = Speling normaal
C3 = Speling groter dan normaal
C4 = Speling groter dan C3
C5 = Speling groter dan C4


I think I stuck my bearings in the freezer the first time I did it, but I had the impression that heating the housing was far more helpful. Does anyone have the math to tell us how much freezing the bearing changes its size, compared with heating the housing?

No math, just a couple of comments...
Housing is aluminum, bearing is steel. Aluminum coefficient of expansion is quite a bit higher than that of steel.
From room temp to 350F (easy if you can catch Ma away from her oven) is a much bigger temp change than room temp to -20F in a freezer. Of course, you could use dry ice and acetone on the bearing, but it might be tough on the grease inside.

I heated the upright, put the bearing in the freezer and the bearing fell freely into the opening.

Wally Plumley
928 Specialists