[Paul W]

I installed my control arm to body bushings tonight and the new power steering rack bushings....both were worn.



One thing that I found when I brought the car in for an alignment a few weeks ago was that there was wheel bearing clearance. Most likely excessive. I went to adjust it tonight and it seems that it is adjusted correctly, but I don't know what it should feel like.



This is what I have:

• With the wheel on and the car jacked up, if I grab the top of the tire at 12 o'clock and rock it back and forth, I would say I have about 1/64" - 1/32" of play in the bearing. I can feel it basically rocking on the inner thrust face then to the outer thrust face of the bearing. It is ever so slightly loose. No more play than slight movement between thrust faces when thrusting in or out (insert inkedupfatboy joke here).
  
  

• If I spin the wheel, it stops pretty quickly, like 1/4 to 1/2 turn max....so it's not super loose.
  
  

• If I take the wheel off, I cannot get any noticeable play in the hub by moving the brake rotor.
  
  

If you go to Clark's Garage it states:

1. After the grease cap is removed, use the medium flat tip screwdriver to turn the bearing thrust washer (just behind the locking collar). When you try to turn the washer ensure that the screwdriver is not resting on the locking collar or on the hub. If the washer spins freely or if you are unable to turn the washer using the screwdriver, the wheel bearing needs to be adjusted.
   
   
2. If adjustment is required, loosen the locking collar Allen head bolt using a 6 mm Allen head wrench or long Allen head socket. To get the wrench into the head you'll have to turn the hub until the detent in the lip of the hub lines up with the head of Allen bolt.
   
   
3. Once the Allen head bolt is loosened, turn the locking collar as necessary to achieve proper adjustment on the bearing (as described in the previous steps). If the washer turns too freely, turn the locking collar in the clockwise direction to tighten the bearing. If the washer is too tight, turn the collar in the counter-clockwise direction to loosen the bearing.
   
   

I can't say that I could get the thrust washer to move, does it have an indent on it that splines to the shaft?





The bearing does not seem loose to me, and I remember reading somewhere when I did my Alfa Romeo bearings earlier this year that they should have a very small amount of play when cold so they can expand when hot.



Anybody have any experiences that they can share? I can say that the steering rack rubber bushings were VERY worn (at least on the driver's side) and I remember feeling A LOT more bearing clearance before I changed them. Like a crazy amount on the driver's side. I wonder if the loose bushing contributed to that.



Thanks!

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[Inkedupfatboy]

No (I don't have experience) but I would think you are going to get more play out of it with the tire on it as the tire is acting as a lever and has more mass so it will produce what seems to be more slop.



I use to love it when the garage would jack my truck off the ground two inches and put a pry bar under the tire and lift up on it and tell my my ball joints were 0.030 of an inch worn, when I could see the entire car lift up - If you can feel 0.030's with a pry bar, I would eat my hat.

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[flash]

.030" in a ball joint is HUGE. that's really easy to feel. you can usually feel ball joint play pretty easily down to around .010" if there is grease in them. less if there isn't.



as for the wheel bearings, i see no reason to set them any differently than any other wheel bearing. they are typical design. i set them for zero play, but no load, and pack them heavily with a high temp waterproof grease.

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[Cloud9...68]

This is a nice video showing how to change and adjust the wheel bearings on a 944 (the procedure for a 968 is identical). This is what I followed, and it seemed to work well, but I have no point of reference, as it's the first one I've ever done:



http://www.youtube.com/watch?v=O2lUqvga0n0



By the way, you mentioned that when you turn the wheel, it stops pretty quickly. Do you think that's being caused by the wheel bearing, or some grab by the brakes? Mine acts the same way, and it looks like my brake pads are always touching my rotors, with no clearance whatsoever. However, my brakes aren't hot after a drive, so they can't be dragging too badly. Any idea what's "normal" for how long a wheel should spin after giving it a turn by hand?

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[MB968]

[quote name='Paul W' timestamp='1383792549' post='151808']

The bearing does not seem loose to me, and I remember reading somewhere when I did my Alfa Romeo bearings earlier this year that they should have a very small amount of play when cold so they can expand when hot.



Anybody have any experiences that they can share? I can say that the steering rack rubber bushings were VERY worn (at least on the driver's side) and I remember feeling A LOT more bearing clearance before I changed them. Like a crazy amount on the driver's side. I wonder if the loose bushing contributed to that.



Thanks!

[/quote]



I can't see any connection between worn rack bushings and loose wheel bearings unless the sudden stop when the rack moves back and forth and hits a hard stop puts a little more intertia load from the tire on the wheel bearing. But, the disc from the brakes will also impede this, so I don't see it making much difference.



Setting a tapered roller bearing a little loose is common for most designs that include tapered rollers. Usually the non-rotating part is a better heat sink, and thus will run cooler than the rotating part of the assembly. So, by setting the fit a little loose, (as per the Porsche manual), as the bearing/hub heats up, and expands axially, the looseness will be taken up. This type of bearing will take a lot of preload since the rollers have line contact with the mating parts. The intent of how loose you set it when cold is to keep the preload when it warms up below the max. that the bearing will take. Porsche's recommended setting presumably comes from their experience on what works on this car.



However, the washer on the 968 (see attached pic) does have a tab, so it really can't rotate as per the Porsche manual. I doubt this part detail changed since you'd want a non-rotating part between the bearing inner race, and the nut. Since it has the tang, I'm not sure how exactly I will set this when I get around to installing the part in the next few days. (Due to taking a part off my car for Eric's during the Enduro Race, I discovered that my car was missing this part, which is why I have one to take a picture of.) I'll try the screwdriver routine to see if I can make it move back and forth, or? If this doesn't seen to work, I may use some .001 feeler stock between the rear of the nut, and the washer to insure there is a certain amount of gap.

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[Paul W]

Thanks a lot for the info! I would say that my wheel bearings are good to go as-is. Now it's time to clean up the bottom of the car, install the batwing (front apron) that Cloud sold me a while back (finally have the hardware to install it) and see how the baby drives!



It appears that the bearings on my car had been changed out or greased sometime recently as the grease is super clean and blue in color.

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[MB968]

When I installed the missing washer behind the clamping nut on my car today, I found that the fit of the washer on the spindle was quite loose (ID of washer a lot bigger than the OD of the spindle, I'd guess by about 1/16" as shown in the pic). So, as it turned out, following step 3 of the procedure from the <acronym title='factory service manual'>FSM</acronym> was no problem. After tightening the nut in previous steps so the washer couldn't be moved, Step 3 states "Loosen clamping nut far enough to allow the thrust washer to be shifted barely with a screwdriver." It was easy to see it move when I pushed it back an forth with the screwdriver, due to the large gap between the washer and spindle.

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[flash]

more grease!

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