Noisy ... wheel bearings?

[Fred Munro]

Hi Dave;

Nope, I didn't propose the overtorque idea. It sounds from your description
like wheel bearing noise. These are massive double ball wheel bearings with
a split inner race.The bolt holds the two inner bearing races together and
secures them to the CV joint. Increasing bolt torque would increase the
compression on the inner races, and may bring the races closer together,
reducing internal clearances if there was something (dirt, grease, paint?)
in between the races. Factory spec torque should be enough to do the job. If
overtorquing the bolt quiets the bearing, you may have a damaged bearing or
dirt between the inner races.
I'd suggest replacing the bearings on both sides, since it is often
difficult to tell which bearing is bad (I've replaced good bearings before
:o). Installation technique is critical with these bearings. You must never,
never, press on an unsupported race. If you don't get the assembly order
right, you will ruin the bearing. I generally support the suspension
component on the press bed and press the bearing into the suspension
component pressing on the OUTER race, then support the hub on the press bed,
flip over the suspension piece, and press the bearing onto the hub pressing
on the INNER race.
Since you have overtorqued the axle bolts, you should replace them with new
ones.

HTH

Fred Munro
'94 S4

----- Original Message -----
From: "David Conner" <conner at cfm.Ohio-State.edu>
To: <quattro at audifans.com>
Cc: <munrof at sympatico.ca>
Sent: Saturday, June 23, 2001 11:43 PM
Subject: Noisy ... wheel bearings?


> Fred,
> I have a problem that seems like it could be wheel bearing noise, on an 89
> 100 fwd w/130k miles on it.
> The reason I'm writing to you is because I think you wrote of curing a
> problem like this by tightening the axle bolts/nuts beyond the factory
spec.
>
> A little background ... I rebuilt the front end of this car, so everything
> was apart .... replaced subframe bushings, struts, control arm bushings,
> new CV boots, etc., but not wheel bearings.  Axle nuts were torqued to
spec
> of about 200 ft lbs.
>
> Afterward I was hearing noise that seemed like it was from the left
> (driver) side front wheel.  It wasn't real bad, but annoying mostly on
> gradual curves to the right, especially like a freeway exit.  The noise is
> a low pitched grinding sort of sound that varies with the speed of wheel
> rotation I checked everyhting out and decided it was the wheel bearing.
> Replaced the wheel bearing (SKF) myself and ruined it so then I really had
> noise.  Very carefully replaced the wheel bearing a second time (SKF), and
> I'm pretty sure I did it right, but the original noise was still there.
> This all started last year so I've had lots of time to rule out various
> possibilities.
>
>  I'm sure it's not tires because I've had three different sets of
> wheels/tires on the car and the noise remains with all of them.
>
> I thought it might be related to the brakes... I had all four rotors
turned
> and the noise remained.
>
> Several weeks ago I replaced the front rotors with new ATE, new pads, and
> took apart the front calipers, cleaned and replaced the seals, lubed guide
> pins, etc.  At first the noise was gone and I thought "Aha!  It was a
> damaged (bent?) brake rotor!", but within a week or so the noise crept
back
> to it's old level.  Then over the next few weeks it got worse, got louder
> and began to emanate from both sides.
>
> Today I began anew to search for an answer.  First I inspected everything
> on the front suspension and wheels ... everything looks OK, no abnormal
> play anywhere.  Then I remembered someone (Fred Munro?) on the Q-list once
> wrote their wheel bearings were noisy unless they tightened the axle bolts
> way beyond the factory spec.  So I started playing with the two foot
> breaker bar.  The fwd cars use axle nuts instead of the bolts found on
many
> of the Q's.  Torque spec on the nut is 207 ft lbs.  I tightened both sides
> to about 300 ft lbs and the right side noise went away, and the left side
> noise decreased.  I tightened the left side further, to about 350 - 400.
> Maybe the noise decreased slightly, but it's still there.  Bottom line is
> it looks like I got rid of most of the noise with the increased torque,
but
> not all of it.  I still get a little left side noise on right turns.
> So now what?
> I'm considering replacing the wheel bearing a third time.
> I wonder if the axle nut can be so tight it would damage something?
> The right side wheel bearing is still the original, btw.
>
> Does anybody know how I can get rid of this noise?
>  It's my wife's car and she expects it to be perfect. Any help will be
> appreciated.
> Dave C.
>