greg928GTS

I recently got my liftbars and I'd like to check for any wheel bearing issues, front and rear, and I need some guidance on how to check them.

I'm getting a vibration at highway speeds that doesn't appear to be a tire balancing issue.

BC

Well, with the wheel off the ground, at least at the front, the only thing keeping it from tilting and banging around as it turns is the wheel bearing. The inner and the outer hold the hub in control on the spindle shaft. That hub is then bolted to the wheel. So essentially its just the threaded collar that clamps the last shaped washer down against the wheel bearings that are on the spindle shaft that is shaped like a slender cone.

At 47k miles they may not be....worn, but they may need adjusting, and that is done at that colar behind the grease cap.


This above is only for the front. The rear is a different story entirely. It involves big bolts with 400lb foot release pressures, presses, and suspension disassembly.

Nice rub-stripless 928 by the way.

AO

Greg- You'll have to do this one side at a time. Jack up the side, and with the wheels straight, grab the wheel at 12 & 6 and try to wiggle. There should be almost no play at all - if there is, it could be a loose wheel bearing or a bad one. Now try at 3 & 9 - this is where it get tricky as the wheel is designed to move this way. If you you have a steering rack centering bolt, use it, if not get one from 928 spec for about $5 on your next order - otherwise lock the steering column for now. If there is any play, it could be the inner/outer ball joint on the tie rod or the rack or the rack mounts - you'll need to investigate further. Repeat on the other side. HTH!

ZEUS+

Do you feel the vibration in the steering wheel ? Or does it feel like it is in the seat of your pants ? While it is best to check everything, trying to isolate the vibration to front or rear will help for proper diagnosiing.

abbzer0

Replaced the rear wheel bearings on my 928. Another way would be to unbolt and remove your wheels. Remove the rotor, etc.. So you can just move the front of the hub assembly. When you turn it (either way) it should move smoothly, and without any noise. If you hear or feel a slight grinding, your bearings are likely shot, as was the case with mine. My 928 hadn't been driven in quite a while, and when I had the old bearings pressed out, I could see the rust in there.

Here is some information from an old post that I made, it may help save you some money. Either way, best of luck.

OH - And I found the easiest way to get them to the machine shop is to just remove the entire hub carrier. IE: Remove eccentric(sp) bolts, etc.. and just take it with you. It was SOOO worth my while to have the machine shop take care of it, as opposed to doing it myself. Just my $0.02 though.

jon928se

Fronts as has been said are adjustable and can be a little loose without making noise normally then OK to just take up the slack but do not overtighten - that will cause them to fail pretty quickly. Rears seem to make noise before getting loose.

Jack the car up then try and rock the wheel vertically or horizontally if there is movement you can prove it is the bearing and not ball joints by having your assistant press on the brake pedal and repeating the test. If the movement ceases the bearing is loose/worn if the movement is still there and the same it is ball joints/suspension bushings. Having the brakes on locks the hub to the hub carrier eliminating any loose bearing movment. This doesn't apply to pre 86.5 cars with the sliding calipers.

jpitman2

iF YOU DONT HAVE LSD, you can jack up one rear at a time, and run some power into it, try to note noise level, then do the other side, and see if they make same sort of noises. If no obvious sounds of grinding, rumbling etc, and both seem the same, probably ok. If you have lsd, you MUST jack both rears off the ground, and run them, and check for sounds at each wheel.
jp 83 Euro S AT 50k

lorenolson888

yup, grab the wheel... there should be no play....

If it ain't broke don't fix it...

I need to check mine but so far so good... I did them a while back...


https://rennlist.com/forums/showthre...=wheel+bearing

If you feel like getting dirty go for it!!! In a way you are the only person that you can fully trust...

LO

greg928GTS

Thanks for the responses and sorry so late in getting back.

I had the rear bearings replaced just 1000 miles ago when I changed the rear wheel studs to accommodate the slimmer wheel spacers when I installed my new wheels.

After about 500 miles, I started noticing the vibration, and I've had the wheels balanced with the Hunter Road Force system twice without helping the vibration. The vibration is more in the seat of my pants than the wheel. It started happening only at speeds above 100, but recently I'm noticing it at 70. I've noticed the vibration coming and going in rythmic surges of about 4 or 5 second intervals.

Can anyone else second the idea of jacking the rear of the car and putting it in drive to listen for rumbling or other noises? Sounds dangerous to me. We know how those Aussies are!

ZEUS+

Is there any warranty for the rear bearing work ?

greg928GTS

I'm sure the mechanic who did the work would take care of it if that was the problem. I could bring my car back up there to check, but he's 1.5 hours away, and besides, I'd like to start doing some of my own work on my car. I figure checking the wheel bearings is a pretty easy job that I can do.

Now changing the wheel bearings . . . . I'd have to think about that a little.

ZEUS+

Not assuming anything,we know how to spell assume(LOL). From what you describe, it is a rear vibration. It could be a coincidence but it showed up after the rear studs and bearings. I dont recommend spinning the wheels when jacked up. It will also set off the ABS.

worf928

Greg, I'm with Zeus+ on this. If you are feeling the vibration through your butt and not through the wheel then that would seem to implicate the rear wheel bearings. Also, since they were just done Ocham's Razor suggests that they (or something in the vicinity) are the culprit.

Two things:

It is not necessary to remove the rear wheel hubs, as per the WSM, to remove the RWBs. Sir Tools makes a kit that can be used to press-out the old bearing and press-in the new bearing. It works well and takes a lot less time.

The way I isolated my RWB problem was to remove all items from the rear. Carpet, tool kit, spare, etc., so that there was nothing to insulate the noise. I then drove around with CarChick in the back while she crawled around listening for the noise. If the noise is at the outside of the hatch area then its either the RWB or the outer CV joint. If it's towards the middle then it might be the inner joint.

In order to R&R the RWBs it is necessary to disassemble the parking brake assembly. I have to wonder if improper re-assembly of the parking brake could be a culprit here. How is your e-brake? Does it take more 'clicks' to engage? Fewer? Anything different about how it 'feels?'

ZEUS+

I wish you were closer,Benton is about 5-6 hours from here.

greg928GTS

Nice weather this weekend, so I'll get it out on the highway with the Mrs. driving and see if I can hear where the vibration/noise is happening. I'll also do a basic wiggle check of the 4 wheels. That will give me a chance to use my new liftbars, and a good excuse to get a set of jack stands.

So, bad rear wheel bearings just make noise, they don't develop too much play?

Somehow I'm not convinced that I'll be able to isolate the location of the vibration/noise from a driving test, so I just want to have other things I can be looking for.

Thanks Dave and Zeus