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Posted by: SirAndy Aug 11 2009, 11:41 AM

Is there a quick way to check the rear wheel bearings?

Andy

Posted by: Dr. Roger Aug 11 2009, 11:59 AM

don't you just jack up the rear and grab hold of the rear wheels and give them a jiggle?

too much juggle means too much wear.

it's what the PCA uses during tech inspection.

Posted by: mikez Aug 11 2009, 12:04 PM

Do da jiggle....

Posted by: puff adder Aug 11 2009, 12:18 PM

What about regreasing the rear wheel bearings?

On the list of things to do is check and lube EVERYTHING on my race car.

Posted by: underthetire Aug 11 2009, 12:29 PM

Sealed bearings and you pretty much destroy them pulling the hub out.
Spin them to check for noise to.

Posted by: 9146986 Aug 11 2009, 03:37 PM

Jack up the car, do the jiggle as above. You can also pry up on the wheel and see if there's slack.

Posted by: URY914 Aug 11 2009, 03:49 PM

Simple test....

No noise = good
Noise = bad

Posted by: turnaround89 Aug 11 2009, 04:27 PM

wouldn't the bearing cover stop the jiggle?

Posted by: SLITS Aug 11 2009, 05:28 PM

No .....

The stub axle installed does though.

Posted by: charliew Aug 11 2009, 05:32 PM

I wasn't aware the 914 had rear wheel bearings.

Posted by: Eric_Shea Aug 11 2009, 05:55 PM

The "quick" way when I was tech'ing for PCA was to place both hands on or near the top of the tire and rock the car back and forth. Listen for a click or clunk. You can always find a bad or loose bearing front or rear that way. No need to jack anything.

Posted by: r_towle Aug 11 2009, 06:01 PM

remove the bearing....it will be bad then.

Rich

Posted by: davep Aug 11 2009, 06:02 PM

If you don't have bearings, the wheels don't rotate.
The 914 has a double row ball bearing.

Posted by: charliew Aug 11 2009, 06:07 PM

The 914 has a double row rear HUB/AXLE bearing. The only wheel bearings I know of are on the front of rear drive cars.

Posted by: URY914 Aug 11 2009, 06:37 PM

Bad bearing race:


Attached thumbnail(s)

Posted by: type2man Aug 11 2009, 07:17 PM

A good way to test the bearings is to speed up to about 50 mph and shut the engine off and coast(DONT TURN THE KEY TO WHERE IT LOCKS THE COLUMN!!!). Rock the steering wheel from side to side slowly. Bad bearings will give you a roar or a hum when a side load is a applied.

Posted by: SirAndy Aug 12 2009, 12:27 AM

Wouldn't the rear one piece bearing have to be completely shot to give you a "clunk"?
For the front, the jiggle makes sense as there's not much support for the two piece bearing.

In the rear, with everything assembled, one would think that a worn bearing would still sit pretty tight on the large surface.

Also, there's so much noise from the calipers and axles when turning the wheel by hand, you can't really tell unless your bearing was already in a million pieces.


Am i just doing this wrong? I'm getting some weird grinding noises from the rear when driving, but neither the jiggle nor listening while turning the wheel by hand produce any obvious results.

Andy

Posted by: charliew Aug 13 2009, 12:12 AM

Have you tried putting it in neutral and coasting to see if it's in the tranny? Or as Typ2 man suggested turning in circles in neutral to see if it changes the sound?

Posted by: SirAndy Aug 13 2009, 11:41 AM

Yes.

You can clearly hear a grinding noise from the rear. Metal to metal. Depending on how you load/unload the suspension. Even at very low speeds (think getting into the driveway at an angle) ...

I thought it might be my brake rotors hitting the calipers, but turning down the rotors didn't make a difference. And there are no wear marks on the calipers.

The sound goes with the revolution of the wheels, not the motor ... (clutch in/out makes no difference) ...

What else could it be besides the wheel bearings?
Andy

Posted by: jcd914 Aug 13 2009, 01:08 PM

Do you have a limited slip diff?
Porsche LSD without the proper gear oil or additive can be noisy. When you turn to load the suspension one side or the other you also force the diff to work.

That said, your description does sound like wheel bearings to me and I suspect you put some hefty side loads on the rear suspension.
If you can put it up on a rack and run it in gear and listen with a stethoscope you will probably find 1 side louder that the other. This takes at least 2 people, 1 in the driver seat a 2nd to listen, if you have a 3rd to watch for safety hazards, could save you from lifting you head into a hot header or such. Of course up on a lift changes the load on the bearings and they maybe quiet the. You will also get a lot of other noise and vibration so it can be a challenge to sort out. Spin up the wheels and then put in neutral and shut off the engine and listen as the wheels coast down.
I know this does not count as an easy method and it does not even work all the time but it is something you can do short of replacing both rear bearings.

Good Luck
Jim

Posted by: yeahmag Aug 13 2009, 01:49 PM

Andy,

Have you ever changed out the rear bearings? If not it's probably a good idea. I managed it myself with little drama... Freezing the bearing and heating the trailing arm is key to getting them in easy.

Posted by: Phoenix 914-6GT Aug 13 2009, 01:56 PM

Or just use a bearing pulling and make it even easier

They should just pull right in. Then when you tighten the stub axle everything really tightens.

Posted by: SirAndy Aug 13 2009, 02:05 PM

No LSD.

We installed new bearings at the same time the 3.6L motor went in.

I trust McMark knows how to install a wheel bearing.
Andy

Posted by: McMark Aug 13 2009, 03:25 PM

I suppose it could be a defective bearing?

Posted by: yeahmag Aug 13 2009, 04:00 PM

I second the running it on a lift. I thought I had a bad bearing and it was a bad trans!

Posted by: Nozzle Aug 13 2009, 07:28 PM

I had my rear bearings pass the wiggle test on a lift with no problem at a tech inspection but I kept hearing some noise coming out of the left rear in turns. So I took the rotor off, turned the hubs by hand and it felt like the left bearing was full of gravel and sand. Changed them both out with a new bearings and all is right with the world.

Posted by: r_towle Aug 13 2009, 07:30 PM

There is an idea
remove wheel, rotor, caliper and axle.
Then turn it.

Rich

Posted by: SirAndy Aug 13 2009, 07:36 PM

And that's "the quick way" ???
Andy

Posted by: r_towle Aug 13 2009, 07:42 PM

funny....I KNEW you would say that...

Seems like the fastest way to be sure.
I was thinking....

you could probably remove the inner axle and spin it by hand with the axle attached...
that would be easier.
Rich

Posted by: DBCooper Aug 14 2009, 08:02 AM

You'll probably only need to remove the caliper. Noise loud enough to hear when driving that's coming from anything else will probably require attention anyway, and if it's on a lift it should be pretty easy to tell where it's coming from.

Five minutes, quick enough?