Bad Bearing?

cmcfaul · cmcfaul's Garage

How do you tell if a rear wheel bearing is bad?

My car is making a constant noise from the rear when coasting. I replaced the rear bearings and cv joints about 4 years ago. CV's still look good, no tears in the boots or loose screws. It dose not matter if I have the clutch in or out.

There is play in the left wheel if I pull on it when it is off the ground. It moves ever so slightly (top of wheel moves a couple mm but I hear it and feel it more than see it. the wheel rotates freely with no unusual noise when turned by hand. Is this a bad bearing?

It's no small feat changing these so I want to make sure I am doing the right thing. Especially since it has not been very long since I last did it.

I tried to tighten the castle nut but it's on there about as tight as I dare try to turn it.

Thanks,

Chris

73 911 E

CCM911 · 01-26-2010, 09:11 AM

When you turn side to side at speed, does the noise stop, and then start again when you straighten out?

Jim Richards · 01-26-2010, 09:12 AM

Hey Chris, is it possible that you have a dragging brake pad or debris between the pad and rotor? Or how about the emergency brakes? Are they adjusted properly?

cmcfaul · cmcfaul's Garage

I think everything around the brakes is to spec. The wheels spins freely when off the ground. there is no apparent drag when driving around town.

Chris

IROC · IROC's Garage

Quote:

Originally Posted by CCM911

When you turn side to side at speed, does the noise stop, and then start again when you straighten out?

+1. To me, this is the best indication of rear wheel bearing wear - a noticeable difference in the tone of the "growl" when making a sweeping right or left turn. In fact, when going in a straight line, my wheel bearings were essentially quiet, but when turning right a very noticeable growling could be heard.

I had no play at all in the wheel, but replacing the bearing made the growl go away...

kodioneill · kodioneill's Garage

If you can rock the wheel that amount by pulling on the top, your wheel bearing is bad. You should not be able to move it at all.

Superman · 01-26-2010, 12:22 PM

Constant noise suggests wheel bearing. Wheel bearing noise is almost always a "growl" noise. I do not believe there should be ANY lateral play. The wheel should turn in its usual rotational direction, but no part of the wheel should move in a direction 90-degrees from that. Not on the rear, anyway. Any play in that rear bearing is too much.

Superman · 01-26-2010, 12:24 PM

One more thing. As you probably know, there is a tool that allows the rear bearing to be chanced without removing the banana arm and taking it to a machine shop, then realigning the car when finished. The tool sidesteps all that. And finally, often times when a fairly fresh rear bearing becomes bad, the BIG nut is not tight enough. It is hard to get that nut too tight. Easy to get it not tight enough.

CCM911 · 01-26-2010, 12:52 PM

Superman is correct. There is a tool that allows you to replace a bearing while still on the car. We just did mine, and it was really easy. I didn't even have to take apart the emergency brakes! Just remember to freeze the bearings before install, and heat up the carrier. The bearing will then slip right in. And now my car is so quiet.

rusnak · 01-26-2010, 01:36 PM

Chris,

It's easier to check w the car on the ground. Push the bumper sideways with your shin, and look at the rear wheel. If it moves side to side, then the bearing is bad. You'll also notice the car darting all over the place when you drive down the road.

If you're close by, I'll bring my bearing puller over. It's a quick way to change the bearing without a hydraulic press.

daleski · 02-21-2010, 05:09 PM

What tool do I need to change the bearing while still on the car?

1980 911SC

Walt Fricke · 02-21-2010, 05:19 PM

Chris - before you get too deeply into this, tighten the nut which holds all this together at the rear. All are correct in saying that there should be zero play in the rear bearings. But it is just possible that you didn't get things entirely seated when replacing the bearings, and that you can get rid of the play. You will recall how much torque was needed here. See if you can get at least one slot's worth of castellated nut turn.

If you can get rid of the play, then drive it and see if the noise is gone (or is less). It might or might not be, but this is worth the try before getting too deeply into this. 4 years is a pretty short time for a bearing to go bad..

Walt

2.70Racer · 02-21-2010, 08:49 PM

I too had noise from the rear a couple months ago after returning from a 2000 mile round trip.
My '85 911 has 180,000 miles so I installed new rear wheel bearings and new CV joints.
By the way even with the proper wheel bearing tool, this job is tough.
So much to my surprise the noise was still coming from the rear.
After all that work my problem wasn't solved.
While visiting a friend with a mile long dirt driveway, I noticed what seemed to be no noise.
I put on an old set of rear wheels and tires. Went on a test drive and no noise!
My BF Goodrich G-Force tires with about 15,000 miles were the source of the noise.
Great tires until they wore down to 5/32's. I could not believe these tires were the problem.
Well now, nice new tight CV Joints, Bearings and new rear tires. I'm set for the next 40,000 miles.