Wheel Bearings/Hub Assembly Help

Problem: Vibrating and humming coming from front end, directly related to wheel speed...at all speeds....believed to be wheel bearings.

Done so far: Replaced passenger front hub/bearing set

***Vibrating is still there, and now CV joint on that side is clunking, too. Double checked all bolts on hub, caliper bracket and caliper, and axle nut (tightened w/ electric impact gun)...all tight. WHY IS IT CLUNKING NOW?

***Plan on changing driver's side hub/bearing set, but one of the three 13mm bolts that hold hub on is rounded off...I am going to try to get it off tonight with gator grip or metrix, but I need new bolts. WHAT ARE SPECS OF HUB BOLT SO I CAN BUY NEW ONES?

ANY OTHER ADVICE??

Welcome to AF.

Your first mistake was tightening it with an impact. The hammering action of the impact can and will damage both the axle shaft and hub bearing. Second, you have to torque the axle nut to a specific torque value. The torque pre-loads the bearing to hold it together. They are only press fit in the box, the torque is what keeps them together. Failure to do so will allow the bearing to separate (if too loose) or hum (if too tight) and either clunk or pop as the wheel is turned. Make sure you follow the torque spec that comes with the bearing if it differs from a manual, as design changes can necessitate a new torque spec.

Also, what brand bearing did you buy? NEVER, EVER buy the cheapo, white box generic Chinese bearings for any car that has an ABS sensor in it, as they are JUNK!

Here's a link to the install proceedure from our tips and maintenance sub-forum: http://www.automotiveforums.com/vbulletin/showthread.php?t=665622

Thanks for reply...

I WISH I HAD THE INSTRUCTIONS FROM HERE BEFORE I STARTED!!!!!!!!

I did buy cheapo white box hub assembly. How can I tell if I damaged the hub/bearing assembly? Is there any way of determining if a bearing set is bad? If its clunking now, did I for sure damage the axle shaft or hub/bearing assembly, or is it just too tight/loose? Is there any way to tell?

The problem I had yesterday was that I was not sure which side was bad. My mechanic buddy said it was passenger side. I replaced that one (incorrectly, I might add), and the car is still humming/vibrating. Should I try to replace the other side, too? Are bearings like brakes, and you should replace them both at the same time?

How do I fix the car and my mistakes?

Thanks.

do you still have the old bearing from the passenger side? Since I have done a ton of these bearings, I am quite fast at it, so i myself would put the one that came off the passenger side on the drivers side. Just to see if it corrects the problem. The berarings have the same part number for both sides.

Then i would loosen the axel nut (this can be don without jacking up the wheel) and retorque it to the correct spec.

Thanks for the info.


Yeah, I have the original set from pass. side. I was hesitant to install it on driver's side, but will try it. Are you saying that if I torque the new one on pass. side to correct spec the clunking will go away?

Thanks...

Also, anybody (richtazz) able to answer my other questions from previous post?

Thanks again...

Im saying that if you retorque it and the noise does go away you got lucky. Also swapping would tell if maybe its a possable problem with the otherside instead.

The bolts that hold the hub to the spindle are a special bolt due to the small head size, so they may be difficult to find at a local hardware or bolt place. To answer your question, they are M12x1.5x40mm with a 13mm integral washered head and a 10.9 hardness.

First off, I am very appreciative of the help thus far. Thanks guys for humoring my demands.

Another question...The new clunking sound, is it just an annoying noise or do I have another self-created problem to deal with?

the local GM garage has two of those bolts on stock for $6.07/ea. I am buying them both at lunch today.

Also, previously asked:

1. How can I tell if I damaged the hub/bearing assembly?

2. Is there any way of determining if a bearing set is bad?

3. If its clunking now, did I for sure damage the axle shaft or hub/bearing assembly, or is it just too tight/loose? Is there any way to tell?

I am obviously marching on uncharted territory in my experience in vehicle maintenance. I am asking all of these questions because you fellas have more knowledge and experience than me. I am not trying to be pesty or pushy.

1. How can I tell if I damaged the hub/bearing assembly?

2. Is there any way of determining if a bearing set is bad?

There is really no way to determine if you damaged the new hub, other than to loosen and re-torque the axle nut to proper torque spec and see if the noises go away.

To determine if an old hub is bad, jack the car up and grab the wheel at multiple positions (3-9 o'clock, 10-2, 12-6 etc...). If it moves at all positions, the hub is definitely bad. Normally, when driving, the hub on the unloaded side (drivers side while making a left turn, pass side if making a right turn) will get louder as you make a gradual turn.

Can I jump in with a question? I never knew that using an impact wrench on that axle nut was a bad thing to do. I've always loosened it with the car not jacked up, so the wheel doesn't move. So are you saying it should only be done by hand?

I believe they are referring to the tightening the axle nut and over-tightening it. I can't see a problem removing it with an impact wrench.

Can I jump in with a question? I never knew that using an impact wrench on that axle nut was a bad thing to do. I've always loosened it with the car not jacked up, so the wheel doesn't move. So are you saying it should only be done by hand?
The easiest way to loss the axle nut is after the car is jacked up & wheel/tire removed. Just jam a large screwdriver thru the brake caliper into the rotor vent. With a 1/2"-socket breaker bar of 18" or longer, the nut will come off with little effort. Adding a 2'-3' metal pipe to the breaker bar if you have to.

I am a small guy and I replaced both wheel bearing with just my 18" breaker bar. I see no reason why anyone resolve to more powerful tool. Doing it by hand with 6-pt socket and longest breaker bar that fits inside wheel well, I don't risk stripping the nuts. Also, keep in mind that GM nuts are mostly metric; alway use the correct size sockets.

For future reference to remove the 3 wheel bearing bolts, use a 13MM 6-pt 1/2"-drive socket+1",3", or 5" extension+18" breaker bar. To access easily to the top bolt, just tilt wheel slightly or use wobble-style extension.

Using an impact wrench on an ABS equipped hub bearing, whether to loosen or tighten is a bad idea. The hammering action of the impact can damage the fragile ABS sensor components, or impart small grooves in the bearing race surface, causing accelerated wear and a minute vibration that will gradually get worse and destroy the bearing. This hammering action can do the same thing to the internals of the CV axle's joints, causing problems there too. My best suggestion is to stay away from your impact wrench when working with hub bearings and CV axles.

Well, its all fixed. I used the advice you guys gave me here in this thread. I put the old hub back in the passenger side, and replaced the driver's side with a new set, not the cheap ones either. To sum things up, I will NEVER use any impact tools on those parts. I was able to loosen and tighten the axle nut with a ratchet and a short scrap of conduit I had laying around, then torqued to spec with a rented torque wrench. No clunking, no clicking, no vibrating. All smooth. Thanks for the advice.

Good Job!!!!

Thanks...

I can't say I am a master quite yet, but the last time I started the process by jacking up the car, I was letting down the jack for a test drive less than 1/2 hour later.

While holdng the bad (driver's side) hub/bearing set in my hands and spinning it, there was a noticeable difference in the tension, smoothness, and sound it made in comparison to the new one, and the old one that was still good on the other side. I could tell it was shot from there.

I'll definitely be checking around here before making any more repairs to my rides. :banghead: