weird vibration

[twinners]

3 times now in 4 days we have had a weird vibration from our 08 tb. The 1st was my wife braking to stop for a red light. She thought was like when you hit the rumble strips on the side of the highway. She said as soon as she started driving after being stopped it went away. The next dayy I had just pulled into a parking lot when I noticed it. As I slowed down to park it lessened and then stopped when I was stopped. Took a look and could not find anything rubbing on the tire. I thought maybe a stuck brake as I had to stop quickly just before but I did not notice it pulling to one side. Today as I am driving about 40 mph I notice it again. Pull over and again can't find anything. When I get home I put it in 4hi and it drives fine straight but when I turned sharp the back wheel almost spun trying to push through the corner. Same thing turning left and right. No turning problems in 2 hi. Truck has 62000 miles. Changed front and rear diff and tc fluid a month ago. Only had the truck for about about 4 months. Plan on checking fluid levels tomorrow but looking for other help. Thanks in advance.

 

[The_Roadie]

That behavior in 4HI is expected. Called driveline binding. A couple of ideas to try - turn off Stabilitrac, and check your ebrake functionality. Sometimes the ABS system activates when it shouldn't due to flaky wiring to the RPM sensors in the wheel hubs or rear axle. Pull the ABS fuse to totally disable the system for a check.

 

[twinners]

Thanks for the ideas. How should I check the ebrake? Set it and try to drive or apply it while driving?

 

[Metsämies]

It may aslo be a warped brake rotor, or a loose brake caliper.

 

[The_Roadie]

How should I check the ebrake?

Everybody should test their ebrake every week or so by applying it while driving slowly and see if it's effective at all in slowing you down. There's a debate whether it should be called a parking brake because that's all the GM lawyers advise you use it for, but in my opinion, if it doesn't have ANY ability to stop you in some distance from any speed, you might as well not trust it for parking either.

In some cases, the friction material comes off the brake shoes and turns into a noisemaker and some owners don't even know there's a mini-drum brake built into the rear rotor hubs.

 

[twinners]

Checked the brake on the way home from dropping the kiddos off at school. Works fine, which I shoulg have known because I set it if I park on the driveway. Going to check front diff and tc fluids before I go anywhere else. Kind of wish I didn't have the running boards on now but such is life. When pulling the abs fuse it would only tell me that is the issue if it does not happen again, is that correct. Is it a problem to drive for a couple days without that fuse in? Thanks for the replies.

 

[twinners]

Fluid levels in front diff and tc look good. Pulled the ABS fuse to see if it happens again. Also noticed there is at least one fuse in the block that is not in the diagram in the manual. Seems kind of odd. Might drop be les schwab to have them take a look at the brakes and see if something is loose.

 

[The_Roadie]

Also noticed there is at least one fuse in the block that is not in the diagram in the manual. Seems kind of odd.

Details or a pic?

You can safety (except for the odd panic stop) run without ABS. It's not like losing power steering or brakes.

 

[twinners]

It is fuse #64. It is shown on the inside of the fuse block cover but it is not shown in my manual. Les Schwab said everything looked good concerning brakes. While driving today with the ABS fuse pulled it did do the vibration for just a second then stopped when I put the brakes on to slow down for a light. Guess that rules out the ABS. Something in the hub maybe?

 

[gmcman]

When you tap the brakes, does the steering wheel turn briefly to one side? Is the vibration at a steady 40 MPH or is it only felt when braking?

Did any of the wheels throw a wheel weight?

Does the vibration get worse at higher speeds?

 

[twinners]

I have not noticed the steering wheel pulling at all with the brakes applied. It will happen at different speeds from stopping for a light to coasting in a parking lot to driving down the road on the gas. When it happens it is related to how fast I am going. As I stopped it slowed down as the tires did. Kind of reminded me of running over a pop can with a bicycle and leaving it on your tire. As the bike slowed down the sound and vibration get lower and quieter.

 

[gmcman]

Did this happen all of a sudden or slowly over time the reason I ask is it could be your front bearings. They tend to sound like you have a set of mud tires on when they are excessively worn

 

[jeffro312]

I'll confirm GMC man just replaced my wheel hubs. It was more of a droning noise went with speed louder in turns. Didn't really notice a feel until I drove with the new ones

 

[twinners]

If it was a bearing would it come and go? It did not happen at all today and it seems to stop after stepping on the brakes or stopping completely. It has to be something in the wheels or driveline but it sure is frustrating.

 

[jeffro312]

If it was a bearing would it come and go? It did not happen at all today and it seems to stop after stepping on the brakes or stopping completely. It has to be something in the wheels or driveline but it sure is frustrating.

So are you feeling a vibration that goes away or do you hear something

 

[gmcman]

If it was a bearing would it come and go? It did not happen at all today and it seems to stop after stepping on the brakes or stopping completely. It has to be something in the wheels or driveline but it sure is frustrating.

When you say it stops after applying the brakes is this just a gentle tap on the brakes and the noise stops?

When you say the noise stops after coming to a stop does it go away the moment when you let off the gas or just stop moving?

When I get home I put it in 4hi and it drives fine straight but when I turned sharp the back wheel almost spun trying to push through the corner. Same thing turning left and right. No turning problems in 2 hi.

Like Roadie stated this is driveline binding (normal) and is not recommended on dry pavement, especially tight turns.

In some cases, the friction material comes off the brake shoes and turns into a noisemaker and some owners don't even know there's a mini-drum brake built into the rear rotor hubs.

That's some great advice there, pain to check but determining you don't have anything between the pad and the rotor narrows down your search.


Did you replace the TC fluid with the GM Auto-Trac Fluid?

Are your lug nuts tight?

Does the brake pedal feel harder than normal to apply? Not a likely scenario but when the diaphragm in the brake booster ruptures it makes odd vibrating sounds sometimes. This is likely not the case but a thought.

Does this happen with the A/C on? If so try turning it off when the noise starts.

I wonder if the front splined disconnect is not fully disengaging.

 

[gmcman]

If it was a bearing would it come and go? It did not happen at all today and it seems to stop after stepping on the brakes or stopping completely. It has to be something in the wheels or driveline but it sure is frustrating.

When I mentioned earlier about being excessively worn, I meant way beyond droning noise to near all out failure. IF they are this worn you MIGHT be able to raise the front wheel (by the lower control arm, not the frame) this will allow unloading of the axle shaft.....and grab the tire at 12 & 6 and try to rock back and forth. They generally have no movement when beginning the droning phase.

If you have noticeable movement, not suspension but an obvious faulty bearing, then that's likely the cause. The fact you have only 62K miles they should still be good unless one smacked a curb.

 

[twinners]

So it's Sunday night and I still have not had the noise/vibration since Wednesday. To answer a few questions yes I used auto trac II. I have not had the a/c running. The two times it happened to me I pulled over and stopped completely to try to see if I couls see anything. I think I said somewhere that when it first happened my thought was I had something jammed against the driver side front tire that was causing both a noise and the vibration.
I don't know if they tried to move the tire like recommended above at Les Schwab but I am going to try it tomorrow. I guess I like the fact that it has not happened again but I am going to be paranoid about it for a long time if I can't figure it out.

 

[twinners]

It's been a bit since I have been on. My computer crashed and it sucks. After going several days with no noise it happened twice in the matter of five minutes. A couple times it has seemed to start after hitting a pothole. And coming to a complete stop is what makes it stop. As soon as I start driving again it is gone. Still need to try to wiggle the tire and see if there is movement.

 

[PJW318]

You ever figure this out? I am having what sounds like same thing happen to mine. Seems to only happen when hitting a bump in road and lasts a few seconds and stops.

 

[twinners]

I have not figured anything out for sure yet. I agree it seems to start sometimes with hitting a bump. I am leaning towards a bearing that maybe gets kind of bound up and the noise is it being forced to turn. Maybe coming to a stop let's it get straightened out? It has been a few days agin since it happened.

 

[LikeEnvoy]

hmm. could this be related to my issue? see http://gmtnation.com/forums/threads...ront-for-few-seconds-when-hitting-bump.17126/

 

[LikeEnvoy]

My issue is solved - it was the "4WD disconnect/intermediate shaft bearing". The needle bearing had broken apart and had damaged the CV axle shaft surface too. So any major bump allowed the CV shaft to oscillate eccentrically in the broken bearing, causing that awful noise.