Have you checked the front wheel bearings? Jack the truck up so the tire is off the ground, grab the tire at the 12 and 6 o'clock position and rock back and forth. If there is any play, it's the bearing.

 

Yea, sorry, I forgot to mention that I did do that check. No play whatsoever.

 

I'd try rotating wheels front to back and see if the vibration changes at all. And it's hard to tell without actually seeing your wheels on the balancer, but if your tires are "out of round" (belt shift or bubble) they may be able to balance but still cause a vibration. This happened when I had my cooper discoverer STT's, I got them to balance on the balancer but had some vibration up until I got some new tires.

Also, this can be dangerous, but try jacking the truck up (safest on a lift but not all of us have that luxury) with the rear wheels off the ground and have a buddy run the truck at the speed where the vibration occurs. You may be able to at least pinpoint the area more.

Lastly, pull the drive shaft and check the U-Joints. If they feel "rough" when you move them, then I would replace the u joints.

 

I'd try rotating wheels front to back and see if the vibration changes at all. And it's hard to tell without actually seeing your wheels on the balancer, but if your tires are "out of round" (belt shift or bubble) they may be able to balance but still cause a vibration. This happened when I had my cooper discoverer STT's, I got them to balance on the balancer but had some vibration up until I got some new tires.

Also, this can be dangerous, but try jacking the truck up (safest on a lift but not all of us have that luxury) with the rear wheels off the ground and have a buddy run the truck at the speed where the vibration occurs. You may be able to at least pinpoint the area more.

Lastly, pull the drive shaft and check the U-Joints. If they feel "rough" when you move them, then I would replace the u joints.

Thanks, jliska50. I'll look in to the "out of round" possibility and the ujoints.

 

It feels like it is coming more from the passenger side. Would the fact that my jounce bumper on my passenger side is slightly touching my LCA cause a vibration like this?

With 265 size tires at 55 psi, using a yard stick w/ a built in level, from the ground through the center of my wheel to the fender is 39” on the driver side and 39.25” on the passenger side.

Jounce bumpers: drivers side is 0.25 inches off the lower control arm, passenger side is slightly touching the lower control arm. (I replaced the originals which were trashed with the yellow pointed Z71 poly ones.)

Upper control arm: I appear to have plenty of clearance between the UCA and the frame stop.

 

Take your driveshaft to a pro. He will straighten, balance and install new joints.

 

I tried to edit last post.


Because it is free, reduce your air pressure to 45 psi all the way around and see if this helps. Certain tires can vibrate when over inflated.

 

I haven't been able to get to a driveline shop yet so unbalanced drive shafts and/or u joints could still be the issue. In the meantime, am still trying to diagnose.

I jacked up the front passenger side wheel using the LCA tonight and tested side to side (hands at 9 and 3) movement of the wheel. Got a good bit of movement in the tie rod and center link.

Could this be the source of the vibration?

 

It most definitely could. It will let the front wheel wander with the road and could cause a vibration feeling. Be sure to check all the components and have an alignment done after they are replaced. You should also take the opportunity to tighten the torsions prior to the alignment if you think they are saggin a little.

 

Closing the loop on this one. It was crappy balancing and bad alignment (from the dealer) and bad tires. Even though the Michelin X-Radials were only 25% to 50% gone, the tire shop I went to were only able to get one barely within balancing spec. Didn't fix it (like they said might happen) so I opted to get two new Michelin LTX M/S2's on the front (already had 2 one week old ones on the back) and voila, problem solved.

 

Closing the loop on this one. It was crappy balancing and bad alignment (from the dealer) and bad tires. Even though the Michelin X-Radials were only 25% to 50% gone, the tire shop I went to were only able to get one barely within balancing spec. Didn't fix it (like they said might happen) so I opted to get two new Michelin LTX M/S2's on the front (already had 2 one week old ones on the back) and voila, problem solved.

Yup it sure makes troubleshooting frustrating when a tire shop does a bad balance or an alignment shop does a bad alignment. You try to cross these items off your list and dig in deeper but it turns out to be something simple you already did once.

 

Good to know you finally got it, vibrations are the worst.

 

HotButteredLBZ,

I am glad to read that your vehicle was repaired and you are experiencing no issues since then. Just know that GM Customer Care is here on the forum if you ever have any general questions or concerns about GM products.

Safe travels,

Jennifer T.
GM Customer Care

 

Thanks, Jennifer. I appreciate you taking an interest in my problem.

 

It is my experience that it usually isnt the mechanic, but the shop that is the problem.