Truck in question: 2000 GMC Sierra 1500 ECSB 4x4 Z71


I just put new american racing wheels and bridgestone tires on my truck (I previously had 20" rims w/33" tires on). I noticed a light vibration/shake in the steering wheel at all speeds, but gets worse as speed increases.

Here is what I did so far to diagnose the problem:

1. Had the tire dealer balance and re-balance the tires. They balanced out nice with 1.0 weights or less, so that's not the problem.

2. Had the tire dealer remove the tires from the rims. Put the rims on the high speed balancer and checked for roundness, staightness, and if they were on center. All checked out OK.
Had the tires re-installed, re-balanced and put on the high speed balancer for the same checks as the rims. All checked out OK.
So, it's not the rims and/or tires.

3. Jacked the front end up by the control arms (one side at a time). Checked for play in the ball joints. Ball joints are tight and greased--not the problem.

4. Pulled the front wheels off. Checked wheel surface mounting areas (brake disc and rim hub)and all were clean/smooth---not the problem.
I also checked the lug nuts and the rims lug nut seats for fitment, and all checked out OK--not the problem.

5. Checked the rotors and found that the front passenger side rotor is Very, Very, slightly warped/bent. The front driver side rotor is dead straight.

Could it be the passenger side rotor causing the problem?
Or could it be something in the steering assembly?
Or could it be the bearings in the axle/hub assembly?
Shocks are new, torsion bars original, any possibilities with them?

Thanks,
Dave

 

any ideas?

 

it could be the passenger side rotor, if that's the only thing that looks to be out of whack. I think I've heard somewhere that warped rotor will have that effect, but I'm no expert.

 

The rotor shouldn't give you a vibration unless the brakes are applied. Maybe you're experiencing a driveline vibration, from the driveshaft or a u-joint. A driveshaft that is out of balance will cause vibrations that increase with speed.

 

buddyhayes is right...rotors cause shakin when brakes are applied...you did say the tires are round, right?

 

Tires are round. Rims are good.

Steering assembly a possibility?

 

Are you talking the front or rear drive shaft, or both?

How do you check the driveshafts? How do you have them balanced?

Is it possible that they came out of balance? -- They are original factory equip.

=Dave

 

Just call around if your not under warranty. I was thinking driveshaft or carrier bearing also. When is the last time you changed the shocks?

 

Front and rear shocks are 3 months old.

What is / where is the carrier bearing?

=Dave

 

Not sure if the 4x4 even has one since the transfer case is there. But it's the peice that connects the 2 piece drive shaft in the middle. Did you notice anything else with the new shocks?