Vibration/wobble?

[chucksnee]

Hello all, this maybe a little long, but I have done a lot to get rid of this vibration/wobble...I'll try to provide as much info as possible, this all started with new tires.

 

I have a 2007 GMC Sierra, 4 door, short bed (6ft) with 4.8L.

 

About 1.5 months ago I bought 4 new tires (Michelin LTX MS2 LT 245-70-17) I could not get rid of a vibration after numerous balances at Sears, I finally told them to get me a new set of tire, I got the same type except I went with the "P" series and not the LT series. That helped the vibration/wobble out a lot, but it's still there.

 

I took the truck to Firestone, and they did their undercarriage inspections, removed the tires (checking brakes), they stated the calipers were working as needed, checked to make sure all tie rod ends were ok, they are, there was slight play in the lower ball joints, other than that the only other thing they could find was the clips the brake shoes clip into were rusted, they removed most of the rust and put lube on the contact points and believe it or not that took a lot of the vibration/wobble out. But after a few days of driving it became worse again.

 

So, I bought new brakes and new clips and plenty of lube, that really took out most if not all the vibration, but again after a few days the vibratoin came back, but not nearly as bad.

 

So, my question is, is it possible for the master cylinder to be applying pressure while driving, applying pressure to the calipers making the brakes slightly ride the disks (a valve in the master cylinder possible broken and letting fluid by)?

 

I cannot fell this in the steering wheel BTW, it's all in my seat and where my feet are while driving.

 

Things I have changed prior to me posting this:

 

Front and rear U-Joints

Rear shocks

Front brakes and metal clips

Front rotors turned

 

Sorry this is long, but I wanted to try most everything I knew prior to posting. Hopefully I have explained myself descent.

 

Any suggestions?

[8.1HD/ALLISON]

You stated it all started with the tires..... have you ever the tires checked for excessive road force? Could be an imperfection in the tires construction. I have a tire thats a little high and has a slight vibration at times. Depends on how much i drive it and if its on front i notice it more. I would start by having road force checked.

 

Sent from my LGL86C using Tapatalk 4

 

 

[chucksnee]

You stated it all started with the tires..... have you ever the tires checked for excessive road force? Could be an imperfection in the tires construction. I have a tire thats a little high and has a slight vibration at times. Depends on how much i drive it and if its on front i notice it more. I would start by having road force checked. Sent from my LGL86C using Tapatalk 4

Have not had them road force tested yet, however, do you really think that 2 sets of tires in a row, same manfacture just went from a LT to a P tire....could be bad?

[specialty8]

Have not had them road force tested yet, however, do you really think that 2 sets of tires in a row, same manfacture just went from a LT to a P tire....could be bad?

Have you checked to see if possibly you could have a bent wheel? Just a slight bend could cause a vibration.

[chucksnee]

Have you checked to see if possibly you could have a bent wheel? Just a slight bend could cause a vibration.

Only thing I did is watch them spin them on the balancer...did not look like thye were bent...

 

Thanks for the reply.

[specialty8]

Only thing I did is watch them spin them on the balancer...did not look like thye were bent...

 

Thanks for the reply.

Chuck, one thing you could try is jacking it up and putting it on jack stands , put it in gear and run it. It could be that the drive shaft is out of balance but be careful doing it.

[chucksnee]

Well guys, here is an update.

 

Took it to the dealship Monday, they did most everything they could do and nothing, road forced my tires, checked everything underneath, all was good....so the final option, bent axle.....

 

They replaced the axle today...no more vibration...$900....