Where To Look Next To Stop Bounce/vibration

[KyRob]

Put new tires on my 04 Sierra xtra cab 4x4 and when I hit 43 -45 mph, there was a bouncing motion throughout the truck. The tire store changed all 4 tires one at a time and it continued to do it. They then put on another set of new tires, different size and brand and the truck still bounces. You can feel it more in the seats than the steering wheel. You can see the top of the tailgate bounce as well. I took it to the dealer and had a 4 wheel alignment done and had the tires rotated and balanced again and it still does it. The spec sheet shows everything is well within spec. This was all within a month or less of putting on new tires. I bought a set of Bilstein HD shocks hoping that I had a bad one. No dice. The bounce is still there. Gettin pretty tired of this as I can now feel up to 60 mph to some extent but it feels more like a vibration at this speed. I am planning on having the driveshaft checked for balance and the check the rotors to see if one of them is warped or something of that nature. Plan on changing the U joints as well. Not sure what to really look for as it feels like a tire but after 2 different sizes and 2 different brands, I find it hard to believe both sets would do the same thing. Never noticed any of this with the worn out GY tires. Could a rim be bent and still balance out on the machine? The dealer used a load force balancer if that matters. Any of you mechanics have an idea if I am on the right track or have any ideas on what to look for. I am really starting to hate this truck.

 

Thanks for any info and sorry this is so long,

Rob

[2000DV4.8]

I'm no mechanic by any means, but the first things that come to mind are bent wheel, and driveshaft out of balance.

 

I'd also check for any play in the u-joints, wheel bearings, ball joints, and tie rod ends.

[pennzoil29]

It looks like you've covered the basics. My first thoght would've been a tire out of round, but not likely with all you've been through. A warped front rotor, I think you would feel more in the steering wheel and front end. I hope you get it figured out.

[2000DV4.8]

Also: Do you have aftermarket wheels?

[KyRob]

Thanks for the replies guys. I have the stock steel wheels on it. I was thinking maybe a rotor as it has the disc brakes all around. I am hoping to find someone I can trade tires and wheels with for a few minutes to rule out the bent wheel idea. Plan on getting the driveshaft checked when I get time to go to the only place I know that does it. Anyway, thanks again for the replies and I will check back and update as I narrow the options down.

 

Rob

[papastoy]

Have the dealer or your mechanic check the pinion angle too. I had a 75 Camaro with a vibe at 25 and the dealer found the pinion angle off due to bad leaf springs from the factory.