1983 Chevy C-10 Tire Balance Issue?

[pat patterson]

I can't seem to shake a balance issue with my 285/50/18 Nitto Extreme tires mounted on custom rims by American Eagle(5 spoke). I have had the balance checked 8 times at Firestone this year alone and the alignment checked as I have the lifetime alignment from them, the reason I chose them is that is where I bought the wheels and tires. I have tried 3 different locations and they all tell me the front end parts look good and rebalance the tires but it always, always shakes around 45mph. In recent years I have had the upper/lower control arm bushing replaced, the upper ball joints, Idler arm, Steering Gear box replaced. I really only drive it around town and to-and-from work, unfortunately the speed limit from my home to work is 45mph(the shake and shimmy zone).

Any suggestions?

[406Rich]

Have you lowered your truck at all, could be drive line angle....? or u-joints

[cffisher]

Wheel brgs? will it go away after 45 or is it to bad to find out?

[pat patterson]

Wheel brgs? will it go away after 45 or is it to bad to find out?

It's fine once it's past 40-45mph, it does it under load and while coasting. New bearings were installed less then 6 months ago.

[pat patterson]

Have you lowered your truck at all, could be drive line angle....? or u-joints

Yes, it was lowered recently by a reputable shop, just 2-1/2" drop spindles and lowered coils in the front and de-arched leafs in the rear with Bell Tech Nitro 2 Drop Shocks. The front U-Joint has been replaced, the rear has not, but mechanic(s) say the rear one is fine.

[cffisher]

Something that I recall happened on my 85 a weight had come off my drive shaft and it would shake the hole truck. You may want that checked.anim_25

[406Rich]

Pat, you really need to verify the pinion angle, beg borrow or steal a magnetic degree finder and just check the pinion angle and compare to the trans output angle, if it's wrong it's a matter of buying the shims to change, I doubt that they even check the angle after dropping the truck. The pinion should be two to five degrees down from what ever the trans angle is....!

[Blue Goose]

I agree with rich,I did the belltech 3\4 drop not even thinking about pinion angle.Then as I was finishing up the truck I put it on the lift,came in next morning and had trans fluid on the floor.So looking at the pinion it was almost to the point it was pointing up,so I had to shim it.