moparmatt89

I just recently switched from a 25 inch tall tire to a 28 inch tire in the back. They are the mickey Thompson Indy Profile they are about 12.40 inches wide total and the tread is about 10.5 inches. I had them balanced. When I am driving down the road it will be fine and then suddenly it will start to really shake, not like a vibration but a violent shaking. I look at my speedo and i am only going about 20-25, so i step on the pedal and go faster and the skaking goes away. It feels almost like wheel hop, or like i have square instead of round tires. i have traction bars, but The leaf springs are original and no longer curved but straight, so that may be a problem. I didnt notice this before i switch the tires the other day. The entire front suspension was replaced including the power steering parts aswell, it was profesionaly redone and aligned becasue i didnt feel like messing with the suspension myself. The motor mounts are new and the engine doesnt move at all when i rev it, so i dont think that it an issue. I took it on the highway the other day and it ran smooth as silk, but at low speeds through town it was violent. I also jacked up the rear of the car and spun the rear tires tomake sure they spun straight and they did.
Any Ideas?
Thanks alot
Matt

Scott H.

Can you tell where the shaking is coming from?
Is it through the steering wheel?, your seat?, or the body of the car? Front or Rear? Left or right side? is it consistent every time at that speed? or only intermittent? And if it's only intermittent what are the conditions (crown of road? accelerating/decelerating, turning, etc). Does it do the same thing on a smooth dirt road? What are your tire pressures front and rear? When was the last time you serviced your Trac-Lok?
Also you said the wheel rolls straight, does it also roll perfectly round?

Before you drive it too much more, I'd look at the following:
Wheel bearings/axle bearings, idler arm, pitman arm/steer box, loose front end components, shocks, shackles, U-bolt torque, lug torque.

You've put more weight bias up front, this may have changed your alignment, so if you don't see anything obvious, I'd suggest you have them check all 4 wheels for alignment (rear toe from a bent axle tube can cause this as well).