[Guest]

HELP!! I have a shimmy over about 58MPH - can't feel it in the steering wheel or the transmission, and have noticed it for about a year now. It shimmys for a second, then stops, repeating about every 3 - 4 seconds. Since it started, I have changed the transmission (C4 to T5), shortened and balanced the driveline including new u-joints, new tires (balanced), new tie rod ends and front end alignment - and the shimmy is still there! It almost has to be something in the rear end, since all the changes up front didn't help. Any ideas?

 

[camachinist]

Run the car through the gears up on stands and observe the action of the rear end/driveshaft/wheels...

Re-check diameter and register of rear u-joint. Check driveshaft for runout.

My last experience with this issue was at speeds over 105mph in the race car....turned out to be the driveshaft slip yoke having a little bit too much clearance in the extension housing bushing (.008" vs .003-.005")...polish yoke; make and install new bushing with correct tolerance; problem solved...

Lastly, is the shimmy completely MPH related? IOW, if you were doing 58 mph in 2nd or 3rd gear, it wouldn't change the experience, yes?

Let us know what you find out..