High Speed Shimmy

I have a 98 Toyota Sienna. I experience a slight shimmy at 65+ MPH. It seems to come from the front end. In addition, it seems to escalate after about 2 hours of driving. when that happens, it gets louder. To stop this, I slow down and apply the brakes. To my surprise, I feel vibration in the brakes. Under all other circumstances, the brakes are smooth. See also my list of recent repairs.



I have done the following work within the last month to take care of the shimmy, to no avail. These are listed in the order completed:

* New tires, balanced

* New lower front control arms.

* New front rotors and pads

* New rear shocks

* Alignment

* Rotated tires front to back



What else could it be? I am really frustrated…just looking for a nice smooth drive on the highway.

Wheel bearing or maybe a caliper is dragging? How long since you had the front wheel bearings greased or inspected?

I will certainly check the bearing and the caliper.
Bearing: I discussed with my mechanic. He thought not–because that sound (grinding / marbles) would be with me always. It isn’t.
Caliper: I would expect the tires to be hot after a few hours of driving, but they are not.
Thanks for the suggestions.

Caliper can drag and not heat up the tire. How about the wheel, did you feel that too or perhaps the hub? I have a '91 Camry that had a bad caliper and ground the pad down to nothing. I never heard a thing until it hit the pad wear indicator.

Wheel bearing noise would mean the bearing is going out, but it could be that it just needs tightening to remove excess play. You’ve replaced everthing else, not much left to shimmy.

Had a trusted mechanic look at it. Here is the latest:

  1. Bad motor mount.
  2. (Here’s where you get points) Dragging caliper.

(1) he noticed it clunked when putting it into reverse. Now I know where that sound came from.

Point to learn about (2), I guess, is that they get old enough and just don’t retract as they ought. Sometimes, it’s because brake dust had found its way inside the piston boot. Sometimes, it’s just because…

Will keep you posted. He’ll replace the mount first.