I have a nasty shimming from the front when I brake. Car: 1998 Bonneville SE. I had all the tires rotated and balanced. The brakes are new. The shimmy is intermitant and only at high speeds. Any ideas?

 

It's been a while since you posted, but I thought I'd reply anyway. Warped rotors. Have them turned. You probably already did this when the brake padswere replaced, but if the kind of driving you do lends itself to hot brakes, the rotors will warp again. This can happen pretty fast in the right conditions.
Keith
1994 Bonneville SSEi

 

Well I was thinking more like the inner tie rod being that the shutter is intermitant. what do you think. Thanks for the reply.

 

Well, there are actually several things it can be. Warped rotors are just the most common. You could need a front end alignment, the rear drums could be out of round, your front brakes could have uneven pad wear caused by a caliper not working properly (sticking and releasing or not sliding properly, although that would most often show up as brake pull). A bad caliper could be causing it even before uneven pad wear occurs. Front suspension wear could also be causing it, as you noted. I just went with the most common cause. Brake overheating, often caused by hard braking, then holding the hot pads against the rotor, like at a stop sign or red light etc., often causes rotor warp even without showing excessive pad wear. Mountain driving, street racing, in other words, hard driving.Jack the car up (put it on jack stands), unlock the steering column and have someone turn the steering wheel sharply from side to side. You should be able to see slop in the steering gear if there is any. Check all connections that move.
Good luck.
Keith
1994 Bonneville SSEi

 

Check the ball joints.

 

If you have checked all of the obvious... Brakes, bearings, tie rods etc... Have someone check for loose bolts near the tie rods and Axel's. I had the same issue and it was a loose Bolt.

If you brake and stop slowly, and there is no shimmy, but yet when you break at higher speeds there is a shimmy... The weight of the body of the car is shifting when it shouldn't.

Good luck!