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View Full Version : Unidentifiable Front Brake/Drivetrain Shimmy



nofrillls
03-17-2010, 05:46 PM
Okay, this is one of the oddest automotive ailments a car of mine has ever had...for several months now, there is an odd shimmying/shuddering that happens from time to time that appears to be related to lateral forces on the front end brakes or drive line.

It comes and goes, but I find the easiest way to make it occur is to make a hard left turn while accelerating. After doing so, there is a shaking/shimmying/shuddering that is at wheel speed, coming form the front end that sticks around for as little as a few miles or as long as a few days of regular driving. At freeway speeds you can see and feel it in the steering wheel. Stepping on the brakes when the shimmying is occurring will make the brakes pulse, squeak and clatter. Eventually the symptoms just kind of disappear, potentially after backing up or with just enough mixed driving.

Even though they did not look overly worn, I replaced the front brake pads and rotors, which seemed to temporarily limit how often the problem occurs. However, after just a few thousand miles of driving the problem seems to be back, and with a vengeance...enough to make emergency braking a very noisy and scary experience (had to slam on them today).

The only things I can think of is that one or both calipers may be intermittently dragging, or (God forbid), there is some weird lateral run-out problem with the front axles or differential, causing the brakes to rub, generating brake friction and heat.

Before I go and replace the calipers, does anyone have any ideas or advice? I'm pretty technically inclined, but this baffles me.

HELP!

Thanks.