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"BREAKS" again (from July 9)

My 1999 Taurus developed a vibration this summer. I noticed it only when applying the brakes. I have had the back brakes repaired (the works - $600 worth), and the mechanics assure me that the front brakes are fine. The vibrating, however, is distinctly worse. While they had it in there, they inspected it, gave it a sticker and claim they can’t find a reason for the shaking. Any ideas on what’s being overlooked? The treads on the tires are fine, but they are 3 years old…

After taking a look at your other post you state the problem is more of an “up and down” thing rather than a vibration.
Do you mean the nose of the car appears to feel as if it’s lurching a bit or do you mean the brake pedal is moving up and down a bit?

A steering wheel vibration is usually caused by warped rotors or a loose wheel bearing, worn suspension part, etc.
A lurching or brake pedal movement is caused by front rotors that have a parallelism problem or by warped rear brake drums. You state the rear brakes were completely redone but if the people doing the brake job overtightened the rear wheel lugs with an air wrench then the new or machined brake drums could have been ruined. Overtightening wheel lugs will distort a brake drum very easily.

Take the car out on a smooth deserted road, run it up to about 45 MPH and then bring the car to a halt slowly with the park brake only; no foot brake.
Note if the problem goes away. If the problem remains it’s in the rear; if it’s gone then it’s in the front. Hope that helps.

Does this car have ABS? Could ABS activation be what is going on here?

If your ABS is activating itself when it shouldn’t, you will need to find a mechanic who is better at diagnosing and fixing ABS systems than your current mechanic.

Have you gotten a second opinion or have you been going to the same mechanic all along?