1989 Ford Taurus:
Vibration after Front Brakes Replaced

Question:

I have a 1989 Ford Taurus with 62,000 miles. When I apply the brakes at 30 mph and faster, I feel a strong vibration and the steering wheel shakes. I brought the car into my mechanic and he replaced the front and rear brakes. I still have the same problem. Any ideas?

Answer:

First of all, did your mechanic resurface the rotors and/or drums? If the answer is no, the answer is simple. Go back and have them resurfaced.

The reason behind machining brake rotors and drums is to leave them "turning true" with a flat, uniform surface for the brake linings (pads, shoes) to ride on. This is accomplished with the use of a brake lathe. The lathe, when used properly will turn the rotor or drum and cut a clean, new surface with the use of a hardened machining bit. Normally, this procedure will leave you with smooth and efficient braking, as opposed to a pulsating brake pedal, a shaking steering wheel or a vibration throughout the vehicle.

There are different opinions on brakes, depending on to whom you talk to. Some say, if you have no vibration or pulsation while braking, replace the linings and don't bother resurfacing. Others recommend resurfacing whenever replacing the brakes. Responsible technicians go with option two.

I've seen cases of linings being replaced without machining because braking was smooth at the time. Often, halfway through the new brakes a vibration develops and it ends up costing more time and money then if you did it right in the first place.

According to your description of the steering wheel shaking, your problem is up front. Presuming the rotors have been resurfaced, let's look at the other possible causes. Number one, the rotors may not have been resurfaced properly (improper mounting on the brake lathe). A rotor could be bent or cracked and cannot be resurfaced correctly. The rotors may be too thin (beyond specifications), and once you get them hot, they become warped and cause the symptoms all over again. I have even seen rotors with porous castings (bubbles in the metal) and no matter how many times resurfaced, they cause problems. The fix for all of the above is replacing the rotors.

Another possibility is a problem with one of the hub and bearing assemblies which the rotors mount to. It may be bent or out of whack from the last curb you kissed, and the rotor in turn wobbles right along with the hub. Also, a loose wheel bearing at the hub may give you a similar effect upon braking. This is not good. We're talking about a wheel flying off the car if the problem is ignored long enough.

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