Steering wheel is shaking on 1991 Mercedes-Benz 560SEL

I feel some vibration only when I apply a brake. Sometimes I notice some vibration at a speed between 120km/hr and 140km/hr. When I go over 140km/hr, vibration is go away. Please what wrong with my car.Thanks

by in Guaynabo, PR on April 19, 2011
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2 answers 2 comments
ANSWER by , April 19, 2011
Vibration felt in the steering wheel when you apply the brakes is normally brake rotors that are out of true and need to be resurfaced or replaced. Brake discs that are out of parallelism by as little as .003" of an inch can cause vibration. Wheel imbalance is a possibility but wear in suspension joints or steering rack ends could cause a vibration on braking.
COMMENT by , April 20, 2011
Hi Patrick, I am sure that the wheels are balanced correctly , I replaced almost all front joints such as upper, lower ball joints, steering damper and steering rods as well. What I suspect as you mentioned the rotors have uneven surface and may need to be machined. I will inspect rotors and do surface machining. Thanks a lot. With my best regards.
COMMENT by , April 20, 2011
MB rotors are at minimum thickness when they are new and cannot safely be machined. if you have warped rotors, they should be replaced.
ANSWER by , April 20, 2011
warped rotors