2003 Sable random shaking when braking not rotor problem
 

I have a 2003 Sable that will shake or pulsate when braking. The problem is intermittent. This only happens when braking and it can be slow or higher speeds. I know the rotors are the first thing that will come to mind, but I've had the front rotors and brakes replaces just a few years ago and had the rear rotors replaced last year and were told the brake pads were in great shape.


When I last had my tires balanced I asked for a complimentary brake inspection and they came back to me and said everything looked great and wondered why I even asked.


The problem is only when braking and the car shakes, not the steering wheel so much. More like a pulsating feeling. But the problem does not happen every time. I can go and drive and have a full smooth stop and later on have a shaky one. I haven't been able to narrow it down to it only happening in the morning or evening or temperature in the weather. It seems to happen regardless of any situation, flat ground or hills.


Last night I was on the highway doing about 60 and was merging onto another highway and when I slowed down making the turn on the curve the car really shook including the steering wheel. That was the worst I had ever noticed it.


I had the tires rotated and balanced about 6 months ago when I noticed it and thought that would fix it, which was not the case. Sears said to replace the master cylinder. When I had a reliable local mechanic replace the rotors I told them what Sears recommended and he came back to me and said everything look good and that Sears was probably was trying to make some money, which I knew that and would not have had that work done without getting a second opinion.


About two times the brake light would come on and go off randomly. I checked the brake fluid level and topped it off and that seemed to correct that, but I never saw any leaks from under the car.


I'm kind of at a loss because most answers I find online to this question are the rotors which I know is not the case.


Any other suggestions? Or questions for me that might help.


Thanks in advance.