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Discussion Title: Pulsating brakes
| Mustangman25 |
2005-04-27 17:06:00 |
Pulsating brakes
For the past few months now, I've been having a pulsation in my brake pedal any time I step on it...the more I press, the faster it oscilates. When I bought the car about 7 months ago, the dealer replaced the pads, shoes and front rotors, so I figured it was the rear drums out of round, as they have 60,000 miles on them, but then I realized that there is a shaking in the wheel that matches the pulsations exactly which led me to believe that it was a problem with the front brakes...everything checked out; pads are still very good, and the rotors are still well within manufacturer's specs. Can an out of round rear drum cause the wheel the shake? Does anybody have any other ideas what it could be? I'm afraid of hard braking now with such a bad shaking pulsation.
BTW-2000 Focus with no ABS.
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-Chuck
Black 2000 ZX3
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| MagicRat |
2005-04-27 18:54:00 |
Re: Pulsating brakes
Quote:
Originally Posted by Mustangman25
rotors are still well within manufacturer's specs..
Usually specs for rotors refer to minimum thickness. This is easy to check, but generally, 'runout' is more difficult to check. This is the sign of a warped rotor and your most common cause of brake pulsation.
I would suggest have the rotors machined. Installing a new set of pads is a good idea, because the old ones will have developed a unique wear pattern.
Also, check out the front end for out of round tires, alignment difficulties (often both show up as abnormal tire wear) and look for worn or damaged steering and suspension components, including wheel bearings.
Chances are the brake work will fix the problem; if not, take a look at these other problem areas.
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| saturnsc2 |
2005-05-03 09:57:00 |
Re: Pulsating brakes
i've bought new rotors that are warped right out of the box & that could be the problem. i know mechanics that will actually take a light cut on brand new rotors for this reason. out of round tires/distorted wheels can cause similier problems that can make it seem like it's the brakes that are out of round..
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| curtis73 |
2005-05-03 11:39:00 |
Re: Pulsating brakes
Rotors don't warp. It is the oldest and widest misconception in automotive history. They get depositions of abnormal material and the friction qualities are modified in certain parts of the rotor, but the runout you get is from load inconsistencies, not heat warping.
http://www.stoptech.com/whitepapers...rotors_myth.htm
You can temporarily solve the vibration by machining the rotors but if proper pad break in procedures aren't used it will come back very quickly, which is probably why SaturnSC2 had pulsating very soon.
Rust, pad material fusing, inconsistent pad application; all contribute to pulsating pedal, but make sure you attack the problem not the symptom.
Also, make sure you're diagnosing it right. In your post you say that the harder you press the pedal, the faster the pulsation. If that's the case, then it can't be a rotor issue since it would pulsate at the same speed the wheels turn regardless of how much you press the pedal.
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