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Old 11-07-2012, 03:05 AM   #12
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I too rode high performance disc brake motorcycles for many, many years. The guy before me (elizabeth) apparently never ran into certain brake pad/rotor combinations which take brake pad material and embed it into rotor surface, the harder you brake the more it does it. The only way to get back to even stock braking then is to resurface rotor provided enough material left on it to do so. You can even still use same pad.

I do not ever recut rotors on hardly anything but on standard Focus with stock Ford pads that is probably a big fat mistake. Around 70K-80K they will experience a huge drop off in all out emergency braking, with the car not able to even think about locking up the fronts even if you BEND the brake pedal trying to, don't ask me how I know that. Panic stops at that time will give you heart attacks since the car will barely even slow down. Two of the cars taught me so. Simply changing pads alone does nothing to correct it. After cutting rotors most of the braking came back and then brakes could be locked up again with much less effort. Before, you could not brake hard, car actually felt like brakes had gone out but nothing wrong with them hydraulically at all. You could look closely at the rotor surface, there were blotchy darker areas where the pad material was welded and smeared into surface, even heavy sandpaper would help the braking at that time, but a lot of work.

Never saw that issue before on any other car. Of course that means literally nothing, because these damn sure do it.

My two are not SVT but I do observe enough to know that even ONE very hard panic stop on these can overheat a front disc enough to make it act like warped, you will feel the out of round bump at a slow roll until the disc cools back off. Then it goes back to running smoothly. Nice.

The scratch wear is not important unless very, very heavy, most discs scratch up good enough to freak out people in about two weeks or so. They will still work fine then and for much, much longer. In the old days there was no need to cut discs at all, the pad material had asbestos in it which did not wear rotor hardly at all. The switch nowadays to semi-metallic pad to make up for the loss of asbestos has made modern discs wear at virtually same rate as pads, i.e., you will replace them generally more than recut them. I've seen .100"+ of wear in only 2 years, in the '60s and '70s there was not that much wear in 20 years.

I also discovered long ago how to recover any pad that had brake fluid, WD40, or oil contamination on it to work again like new. I've never dumped pads for contamination at all, simply clean them and reinstall and use.
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