PCCB uneven braking at low speeds
03-25-2017, 06:09 AM
#1
Racer
Thread Starter
PCCB uneven braking at low speeds
Hi all,
At low speeds, my PCCBs have never been particularly smooth. They act as if there's pad transfer on the discs so when I brake lightly at low speeds the deceleration isn't consistent, it's as if the brakes are pulsating slightly. The strange thing for me is that at high speeds and moderate to high braking, the brakes behave beautifully. Is this just normal with these brakes, or is something odd going on?
Thanks in advance,
-n.
At low speeds, my PCCBs have never been particularly smooth. They act as if there's pad transfer on the discs so when I brake lightly at low speeds the deceleration isn't consistent, it's as if the brakes are pulsating slightly. The strange thing for me is that at high speeds and moderate to high braking, the brakes behave beautifully. Is this just normal with these brakes, or is something odd going on?
Thanks in advance,
-n.
03-25-2017, 09:30 AM
#2
Rennlist Member
My brakes do not behave in that manner.
03-25-2017, 11:02 AM
#3
Rennlist Member
Not a brake expert, but if similar to steels, could be some deposit. Go to DIY car wash and do a high pressure wash out of holes in rotors. Then try ...
Similar to bedding in new pads, find a safe place (280 off ramp on a Sunday morning early) where you can do 3 consecutive 80-20 mph hard stops. If not solved, take it to Carlsen and ask for Beto.
Similar to bedding in new pads, find a safe place (280 off ramp on a Sunday morning early) where you can do 3 consecutive 80-20 mph hard stops. If not solved, take it to Carlsen and ask for Beto.
03-25-2017, 01:30 PM
#4
Race Director
Hi all,
At low speeds, my PCCBs have never been particularly smooth. They act as if there's pad transfer on the discs so when I brake lightly at low speeds the deceleration isn't consistent, it's as if the brakes are pulsating slightly. The strange thing for me is that at high speeds and moderate to high braking, the brakes behave beautifully. Is this just normal with these brakes, or is something odd going on?
Thanks in advance,
-n.
At low speeds, my PCCBs have never been particularly smooth. They act as if there's pad transfer on the discs so when I brake lightly at low speeds the deceleration isn't consistent, it's as if the brakes are pulsating slightly. The strange thing for me is that at high speeds and moderate to high braking, the brakes behave beautifully. Is this just normal with these brakes, or is something odd going on?
Thanks in advance,
-n.
I guess it is possible for this to happen to PCCB's.
You can try some kind of bedding in process but I suspect you will be unsuccessful in getting rid of the pulsing.
For iron brakes the only "fix" is skimming the rotors or replacement. Neither of which is practical for PCCB brakes.
What I did when one of my cars developed pulsing brakes -- after an emergency stop from high speed with very rusty rotors, rusty because I let the car sit a day or two after washing it without taking the car out afterwards and using the brakes hard enough to dry them -- is I just adapted a slightly more agressive braking style using a bit more braking force and avoiding the very light braking during which time the pulsing would occur.
Not only did this eliminate the pulsing but it is a braking technique/style that delivers better brake life.
I drove the car to over 140K miles and sold it with the original brakes and still with plenty of life left. During the test drive the buyer -- a woman -- of course was the typical very light and early braker and she noticed the pulsing but bought the car as it was. I'm sure afterwards she had the brakes done.
03-25-2017, 04:22 PM
#5
Racer
Thread Starter
Figured it out- it was the PDK. Under light braking it doesn't declutch until it's sure your intention is to stop, so the interaction between the powertrain and very grabby PCCB was causing the behavior. Verified by braking in neutral. Thanks all for the advice.