Originally Posted by espooner
On my '02 Boxster S, I have Pagid Orange pads for the track. After 3 days at Watkins Glen, there was a severe pulsation on braking, which appears to be due to pad build-up on the rotors, according to knowledgeable people at the track. There was a fair amount of pad material plugging the cross-drilled holes, which I drilled out, so I think this theory is quite probable.
My question is how do I best clean the rotors? One friend suggested brake cleaning fluid and a Scotch-Brite pad and lots of elbow grease. What has worked for others? How do you clean the INSIDE surface of the rotor (toward the centerline of the car)? I'm a fairly proficient DIY mechanic, but don't want to pull the rotors off, again, just for cleaning.
Any helpful hints would be appreciated. Thanks in advance.
I believe you misheard or misunderstood what you were told. There is pad build upon the rotors but cleaning the rotors will not remove the build up.
The very few times -- thankfully -- I've experienced this is with new pads or new pads and rotors present and prior to performing a proper brake bed in operation and bringing the car to an emergency stop and leaving the pads (now very hot) in contact with the (very hot) rotors.
(Once this happened with properly bedding brakes when I washed my car and left it sit with wet brake hardware. Rust built up of course which under normal circumstances will be removed with no problems when the brakes are used. However, I had to bring the car to an emergency stop from high speed before I used the brakes enough to remove the rust and afterwards the pulsing was present. Not severe, thankfully, but present nonetheless. I always drive a car after I wash it to use the brakes enough to comletely dry the brake hardware.)
Anyhow, an emergency stop from speed results in the natural deposition and removable of pad material to the rotor being interrupted and some pad material remains on the rotor.
When this happens the friction characteristic of the rotor is changed to have less or more friction where the pad material was deposited and remained on the rotor.
In the several cases where this has happened I tried to perform a brake pad bed in operation to undo this condition but was not entirely successful. I believe in one case the condition's symptom was reduced but not eliminated. I learned to live with very light pulsing.
The only surefire cure/solution I know of is to resurface the rotors -- if they have the thickness to allow this. The resurfacing doesn't have to remove much material, just a skin cut in machining parlance.
Once the rotors are recut and for new pads or new rotors and new pads the brakes must be subjected to a brake bedding in process to help ensure this uneven deposition of brake pad material does not happen.
Also, at the track it is very important to take a cool down lap to give the brakes time to shed the considerable heat they accumulate. Failure to do this can result in uneven deposition of the brake pad material when the car is brought to a halt.
You can try to rinse/clean the brake hardware and of course make sure the holes in the rotors are free of any debris but I would be very surprised if this eliminated the pulsing.
Rotor resurfacing I believe is your only surefire course of action.