BimmerRob08 wrote Damn, Inddont realize they were than much thinner. I used to have the older APracing BBK front and back, which the calipers look like the Peragon ones but had the floating strap drive type rotor design. Ended up having a brake applied vibration that was pretty violent at around 86mph seemed to be the sweet spot. I did all sorts of testing and even changed out calipers, rotors. Etc. with the assistance of Stilen at the time where I purchased them. I believe was a gyroscopic precession issue when the brakes where applied. Ended up selling them and went back to stock. No vibration now. I do remember the pads where much thicker. How would these compare to OEM pads and if just mainly street use?
My e46 M3 uses an AP Racing front caliper since 2004 that’s virtually identical to the Paragon PA035 caliper and it also uses an 18 mm thick pad. I always go to the track with a brand new set of backup brake pads so I wouldn’t run out of pad material for the track and street ride home. I’ve changed a lot of pads in the paddock since 2004 due to the 18 mm thick pad. I believe the Paragon PA025 rear caliper uses a 16.5 mm thick pad. Also, just as an FYI, Paragon rotors and calipers (PA035 and PA025) are manufactured in China which explains the low cost compared to other track/race brake kits.
Did you try a different caliper adapter bracket while chasing the vibration? It could create a radial offset and/or a non-coplaner caliper with the rotor surface. Just for troubleshooting, did you try swapping the left and right rotors? Not sure how you’d get a gyroscopic precession effect with the braking system? Maybe with a mounting hat that wasn’t rotationally concentric with, and parallel to, the hub? However, the same mounting hat design, even with the strap drive mounting scheme, is used on the left and right rotors. I wonder what would happen if binding occurred on some straps on one side of the rotor and then overconstrained the rotor from expanding symmetrically? I’m unaware of any other e9x M owners that had/have the same issue as yours with the use of strap drive rotors but that doesn’t mean others may have experienced it.
How does the Paragon PA035 caliper 18 mm thick pad compare to stock pads? The surface area is considerably larger than the stock pad which can reduce pad temperature and decrease pad wear rate compared to stock. For primarily street use with a street pad compound, the Paragon 18 mm thick pad should have superior wear rate compared to the stock 19.5 mm thick pad due to the PA035 pad having more surface area. You’ll need to be careful with dirty pistons from street and track use because Paragon calipers use internal seals and internal dust boots. Internal dust seals can withstand track use better than external dust seals but the can still get damaged/melted. I’d still strongly recommend cleaning the pistons with a rag & a waterless car cleaning product as well as use compressed air (blowing air only laterally onto the pistons) before compressing pistons back into the caliper. Furthermore, I personally will not drive my cars with brake kits on roads pretreated with brine/salt and when roads still have salt on them after a snow storm, if this applies to you.