Front brake rotor replacement

[Acpantera]

Ok, so it is silly season for me(snow and salt season). I was recalling some of my last rides and thinking about the brake feel. At the point just before a stop I have noticed a less than smooth feeling. As my brake lever never did seem as firm as it should be and the lever travel a little too much, I'm thinking of renewing the front rotors(and pads). Has anyone found any problems as far as warped or inconsistent surface in the rotors?? Has anyone used aftermarket rotors? I have renewed the rear rotor with a new one from the beemer bone yard and it seems to be ok(I will be putting a dial on that too). Any suggestions on brands or installation? Thanks,
Tom

[deilenberger]

The symptom of a shudder just before a stop (based on way too much experience on K75Ss) is usually one involving the surface of the rotor(s).. on the K75S it was caused by the pads rusting to the rotor after washing the bike. It left a spot with a different friction coefficient then the rest of the rotor. Once it started on the K75S the only answer was new rotors - and I was replacing those $$$ SOB's more often then tires.

Before replacing the rotors you might try a few things - if it's a mild case - I've heard of people having good results from this:

1. Change to an EBC "HH" sintered pad - and brake hard for a while. The sintered pad tends to scrub the surface of the rotor. Some people used full-on race pads (VERY hard pads) just to clean the rotors, then put the normal pads back on.

2. Fine sandpaper or a rotor hone. 3M makes a kit to rough the surface of a rotor up.. fits in an electric drill and has several grades of paper. It's pretty much like a spinning-disk sander setup. There are also brake hones made for electric drills - these are hones that look sorta like a shower head - with wires coming out like the water would, and abrasive lumps on the ends of the wires. You hold it against the surface of the rotor and turn the wheel while it's spinning. Both are not so easy to use on the inside rotor surfaces without removing the rotors.

If that doesn't work - then I'd see if EBC has a rotor fitment for it. They were the only vendor who even was willing to discuss the problem with me - and a set of their rotors on the K75S ended the rotor issue (after going through at least 6 sets..) for me. I used them with the HH pads from EBC. The current owner of the K75S has reported no problems to me (he's a good friend, it's a bike that swaps between members of our local club..)

As far as the too much travel syndrome.. it's sorta "they all do that" (if not now - eventually..) It's my belief that it's caused by the caliper pistons withdrawing too far when you release the brake. Bleeding doesn't really do anything long term. What has worked on mine for a while was pushing the pistons all the way back into the caliper, then pumping them back out. I think that resets the square O ring used to provide pushback resistance. What might work longer term is a caliper seal refresh.

I've learned to adjust mine so it just doesn't pinch my finger when I pull the lever all the way back. I have grip puppies on my grips - so that would be lots less of a problem for most people. That seems to provide me with adequate braking, even if the travel is more then I'd desire. Brand new R12R's don't exhibit this behavior - and new pads might help just because of the position of the pistons being further back in the caliper bores. Been meaning to try that (I have a set of EBC pads waiting to go in - but the stock ones are SO new looking I haven't been motivated..)

IMHO - EBC makes good brake stuff at a fraction of the cost of stock. I have no hesitation suggesting them.. and when I've contacted them, they've been responsive with answers or at least thoughts..

Good luck - and let us know how it works out.

[M249Joe]

Replaced my rear pads with EBC sintered and the brake dust issue on the rim is gone....

[mogu83]

EBC seems to be the 'go to' aftermarket brake. I put an EBC rotor and HH pad on the back of my R and I'm happy with it.