Its been said before that this forum is amazing in the time, effort and money it can save you. Situation: New to me 1200 GSA. Bought on ADV bike flea market, and saw where the PO described a brake problem where he had rotors replaced, took the wheels to Woody's etc before he finally got it fixed under warranty (Tires were bad). Did a fly and ride to Denver to pick it up in January and ride back to Atlanta. On the way home I thought I felt the front brakes pulse in a turn, kinda like a warped rotor. Got home and the pulsing got worse, to the point that every stop bothered me. I had spent some $ on an unexpected repair (bike is still in awesome shape) and so didn't want to spend more $ chasing down a rotor and putting on new pads. Then I read a thread that really scared me. Same year GS's and they were replacing wheels, rotors, pads multiple times to find the problems, and still had the same problem a thousand miles later or so. JVB comes to the rescue! In the middle of the thread he says he heard that some issues were caused by riders coming to redlights and holding their position (like on a hill) with their front brakes squeezed. The issue was after a high speed stop, with very heated rotors, the pads were actually melting and leaving a thin but invisible residue on the rotor and when braking, it hit that spot and felt like a warped rotor. This made sense as my brakes didn't feel like a warped rotor exactly, but I couldn't think of any other possibility. It also got worse, more pulses it seemed per revolution (multiple melted spots). The solution? Sandpaper. Yep, sanded those puppies down and now almost all the pulsing is gone, only feel residual amount cause I am looking for it. Here is the thread: http://www.advrider.com/forums/showthread.php?t=238890 I was resolved after reading the first part of that thread that I was doomed to going through the new rotors, wheels and other solutions to find my problem, and it was goin to cost a lot. Total cost? Maybe $.20. Oh, and use the back brake to hold your position at a stop. Just awesmoe. Thanks ADV and JVB.
Very cool tofigure ut and glad that it was just simple .20 cent fix. JVB... you rock. As a bit of advice also - when you come to a stop after some spirited riding - the rotors will be hot for sure - it is important to not come to a stop and just hold the brakes on in that position - as the disk/pad heat combination can cause warpage - just like it caused your glazing. This can happen in cars and is especially a concern in racing conditions. I always come to a stop - let off the brake and either roll forward or back a bit and then put the brake on - so you give the rotors a bit of a chance to cool from super hot. Best also to use the back brake. This is only if they are really hot after some hard riding but I find it is now a habit for most all stops. D.
I heard a couple of years that there is a BMW service bulletin that covers this exact subject. This phenomenon also known in the circuit car racing racing world.
Brillinat. Really good info - that would explain why I went through 2 sets of discs in 15,000 miles on my SUV (which shall remain unnamed) - and did not have such issue in decades of driving beforehand. I blamed crappy discs, but now I understand that it was the pad material. Good info, again.
Awesome! Do you think the problem could be avoided by using a different brand or pads made of a different material? --chiba
I think so. I never had problems on my other GS. I am going to try EBC or another make when mine wear down a little more. Now that I know the fix when I start feeling it grab. Hopefully I can avoid it altogether by just using the rear brake.
I wanted to add a "me too" to this thread. Just found it linked to from bmwsporttouring and it jibes with my experience. Hope it can help others avoid chasing their tails. I just bought an 07 R12RT in Dec, 16k miles. Immediately noticed the mild pulsing at very low speeds just as I'd come to a stop. Makes for a herky-jerky stop unless you use only the rear break at < 10 mph, which I started doing, but it bothered me that it was that way. read a lot about warped rotors and floating carriers, bobbins, aftermarket rotors etc.. Couldn't believe the bike could need new rotors at such low mileage. A warp seemed unlikely otherwise I would feel it at high speeds too. Later I read about differences in friction on the disc from invisible film buid-up. That sounded like most plausible explanation. Scouring the disc surfaces with steel wool/brakekleen made a huge difference for a while. In fact I was ready to call it "fixed", but the pulse has slowly crept back since then. Next front tire I am going to replace the pads, and remove and sand the rotors more thoroughly with my little B&D mouse and fine grit paper - I really expect that to be the end of it.
Just an update. I sanded the brakes several times and it always improved it dramatically. I replaced the brake pads and used steel wool to clean the rotors again, but didn't do a really great job of scouring them. I still had some pretty good pulsing, but my theory was that the new pads woiuld eventually burn/erode the old brake film. That appears to be happening. I still have a little pulsing, but it is improving.
1 - I got the pulsing brakes of my cage :huh fixed by doing a few brisk brakings. In km/h, I'd go 120 - 50 - 120 - 50 - 120 - 50 - let the brakes cool down properly before stopping. 2 - You may want to consider using emery cloth instead of sanding paper if you decide to touch the rotors. Sanding paper may leave some unwanted residue on the rotors and even make the problem worse. 3 - A friend of mine had measureable warping in the rotors of his Suzuki, but still below the serviceable limit of 0,2 mm (0,008"). (That could have been a handling issue when doing a tire change.) The rotors were carefully bent manually to reduce the warping, which actually helped!!! 4 - Another Suzuki-riding friend of mine put a thin foil (cut from an energy drink can ) under two bolts of the rotor. Problem solved. My $0.04