1987 K75 Brake squeel..

[cat0020]

Well, I'm attempting to fix a brake squeeling problem on a co-worker's K75 front brakes..

 

I've put in new pads, bled both calipers, cleaned out both rotors.. but still squeel like mad when close to stop... though much better braking performance.

 

Short of re-surfacing the rotors, is there anything else I could do to eliminate the squeeling?

 

The rear drum brake does better braking than my boots against the pavement.. that's with new rear brake shoes even.. anything I could do to make them perform better other than having them drag all the time?

 

While test riding the K75 after brake bleed, an observation I have about K75 engine.. is it normal to have a vacuum sounding noise constant while the bike sits idle? I can't tell if the noise goes away while riding, but it is rather obvious when idling, bike seems to run just fine.

[RFW]

Well, I'm attempting to fix a brake squeeling problem on a co-worker's K75 front brakes..

 

I've put in new pads, bled both calipers, cleaned out both rotors.. but still squeel like mad when close to stop... though much better braking performance.

 

Short of re-surfacing the rotors, is there anything else I could do to eliminate the squeeling?

 

The rear drum brake does better braking than my boots against the pavement.. that's with new rear brake shoes even.. anything I could do to make them perform better other than having them drag all the time?

 

While test riding the K75 after brake bleed, an observation I have about K75 engine.. is it normal to have a vacuum sounding noise constant while the bike sits idle? I can't tell if the noise goes away while riding, but it is rather obvious when idling, bike seems to run just fine.

 

Brake squeal. If you are using EBC FA18HH pads on the front (the HH ones, not the standard FA18s), they're gonna squeal. I had the same problem when I changed over from the standard FA18s to FA18HHs. Made a hell of a squeal just before a stop. Hitting the brakes really hard eliminated the noise, but who wants to do a "brakie" at every intersection? The standard EBC FA18 organic pads seem to work just fine.

 

One other trick that MIGHT work is to put a very thin film of Dow Corning #4 or #111 silicone "grease" on the back of the pads. This stuff is sometimes supplied in a little blister container with some automotive brake pads, but it isn't a guarantee.

 

As for the vaccuum noise, it sounds suspicious to me. My '86 K100RT (which is nearly the same engine) makes no such noise.

 

Bob.

[DouglasR]

I've got a 1994 K75, brakes are silent unless they're really dirty, don't know what to tell you about that.... At idle the only thing I hear is the fuel injectors clicking a little bit, but no other sounds as you describe. I think you may have a vacuum leak somewhere, not unusual in a bike of this age. Might want to check the fuel lines, if the 1987's injector system is similar to the 1994 there's a "return" line that could be the source of your sound. The supply line enters the front of the rail, the return line leaves at the rear.

 

BTW, I absolutely love my K75, one of the smoothest and sweetest bikes I've ever ridden. Mine's barely broken in with 55,000 miles, I've heard of them going 300,000 miles! Point is, it's very much worth the effort to keep that beauty rolling, good luck!

[Ghostdad]

I experienced the same problem with my K75RT. I fixed the problem by spraying the backs of the pads with CRC Brake Squeal Inhibiter. It took about 3 times to eliminate it completely. Also a mechanic at my local dealer said he once had to use a piece of construction paper glued to the back side of the pad to get rid of the squeal on some K75's. I t seems to be a normal trait on these bikes... Hope this helps...

[cat0020]

Construction paper.. my kind of problem solving.

[Fasterpill]

Make sure the brake buttons are tight enough around the rotors. It's about $100 and 20 minutes to replace them. Auto stores sell the brake goo. I got some at NAPA; it's bright orange silicone stuff with some kind of additive, and as stated above, ought to calm it down a lot. Make sure your paper is heat/fire resistant, for those long downhill rides on hot days. The squeal is from vibration, which the goo helps dampen. It goes on the back of each shoe.

[k75duck]

I sometimes lurk here. (And ran into you guys in Torrey this summer - I was passing through on a green K11LT and stopped to chat for a while)

 

This guy has a whole page on brakes including a section on squealing.

http://pweb.jps.net/~snowbum/brakes.htm

[Argon]

I have a 1987 K75 and had a brake squeal problem with the front brakes. Somewhere, I think it was one of the other BMW web sites, I read that the anti-squeal springs from a BMW 2002 car would fit the brake pads on the K75. I bought some of these and installed them, and those did the trick. I don't recall what the part number was, so this is probably not much help. If I get the chance, I will see if I can find this again.