Re: Brakes

[Tom Cutter <tpcutter@xxxxxxx>]

<<Last year the front calipers on my 1994 R1100 RS started to stick to 
the point where if I kept going they would get so hot as to stop the 
bike. They would release after the bike sat for a few minutes. I 
ordered a caliper rebuild kit and all seemed to be OK but now they are 
doing the same thing. There is a bit of drag between the pads and the 
rotors but not a whole lot. The bike sits all winter and I am thinking 
that the problem may be the master cylinder as both rotors got hot. A 
few days ago the bike started to slow down after less than a mile and I 
believe the bike would have completely stopped if I had tried to keep 
going and both rotors were very hot. Before ordering a master cylinder 
rebuild kit I would appreciate any comments or suggestions. Can you 
also tell me what I should order. Is it just the piston in the master 
cylinder or are there seals also?
> >

You will be well served to do some research and understand exactly how 
your brakes work. If you are unsure, I would suggest that you get 
professional assistance. Brakes are "mission-critical," to paraphrase a 
local guy. Don't take chances to save a few bucks.

There is a fluid return hole in the master cylinder that allows 
excessive fluid pressure to bleed off into the reservoir when the lever 
is fully released. If this tiny hole is obstructed, the fluid pressure 
will build when the fluid heats up, causing the brakes to drag and 
overheat.

You need to check and clear tht littl ehole. Rebuilding the master 
cylinder may NOT take care of that little obstruction. Also, if the 
master cylinder is not LEAKINGl it does not need rebuilding.

Another possibility is that one of thbrake hoses is failed internally, 
acting like a one-way valve to fluid flow. This is getting pretty 
common on 15+ year-old R1100 models. We are seeing lots of hydraulic 
line leaks and failures.

Replace the brake hoses with OEM or aftermarket stainless hoses, then 
fluch/bleed the system. Use a tiny wire to clean out that fluid return 
hole, visible in the bottom of the fluid reservoir when the cap is off 
and the fluid drained. Use FRESH DOT4 or 3/4 brake fluid from a NEW, 
SEALED container. DO NOT use DOT5 fluid. If you disassemble anything, 
wash the parts with brake fluid only, no soaps, solvents, etc. When 
everything is all back together, you can clean any fluid off the 
OUTSIDE of theparts with warm soapy water, then rinse with clear water.

Tom Cutter
Yardley, PA
http://www.RubberChickenRacingGarage.com
*"To get something you never had, you have to do something you never 
did." *