front master brake cylinder replacemnt

[MachineJoe]

I'm giving consideration to replacing my front master brake cylinder myself. I checked past posts but was not able to find any info. If someone finds a post on changing one of these out please direct me to it. If someone has a step by step instruction sheet that might keep me from using my old technique which involves a BFH and a few choice words .

any advice would be great.

 

I know this would be a great tech daze project and thought about hosting one. I have a large heated building where everyone could pull the bikes into. Maybe in Nov or early spring. Any tech wizards in NE Ohio interested in working with me on this?

 

Joe

[Dr Klawn]

It's not too difficult. I just replaced mine in August due to leaking around the rubber boot at the lever. I first took it apart to see if the rebuild kit would suffice but determined that wasn't the way to go - too much pitting and corrosion in the bore. Chicago BMW had the new MC unit for $197+-. Kudos to them for there 20% off online policy! (no affiliations to them, etc.) I'm still a bit peeved at my local dealer for when when I asked why this had become so deteriorated when the brakes have been bled yearly since new, they told me that maybe I should bleed them twice a year... This seems a bit ridiculous to me. Anyways, check out the following link for a rebuild of the existing, or use the haynes / clymer books for removal and replacement. There is also to notion that if the MC needs to be rebuild / replaced, that the calipers could probably use a rebuild as well. I may do this down the road.

 

Rebuild link:

http://www.largiader.com/tech/r11mc/

 

Good luck!

[RFW]

I'm giving consideration to replacing my front master brake cylinder myself.

 

First off, is there actually something wrong with it? Master cylinder problems are usually evidenced by the lever gradually moving inward under pressure as the fluid leaks around the main pressure seal.

 

Generally, there isn't much to brake work. It is fairly intuitive.

 

One thing you might consider, if indeed there is a problem that needs work, is to simply get a rebuild kit if it is available. This is simply all the rubber parts, and perhaps the piston as well, that is available from BMW (at least they offer one for my K100's brakes).

 

After all, there is very seldom anything wrong with the main casting of the master cylinder; most problems are related to worn seals only, so why replace the entire thing?

 

Installing a rebuild kit is pretty simple, and a hell of a lot cheaper than putting in a new master. All you MAY need to do that may require a bit of cleverness, is to lightly hone out the existing master before reassembly. I usually just do this by taping a strip of 400-grit wet-or-dry sandpaper to a wood stick, then winding a couple of turns of the paper around the stick with a thin sheet of foam between the layers. This will be spun on the a hand drill, so be sure to wind the sandpaper in a direction that it won't get bunched up when turning.

 

Now, put some light oil (or better, kerosene or diesel) in the master's bore, tightly compress the sandpaper/foam on the stick and insert it into the bore. Spin it slowly with a drill, while rapidly moving the stick/sandpaper in and out to get a nice crosshatch pattern in the bore.

 

Do this for maybe 10 or 15 seconds or so them remove the stick and thoroughly wash the master cylinder in hot water with a strong soap in it. This will remove all traces of oil and grit. Then let it dry before assembling the new rubber.

 

Remember to coat the rubber, piston and bore with brake fluid before assembly. I have used this procedure countless times over the last 40 years with various vehicles, with no problems at all, and saved a lot of money in the process (Hey! my grandparents were Scottish! What can I say!).

 

Bob.

[MachineJoe]

Bob, thank you for the the details I did leave out an important reason for replacing the MC. My RT was knocked over by a teenager walking AROUND the bike to get to her car. She proceded to put it in reverse WHILE calling her g/f and ... well ..... down the bike went. Why they put teens and cars together is sometimes a mystery to me. I told her to look into those little things hanging of the side of each door called mirrors.

 

The brake lever was forced backwards during the fall and blew out part of the casting on the MC.

The local BMW shop gave me a $450-500.00 estimate so, I'll give this repair a try myself

 

Thanks for the advice I'll check out the book and give 'er a try after the snow flies.

[FREEBEE]

Looking at your avatar It would appear you ride an 02-04 R1150RT??

A used master can be had from Beemerboneyard for $105.00.

[RFW]

Bob, thank you for the the details I did leave out an important reason for replacing the MC. My RT was knocked over by a teenager walking AROUND the bike to get to her car. She proceded to put it in reverse WHILE calling her g/f and ... well ..... down the bike went. Why they put teens and cars together is sometimes a mystery to me. I told her to look into those little things hanging of the side of each door called mirrors.

 

The brake lever was forced backwards during the fall and blew out part of the casting on the MC.

The local BMW shop gave me a $450-500.00 estimate so, I'll give this repair a try myself

 

Thanks for the advice I'll check out the book and give 'er a try after the snow flies.

 

I would have told her quite a bit MORE than that. Two weeks ago I was sideswiped by some "new driver" (that's Vancouver-speak for someone recently arrived here from Hong Kong, and who has marginal driving skill). I think that he learned quite a bit of English vocabulary he may not have been familiar with, before I was through.

 

Anyway, it is clear that installing a seal kit won't quite solve your problem!

 

Bob.