Hydraulic Brake Clutch Master Cylinder's

[madmax92104]

Has anyone tried/used an aftermarket "universal" hydraulic brake or clutch master cylinder? Do the "universals" have the same hydraulic pressure output? Is that something I need to think about? Obviously, I have no idea how these are rated.

The point being, my 2004 r1150r has the master cylinders incorporated with the controls (as I'm sure many of you know). Same applies for the right brake/controls. I'd really like to change these out with something a little more "modern" looking with detached reservoirs and swapping out the controls with newer BMW controls (like whats on my F800GSA). The wiring portion will be easy enough to do with a little modification and wire rearrangement since essentially they work the same except in a different form factor. BUT the master cylinders is the big question.

If you Google search "BMW universal Hydraulic Brake Clutch Master Cylinder's" you see some of the examples that I want to use. Most already have the switches built in for brake lights and clutch engagement so at least that parts covered.

I'd love to hear what you all think.

 

[cycleman2]

You will want to match the master cylinder piston diameter of the aftermarket or new master cylinder with the current one on the bike. That way you will still have the same hydraulic pressure.

Many of the more modern types have plastic reservoirs that are more fragile and will discolour with age. Everything becomes a price point and much cheaper to produce the more modern brake fluid master cylinder set ups than the older style as they can be used across multiple bike model lines.

Personally I would just stay with what you got if it is working.

 

[madmax92104]

Thank so much for the reply! So piston size is the key factor? Is that my only real concern?

The bike is project bike. The goal is to turn it into a street-fighting, cafe' racer, low seat, fusion thingy. I picked the bike up for a great price and relatively low miles (04' Rockster, under $4000 and 12000 miles). So I'm willing to throw a few bucks at it to make my vision a reality. So, it's not so much whether the OEM parts are working or not. Functionally, it's perfect. I have already bought a new(used) sub-frame, seat, exhaust, etc. I'm just looking to the forum for its vast knowledge base on the things I'm not exactly sure about.

I have another BMW and really love the brand and thought I'd share (and ask) the BMW loving forum for advise in my journey. So look for more off-the-wall questions from me

Any other thoughts from others?

 

[BC1100S]

Thank so much for the reply! So piston size is the key factor? Is that my only real concern?

Pretty much. A larger bore diameter will give a reduced lever travel and a harder feel as compared to a smaller bore size. Brembo makes nice forged radial units in a variety of sizes. Or you could try to find some used cast units at your local bike junkyard. Later model sportbikes (about 2003 onwards) use them. Best o' luck. Post up pictures when you're done.

 

[madmax92104]

You will want to match the master cylinder piston diameter of the aftermarket or new master cylinder with the current one on the bike. That way you will still have the same hydraulic pressure.

So piston size being greater is ok? just not smaller? Would the brakes be more sensitive being a larger pistons size? And What about the clutch? If it were greater or smaller for that matter what would be the result? Do I have to worry about blowing seals being larger? Do I have to worry about proper engagement if it were smaller?

 

[BC1100S]

So piston size being greater is ok? just not smaller? Would the brakes be more sensitive being a larger pistons size? And What about the clutch? If it were greater or smaller for that matter what would be the result? Do I have to worry about blowing seals being larger? Do I have to worry about proper engagement if it were smaller?

Bigger or smaller for a brake master cylinder bore is up to personal preference. Bigger = less pull, a shorter throw and less feel for the rider. Smaller = more pull and longer throw but is more sensitive in feel. Seeing as you're not building for the track this could be a moot point. You are correct regarding the clutch master although I'm not sure they come in a wide variety of sizes.

 

[madmax92104]

Perfect! I have the info I need. Just in case any are wondering, the master cylinder piston sizes for an 04' r1150r is .....
Clutch 13mm
Brake 16mm
Kind of a pain to get to just to see the number so I thought I'd save you the trouble.
You can find these numbers imprinted on the bottom of the master cylinders. You have to take apart the control covers to see the bottom of the master cylinder.
Now time to shop around...