Mineral Oil - Clutch Master Cylinder

[JED]

I'm curious if anyone might know why the clutch master cylinder fluid changed to mineral oil.  I need to utilize the clutch master cylinder (left) to actuate the front brakes and brake master cylinder to actuate the clutch due to a disability.


I've done this conversion on several Honda's (VFR, Valkyrie, Goldwing) successfully.  I believe I can re-purpose a 1150 DOT 4 clutch master cylinder and modify cable lengths and fittings for use on a 2014 R 1200RT.  Just asking for shared thoughts?  Someone suggested it was simple done to be environmentally friendly but I think there may be more to it than that.


I'd like to communicate with BMW engineering but haven't a clue where to start.  Thanks in advance for your responses. 

[guest2360]

You need to contact your local BMW dealer.  I'm sure they will point you in the right direction.

[David.]

I'm curious if anyone might know why the clutch master cylinder fluid changed to mineral oil.

It looks like BMW changed the clutch to mineral oil because it is not hygroscopic, (i.e. does not absorb moisture), unlike brake fluid.

It does not require changing (ever) and of course is non-corrosive if it happens to get on the paint.

[David.]

I believe I can re-purpose a 1150 DOT 4 clutch master cylinder and modify cable lengths and fittings for use on a 2014 R 1200RT.

Looking at the Service Schedules for the 1150's & 1200's, the clutch fluid required changing on the 1150, but not the 1200.

This may be when the change was made to mineral oil. The seals behave differently in brake fluid & mineral oil.

http://www.largiader.com/articles/mineral/

Found this thread on UKGSer, sounds like the same conversion you are wanting to do,
http://www.ukgser.com/forums/showthread ... T4-or-DOT5

[JED]

Dave,


Thanks for your response this is exactly the info. I was seeking.  I am working with a BMW service shop but this is not a common issue that they would address so I'm attempting to help them with the research.  The UKGSer threaded address the clutch slave cylinder seal issue with DOT 4 and the solution of utilizing mineral oil in the front brake master cylinder.  Good stuff!