Master Cylinder

[stockman]

In replacing my Master Cylinder, the new cylinder gives you a rubber grommet and steel washer. They are placed on the piston shaft and fit between the cylinder and throttle housing. My question is which side of the steel washer does the grommet go on?

[Red_Hen]

Not sure which model R65 you have:  I went to Real OEM dot com, that shows schematics for BMW parts:

http://realoem.com/bmw/showparts.do?model=0365&mospid=51899&btnr=34_0598&hg=34&fg=11

If this is not your bike, go back and plug in values for your year / model and you'll see a picture of front M/C and how assembly goes.

Do you have a Clymer manual?  That would also be helpful!

Good Luck.

[Milo_357]

In replacing my Master Cylinder, the new cylinder gives you a rubber grommet and steel washer. They are placed on the piston shaft and fit between the cylinder and throttle housing. My question is which side of the steel washer does the grommet go on?

Stockman, are you by chance REBUILDING an MC?  Sounds like a rebuild kit to me, rather than a new MC.  Is this the round MC?

Dell

[Bob_Roller]

The steel washer goes on first, then the rubber grommet/boot, the rubber part is there as a dust/dirt boot for the piston shaft .

[stockman]

My question is the orientation of the dust boot(grommet). One side is a larger diameter than the opposite side creating a shoulder. The smaller diameter fits the inside hole in the washer but on which side of the washer does the larger diameter go?
I think the larger diameter goes towards the rear or closest to the brake lever.

[steven m]

The grommet fits into the throttle housing, so the tapered, or smaller end, should be pointing towards the end of the shaft.  Make sure your old grommet came out with your old master cylinder or the master cylinder won't seat properly and you'll be wondering why your front brake doesn't work.  How do I know this?  Uh....

Steve

[stockman]

Steve, if you are right then I have grommet on opposite in that the larger diameter is on the side of the washer towards the brake lever and the end of the shaft. It is working and I've got good pressure . I have not ridden it yet to see how it stops.
Thanks for the input.

[raymr]

The grommet fits into the throttle housing, so the tapered, or smaller end, should be pointing towards the end of the shaft.  Make sure your old grommet came out with your old master cylinder or the master cylinder won't seat properly and you'll be wondering why your front brake doesn't work.  How do I know this?  Uh....

Steve

Ditto on the old grommet - same experience.

[steven m]

If you take the master cylinder off again, which you may not feel like doing, and shine a flashlight into the throttle housing, you can clearly see how the grommet fits, leaving a flush face for the washer.  The old grommet being in place is what kept my brake from working.

[stockman]

Tomorrow after work I'm taking it off. I've got I wrong. Not hard to take off really. Thanks all for the input.