Master Cylinder P. D. W. A shuttle problem

[lgray001]

I'm trying to rebuild one of the two master cylinders I have, but I can't get the P. D. W. A. shuttle removed on either one of them to replace the O-Rings.

Does anyone have a suggestion on how to get it out?

[Stag76]

There's a small pin hidden under the rubber insert in the forward reservoir mounting point
that locates the piston.
You can pull it out easily with pliers or similar, and that allows the piston to be removed.

[Stag76]

Sorry, I may have told you something you didn't need to know.
Are you trying to dismantle the master cylinder, or the proportioning valve mounted on the inner guard?
If it's the valve you're working on, please disregard my previous post.

[FI Spyder]

I'm assuming you mean the small piston that operates the brake failure switch. As it doesn't move (except during a failure) it tends to get frozen in position on almost every brake cylinder. There is a high cam that the switch rides on, I got a larger screwdriver in there to lever the piston free after which the piston came out quite easily. Probably wouldn't hurt to load it up with penetrating oil and let it sit for a couple of days before trying. After overhaul and installation, don't put the switch in until everything is adjusted and working (system bled).