Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
By plugging the port you are preventing the piston in the master cylinder from moving, so you can't get any pressure applied to the fronts. You might be able to accomplish what you want by disconnecting the rear line at the combination valve. The system is designed to function on one end if the other loses fluid. You might lose all the fluid rather quickly, too.
Short of going to a single-circuit master cylinder, the only other solution I can think of is to route a tube from the rear line back into the master cylinder some way, but I don't know what the multi valve would do under those circumstances.
There must be a better way. I'm not a huge fan of rear disk brakes, but this might be a good application.