Installed a dual mastercylinder in a 39 Ford. It has openings on both sides for lines ( four in all ) I didn't have any plugs to plug off the ones I didn't need so I ran both sides into a tee and then to each end of the car. Hope I'm explaining that clear enough. Both rear outlets into a tee and to the rear axle, same with the front. Well after driving for about 5 minutes the brakes locked up. I replace all the calipers ( 4 wheel disc ), same problem. So I pinched off the cross over line so I was getting fluid from just one side and that fixed the problem...but now I want to know why did it not work? I wasn't getting any "extra" pressure ..or I didn't think I was. Any ideas?
Don't believe the "T" set-up would cause a problem other than extra fittings to leak. Remove the M/C cover and make sure the piston is not covering the compensating port, in the bottom of the resevoir, with the pedal up. Should be able to see the piston move, past the port, as the pedal is pushed down and move back past the port with the pedal up. If the port is blocked there is no way to relieve the brake pressure upon releasing the pedal. adjust the push rod so the piston opens the comp. port.
41 is right,make sure the mastercyl.pushrod and mastercly have a little end play.To tight and pressure will not release,then fluid heat will cause expansion and brake lock up.
Ive come across this problem as well myself, a little adjustment to give more play in the pedal and problem solved. As already stated a return spring on the pedal will definatly help as well.
Glad you got the problem fixed. I would have thought it would work the way you had it. I would plumb it with as few fittings as possible though, change M/C, too many holes.... LOL
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