Master cylinder swap now having problems brakes sticking.

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TAZLDAZL

TAZLDAZL

AMSOIL DEALER
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Oct 26, 2008
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Location
Virginia Beach, VA
Any advise please!

I have a 1971 Demon braket racer that has had the front drum brakes replaced with a 1973 disc barake setup. Their is also a line lock set up installed. The car ran and braked fine with the original mastercylinder. I have since than replaced the small block with a big block and I am using fenderwell headers. Some other racing friends told me about swapping out the old style master cylinder to a new style to help on heating problems from the headers as seen in pictures below. I notice that when I went to go put the car on the trailer that it was kind of dragging. Then when I went to take it off the trailer it wouldn't even roll back. infact when I put in reverse to help it off the trailer I had to give it a little more gas than usual. When the tires were on the ramps they sucked the ramps right back to the stowed postion and then the car fell off the trailer. Talked about shocked I have never had this happen before but than again I never had any problems rolling off the trailer. Thankfully no damage was done.
So my question to you all is this, do I have to change out the porportioning valve from the 1973 disc brake setup I have now to one that is from the new master cylider era say around 1985? Or do I need to look at something else maybe?
Thanks
AJ "TAZZ" Schneider
Thanks again to FABO for these forums

Original and new master cylinders

6588615753_0488bc25b0.jpg


New one installed
6588660927_47e7abf594.jpg
 
Have you adjusted the push rod length to stop the master cylinder from being on? if nothing has changed on the brake system,and the only change is the master,either the master has a problem or its partially on and dragging the brakes.A simple solution is to add flat washers behind the master to see if the problem gets less,this shows the master is not releasing the pressure,and by adding more washers,shows the problem is gone ,but needs a adjustable pushrod.If the problem does not get solved with the washers,the master is at fault,by not releasing the pressure inside.Jack up the front end and pump the pedal and see if it sticks,loosen the master cylinder two nuts 1 turn,do the front wheels still stick,go a another turn,you know what the problem is,mrmopartech
 
Yeah you need the push rod to have a bit of a gap so the master can fully release. if there is any pressure on the master when the fluid gets hot and expands and causes the drag.
 
Thanks everyone for that advice. Now that I think about it dah, I will check it out this weekend and let you know.
TAZZ
 
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