Front brakes locked up

[ehumaui]

I have the chevy front brake conversion with power brake booster. The h-block still is installed. The master cylinder cap has been leaking so I changed out the master cylinder with an extra one I had laying around. It was working fine and then the front brakes locked up. They wont release unless I open the bleeder valve or let it sit for a while. Any ideas? Oh the cap still leaks with the new master cylinder.

Russell

 

[Broncobowsher]

It's one of 2 things. Either the residual pressure valve is holding the brakes on (that should only be a drag, not locked up) or the piston isn't releasing completely in the master cylinder. With the brakes locked up, loosen the bolts holding the master cylinder to the booster. That should let the piston retract completely and release the brakes. Adjust the pushrod to the correct length or put the correct master cylinder on.

 

[ehumaui]

I took off the master cylinder from the brake booster and it did release. How do you adjust the push rod? Is it done from below under the dash?



Russell

 

[Broncobowsher]

It would be the pushrod between the booster and the master cylinder (pushrod is holding the master cylinder down). Being that I have never had to mix parts on a vacuum booster system, I can't answer this off the top of my head. Just thinking that it might be better to just put the right part on.

 

[SteveL]

If you pull the mc off the booster there is a cap on the end of the pushrod that adjusts in and out. Adjust it in and tighten the locknut and life should be ok.