Did a Dual Master and Power Brake conversion on a '50 truck. Brakes were functional before the conversion so no other changes. After the conversion brakes work great exceptthey will lock up. This seems to happen when driving in town and braking a few times, then they lock. Letting it sit for fifteen minutes brings them back to normal. Rod is adjusted. Any suggestions as to what this could be?
If it is the rod why does it not lock up all the time? If it is the rods, put more slack on the booster/mc side?
Been a common topic with masters and push rod length. Return holes in master covered by piston and building pressure with heat. One instance I've dealt with was on a '64 Impala that measured too long on the master end. Manufacturing tolerances?, combo even came together as a set. Needed to remove the threaded end, grind a bit off rod and reinstall with Locktite.
the rod sounds like a winner. Crack the line going into the master and if fluid squirts out and the brakes free up then the fluid isn't getting back the reservoir.
You could loosen the nuts holding the master cylinder and slot some washers to slide in and tighten it back up to try.
I know this an old thread but I am having a very similar problem only with a twist. I installed my aftermarket set up 4 months ago on my daily driver and am now having lock up issues? Any quick advice, and just outta' curiosity what would cause it to start having problems now? Oh, and mine doesn't free up when cooled off.
Bad flexible lines. Bad return spring. Out of adjustment. Sticky parking brake cable. Could be lots of things. Get them to stick, then start looking for where the pressure isn't being released. Sent from my iPad using The H.A.M.B. mobile app
Turned out to be adjustment. It had to be just right with no pressure on the master cylinder. Bought a new second dual drum master cylinder thinking it was that. Looking to sell that for about half price ($150).
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