Thread: 1932 ford disc brakes locking up

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I have double checked the residual pressure valve is installed correctly.

A couple of "out there" thoughts. First, you've never mixed any DOT 5 fluid into your system, have you? It can cause you all kinds of grief. Second, what's the age & condition of your flexible hoses that run from chassis to caliper? Rubber breaking down in a flex hose can create a "check valve" of sorts, but it's a stretch for both of them to go bad at the same time...

Have you been able to determine if the drums are affected as well?
What about the rubber hoses and fluid - did you replace fluid with silicon? and the hoses have swollen so that when heat is generated at the caliper the pressure cannot escape? It becomes easier to apply the piston than to send fluid back to the master cylinder?

do you still have the first master cylinder so that you can check how far in the rod end seats?????????there have generally been 2 different lengths over the years and I think it came about because of power/manual brakes along about the time era of the separate front/rear brake systems------------

Get off the puter, put a spring on it and DTPOOI

Originally Posted by DA34GUY

Get off the puter, put a spring on it and DTPOOI

Don, While I understand fully what you're saying, my under floor master (both clutch & brake) are working just fine without any springs pulling the pedals back. Given the leverage of the system and the placement of the fulcrum point relative to the pedals I can't see how gravity could "bounce" the system enough to offset the plunger or keep it from fully returning to the retracted point. I think this gremlin is somewhere else, especially considering that this car was driven for more than six years without problem until it leaked.

I have a busy week at work so hopefully I can get some work done on her this week end. I am thinking I should replace both brake lines if that doesn't get it then I will eliminate the residual pressure valve thanks for all the help at least now I have a direction to go. I will post up the resolution once I get it figured out...

I am pretty sure it was dot three because I found the receipt in the folder for dot 3 plus I found the bottle in the garage labeled hot rod he was pretty crazy about being organized. Either way it's worth checking the brake lines.

This is a bit embarrassing but I did say that I would report back. The master cylinder is good the pushrod slipped out of the pocket its supposed to set in and instead was pushing on the face of the piston keeping a constant pressure on the brakes. You can't see the pushrod without stuffing your head into the floor board. Not sure why it fell out. I popped it back in and everything is good if it falls out again I will weld a tab on the pedal assembly to prevent it.

Thanks for coming back with the answer. Like several said, it was acting like there was no pushrod freeplay, but for a different reason.

If it happened once, it will happen again.

Go ahead an put in the travel limit.

Or maybe lengthen your pushrod a tad, to eliminate some of the slack?

Originally Posted by rspears

Or maybe lengthen your pushrod a tad, to eliminate some of the slack?

I can the push rod is adjustable. There is a tiny bit of play I will adjust the play out of the push rod it might have 1/16 or a bit more of slack right now

Originally Posted by Bob o

I can the push rod is adjustable. There is a tiny bit of play I will adjust the play out of the push rod it might have 1/16 or a bit more of slack right now

If it only has 1/16" of play how did the rod come out of the cup? You need about 1/16" of play between the piston cup and the rod end to ensure that the piston comes back to let the pressure bleed back. Something sounds strange.....

Roger is right, ya need about 1/16 play, as I said B4 put a return spring on it and be done with it !!!!!!