need some help on my brakes..

first off, i have searched but really didn't come up with what i need to know..
on my 50, i've got an after market swinging/firewall mounted brake and master cylinder, front discs and rear drums. when i got it all plumbed the brake pedal is at the top of it's travel, i press on the brakes and it's like they do not release. i put a 10 lb residual valve in the rear line and none in the front.. my question is do i need a residual valve with my firewall mounted master cylinder since it's above the calipers/drums?? what else could i be doing wrong?? is the residual valve holding the presure and not releasing it??

 

Do you have any 'freeplay' at the pedal ? check pushrod length and ensure piston in master is returning all the way back .

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#1-You do need the 10 lb. residual valve for your early rear drum brakes.
#2-The pedal requires a separate return spring to bring it back to rest. The internal master cylinder springs only return the pistons, and are not strong enough or designed to return linkage and pedal.
Make sure you have about a 1/16th" push rod clearance to the master when the pedal is fully returned.

 

thanks for the responses... i don't have a return spring on the pedal right now. i'll be checking that out today. i hope it's just a matter of adjustment and adding a spring to straighten this out..

 

10 rear 2lb front

 

Most factory master cylinders designed for disc/drum brakes have a redisual pressure valve built in. Might want to check that.

 

I suspect the problem is that the MC pushrod is too long - which does not allow the piston to uncover the compensating port - keeping pressure in the system.Looking down into the master cylinder, you should see a little squirt from the hole at the botton when pedal is released. Like said before, you need about 1/16 pedal free travel - and a pedal return spring. I guess I wouldn't worry about residual valves with your high MC location, but lots of differing opinions here - but would not cause this problem.

 

There's no need for a 2 lb residual to discs when the master is higher than the calipers.

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I agree with Fms427. Compensating port. But with some M/C-aftermarket brake assys with a bit looseness in the push rod you may have no brake until the pedal is depressed way down. If push rod is adjustable , adjust it longer until the M/C piston retacts just enough to clear the comp. port. It will improve the brake a lot. On my 41 ford with a ECI M/C the pedal went to about 3" from the froor before any pedal. Was real scary. ECI said that's normal with an old Ford pedal. After I did the above I have brakes after 1" of travel.