hanging brakes

[Billybobjunky]

ok guys, i already adjusted the pushrod down to its shortest allowable distance, but my rear brakes are still hanging up. It only happens after I've applied the brakes, like they aren't releasing right, bc if I reach down and pull the brake pedal towards myself by hand, they release fine and no worries, but I don't wanna have to do that everytime after I apply the brakes. it's a new power brake set-up with discs in front and drums out back. it's a '77 front end, a '70 power brake setup and 67 rears. thanks

[Leadfoot]

I had this problem before what it was the boosters linkage was sticky all I needed to do was blast the linkage with some real good penetrating fluid, (you know on the boosters Bracket there is that leaver thing with the push rods connected to it) shoot it real good. also your brake pedal spring sounds like its @#%$ed,

if its not these your master cylinder sticky or boosters push rod is out of adjustment, or that booster is N.F.G.

[fordman]

did you remember to put on a proportioning valve from the donor truck? if not you should because that will cause the rear brakes to get the same pressure as the discs.

[QC]

You aren't using the 70 master cylinder, are you? That would be for front drums, not discs.

[Billybobjunky]

interesting point QC, so would I just get a '70 MC for disc brakes or is there something else here? thanks guys! got her registered today, bout to be street-legal!

[fordman]

actually you would want a master cylinder that match your brake booster. if the booster is a 77 then you'd want to use a 77 master cylinder. just make sure that your brake pedal is compatible with the 77 mc.

[Billybobjunky]

hmmm...i think the wd-40 fixed the problem. guess it was just sticky linkage cauz i sprayed it really good, let it all soak, and then ran quite a few trials, and it seems to all be good now.

[fordman]

thats good.

[QC]

Ford didn't have disc brakes on F-100's until 1973, so if you convert to discs you need to use a 73-78 disc brake m/cyl. A drum brake master cylinder has check valves in each fitting to hold a small residual pressure in the lines, so you don't have to pump your brakes every time you stop. A disc brake m/cyl does not have a check valve on the disc side because the calipers don't have return springs to force the fluid back. If you use a drum m/cyl with discs the front pads are going to drag and wear out quickly.