Any Idea On Brake Problem???

I have a model a sedan z'ed 12 in front and 16 in the rear....i have all new parts front to rear.....master cylinder is on the..frame .bench bled master cylinder...have residual valves and proportion valve in system......disk front-drum rear..the problem is soft pedal and the calipers keep sticking...i have repalced the master cylinder once and the calipers twice.....i see to many cars woth the same st-up that aren't haveing problems...any ideas???

 

Soft pedal:

Master cylinder size too small
Pedal ratio insufficient, should be 6 or 8:1
Air in lines, possibly calipers or wheel cylinders mounted upside down (bleeders need to be at the top)
Bad brake hoses


Reason for sticky brakes:

Bad brake hoses
Too much residual pressure on the calipers or cylinders
Master cylinder pushrod too long not allowing the piston to return fully
No pedal return spring and a heavy pedal keeping pressure on the master
goofy brackets causing the calipers to drag
grooved backing plates causing the shoes to stick against the drums


That should get you started

 

Are your rear drums adjusted way out? If not, they should be...

 

where did the calipers come from??? seen too many rebuilt calipers from the auto parts store that have been rebuilt soooo many times the pistons cock in them and hang up.

 

what master cylinder?
what calipers?
what wheel cylinders/drums?

sometimes it matters, sometimes not, but it's more info we have to go on.

 

thanks .....thats a start.......reidual valve are only used because the calipers are above the master cylinder???becuse 2 of my friends have store bought 32 frames and they have no residual valves and they work fine.......

 

all the brake stuff is from speedway..the calipers and rotors are from major parts store.....it has a 9 inch ford rear and volare rotors with chevy calipers....all new steel lines and the 18 inch braided steel line in front.......

 

The discs should not have any residual pressure in the system. The square cut oring seal is what retracts the piston, and if there is residual pressure in the line it can't.

 

Give fergonboysinc a shout. I heard these cats were killer on brake stuff>>>>.

 

I had similar symptoms on my coupe. Drove me nuts for quite some time. Eventually replaced the 10 lb residual check valve for the rear brakes, and fixed it.

Your results may vary.