brake caliper pressure

[ccryder2011]

i recently replaced the master cylinder and proportioning valve on my 67 f100 2wd shrt bed...it has 69-72 front brake disks installed....whats happening is when i brake everything works fine but the pressure in my driver side front caliper builds up after a stop (or two or three) and the brake drags...any ideas?

[chiggerranch69]

It could be anything from a kinked or otherwise restricted hose or line or an "O" ring for a caliper piston seal instead of a square cut seal. Make sure the are no residual pressure valves in the lines, as those would hold about 15 psi or so in that section of the system. Also check the caliper slides to see if there is binding.

[fordman]

i agree. some sort of blockage so the fluid doesnt return properly.

[ccryder2011]

i agree. some sort of blockage so the fluid doesnt return properly.

my son got me new calipers for my b-day... all set thanks.....

[FORDification]

i recently replaced the master cylinder and proportioning valve on my 67 f100 2wd shrt bed...it has 69-72 front brake disks installed....whats happening is when i brake everything works fine but the pressure in my driver side front caliper builds up after a stop (or two or three) and the brake drags...any ideas?

FYI: Ford didn't install disc brakes on the F100 until '73, so if your F100 has them, it's been converted by a previous owner with '73-up parts.

[ccryder2011]

i recently replaced the master cylinder and proportioning valve on my 67 f100 2wd shrt bed...it has 69-72 front brake disks installed....whats happening is when i brake everything works fine but the pressure in my driver side front caliper builds up after a stop (or two or three) and the brake drags...any ideas?

FYI: Ford didn't install disc brakes on the F100 until '73, so if your F100 has them, it's been converted by a previous owner with '73-up parts.

figured that out when doing pads...thanks

[hazelnut]

ive found that when people replace disc brakes they let the caliper hang by the hose and it streches the hose and it frays the inside of the hose and it cant be seen, the pressure will push through but has a hard time returning making the front brakes drag untill the pressure can bleed its self off.

[ccryder2011]

still building up pressure...replaced calipers,hoses,lines,proportioning valve,master cylinder,rear wheel cylinders,pads,shoes.....but still get pressure in the front brakes...wtf..??

[fordman]

new parts can be bad from day one. are you sure they gave you the right master cylinder? did you make sure the steel lines were clear?

[knightfire83]

Push rod between the master cyl. and brake booster not adjusted correctly?

Differential valve plugged up? Brake light functional or on?

[FORDification]

You ARE using a disc-brake master cylinder, right? Drum brake master cylinders have residual pressure valves that will cause disc brakes to drag if used together.

[ccryder2011]

THE MASTER CYLINDER I USED CAME WITH THE TRUCK NEW IN BOX...BUT I THINK IT WAS FOR A 67 WICH MEANS NO ITS NOT A DISK BREAK MASTER......THAT IS PROBABLY MY PROBLEM AS I WENT OUT FOR A CRUISE LAST NIGHT AND FOUND THAT I CAN RELIEVE THE PRESSURE RIGHT AT THE MASTER CYLINDER AND THE BRAKES ARE FINE FOR A WHILE....ANY FIXES OR DO I NEED NEW MASTER CYLINDER

[FORDification]

(Better double-check that CAPS LOCK button on your keyboard...I think it's stuck!)

Yep, it sounds like you've installed a drum-brake master cylinder, and because they come with residual pressure valves that a disc-brake master cylinder doesn't have (for the disc circuit), it's maintaining pressure in the front circuit. I'd be willing to bet that replacing the master cylinder with the proper piece will take care of your problem.

[ccryder2011]

thanks i think your right i will get new master cylinder and see whats up...sorry bout the caps lock my son used comp last...
thanks , cris

[ccryder2011]

finally got all the right parts and the brakes work like new....thanks to all that helped....!