Front brakes not releasing

[Tunis]

Hello,

Finally took my car out for some test drives. I'm running power assisted Willwood disc brakes in front and stock drums in the rear. When I brake heavily, the fronts won't release. Are there any adjustments to be made to the brake system? The brakes weren't new when purchased, could it be some corrosion or something that makes them bind up? Under low brake force, the disc's release.

Any suggestions?

Thanks!

Per

[Chryco Psycho]

First open the bleeders to see if they release , if they do then the problem is upstream in the proportioning valve or master if the pushrod is adjusted too long the master may not allow fluid to return for example   , if not the problem is in the caliper itself .

[Ramman]

As stated. Open the bleeder screws and see if they release. If so, it's fairly common for the inside of the flexible brake hoses to break down. They act as a one way check valve.

[RUNCHARGER]

A 4 wheel drum brake master cylinder could cause that as well.

[chargerdon]

My 74 Challenger with front power disc brakes developed that problem on the drivers side wheel.   

Releasing the bleeder did in fact release the brake.   The problem was simple...the hose had broken inside and causing it to hold pressure.   Replaced the hose and the problem was gone.    Oh, and no you cant see the problem on the hose...but with it off it allow air to go thru it from my air compressor fitting.   So, i knew it was bad.      Had the same problem happen many years ago on a 84 Celebrity old car.   

[Tunis]

Thank you all for the replies!

I also think it's the brake hose now. I could bleed of the pressure with the bleeder valve and it would allow the wheel to spin.

Next question, where can I find the part number for the brake hoses? Or does anyone know the fitting sizes that I need to find some hoses?
I tried to find a hose, but there are to many varieties out there..

Thank you so much!

[Dmod1974]

Are BOTH wheels failing to release pressure?  Highly unlikely that both hoses are failed the same way at the same time.

I suspect your master cylinder is not returning all the way back and keeping the ports blocked due to a booster or pedal adjustment issue.  The master cylinder has to return all the way back and seat against the snap ring.  It should not be preloaded whatsoever.

[chargerdon]

Brake hoses are avail at just about every part store.   I think for my Challenger i bought it at an Advance auto parts.   Only differences are front / rear and Disc/drum.   Rockauto has for around $8 plus shipping.

[Tunis]

I will try again and see if they both lock up. If I remember correctly, they both locked up. What adjustments can I make on the master cylinder or pedal the get it to return completely? The brakes don't do anything during the first half of the pedal travel, if that is a clue. Vacuum is hooked up and I'm at 0.6 bar(a) (17.6 inHg) pressure at idle.

Thanks!
Per

[Chryco Psycho]

Simply if you loosen the master cyl from the booster & there is pressure pushing the master forward the pushrod is too long , there should be no pressure with the master tight but the pushrod should just touch the piston in the master

[Tunis]

Fixed the problem. Thanks for the replies!

[moreparts]

What did it turn out to be?