57 Cadillac brakes not releasing.

[Gene McCormick]

I have removed every brake drum and all 4 brakes are fine and I have a new master cylinder installed last year and brakes were
great. Now as soon I apply brakes in my garage they don't release and brake pedal sometimes barely moves. Hand brake is not on.
I can move forward a bit but in reverse almost impossible. I did install a new carb and had to disconnect vacuum hose to power
booster but it is rehooked up. Is the power booster unit ??  Is there any test to see what is causing the problem? It says in shop
manual....check vacuum cylinder lubricant level. How do you do that ?  I did unhook the vacuum line. No change.  Brakes seem to
be locked on all four wheels. Kinda like pushing down a shock and it does not return. Back to pulling off wheels again.

[dplotkin]

Gene; you have a different and if I recall properly a one year only booster/master. My 60 Electra (Delco-Morain) failed with similar symptoms, engine vacuum sucked the brakes on full, had to kill the motor to release them. On the other hand a maladjusted pedal to master pushrod can cause the brakes to drag, heat up, expand & lock up. Had that happen too, in my 62 Bonneville. Check these things, I'm betting its the booster. They are perishable items on old cars-kind of like heater cores.

Dan

[Gene McCormick]

Thanks for info. I did disconnect booster hose from manifold but nothing has changed maybe overnight brakes will release. This is a
learning feat since I have 2 57's. The super nice one may need my knowledge how to do it in future. Trust Cadillac to put distributor
at back of engine by firewall and master cylinder underneath car then later like my 71 everything got easier for us home mechanics.
Gene

[Walter Youshock]

If you haven't had the booster rebuilt, get it done.  Not to say this is the problem but it is possible.  Also, have you bled the brakes AND the booster?  How are the return springs on the shoes and the wheel cylinders?

I had the brakes on my '57 lock up and had to go through the entire system--new cylinders, rebuilt booster, shoes and springs.  This was 15 years after I had the entire system redone.

The piston in the booster:  the Shop Manual calls for Shock Absorber fluid to lubricate the piston.  The plug is on the back of the booster facing the firewall.  The only way to get at the plug is to remove the booster.  There's an easier way.  Slide the small rubber hose on the top of the booster forward and insert a small hose into the pipe that goes back to the piston.  Get a bottle of hydraulic jack oil--that's what I was told the equivalent of shock absorber fluid is--and squirt some into the hose.  It may free up the piston.  I still wouldn't trust it if it has the original booster that hasn't been redone. 

[N Kahn]

Did you replace the brake hoses? They can collapse internally, let fluid in but not let it back, you can't always tell the damage from outside.

[Gene McCormick]

All you guys are great...God bless this club and its members........I did disconnect the hose from manifold and sealed the manifold
tube. Everything returned to normal. Car has brand new brakes on all four plus new master cylinder. On a road test car stopped
with no problem. I may pull the booster and send it to a that place in Florida. I did not realize how good the manual brakes are.
Thanks again everybody I can sleep better. Gene on Vancouver Island Canada. Pix is my neighbours yard from my kitchen window.
Yes we have Palm trees here.

[dplotkin]

Did you replace the brake hoses? They can collapse internally, let fluid in but not let it back, you can't always tell the damage from outside.

I overlooked this possibility, certainly could account for it. Good point.

Dan

[Jon S]

My guess is the brake pedal push rod behind the pedal is adjusted too long.  Try shortening it about 3 to 4 turns and re-tighten the lock nut.  Bet that silves the problem.

Jon