C15A brakes jamming

[harrygrey382]

The brakes are sticking on my Chev. It's not that you apply and they stick, they are on fairly well, even with the shoes backed right off and hyd. pressure released. Jacked up I can hardly rotate each wheel, and it's really sapping power - can't get into 2nd while moving (lost momentum by the time it's in gear) and won't pull top on a flat. Motor is rebuilt.

I rebuilt (honed, new rubbers, all new lines, new linings) the brakes on my C15A. Problem is that was about 12 years ago. It then sat for "a while". I know alarms bells are now going off about brakes sitting unused with fluid in them. At the time, there were so many things going on, and I was so thrilled to finally be driving it (a rolling chassis with no go pedal or seat) I didn't pay much attention to how it was getting along.

Fast forward 'till now and I'm revisiting all the work I did in the past
I've tried tightening the shoes as hard as I can then backing them off. In my mind, this is pushing the pistons back in the cylinders, then I back them off, in theory creating clearance between the shoe and drum. That is, assuming the pressure is caused by the pistons sticking out. But this doesn't help, they're still just as stiff before.

So now I'm thinking, maybe the linings are too thick or something's assembled wrong (in each wheel, unlikely). Am I missing something or is my logic correct here? I'll have to pull the drums off I know but just getting things right in my head first, and haven't had time yet either...

Pedal feels good btw

[Bruce Parker (RIP)]

I bet the wheel cylinders are 'stale' and not releasing allowing the shoes to retract. Pull a wheel and a cylinder to see what's up. If the bores are clean then clean up all four wheels and the master, re-bleed and away you go. If pitted and full of crap...you'll know what to do.

Typically it goes the other way after a long sit. You apply pressure at the pedal and the rotten seals or pitting causes a pressure loss.

[TCLARK]

Also make sure there is a bit of "play" in the brake pedal when at the top. My CMP will sometimes not let the brake lights go out because all the pressure is not released. I backed off the rod in the brake master cylinder so there was play and problem solved.

[Dave Mills]

Have you by chance overhauled your master cylinder? Maybe just maybe if you have you could have placed the fluid return washer in back the front, upside down, etc. The washer is usually a wave washer, If this little washer is in back the front it will allow the fluid out into the wheel cylinders and will not allow it to return to the reservoir tank, keeping the brakes engaged. When you say you have released the pressure is this from all 4 wheel cylinders or from the master cylinder? Just a thought as I have suffered the same problem with my own repairs, not a C15A but never the less have suffered the same problem.

[hrpearce]

Originally Posted by Dave Mills

Have you by chance overhauled your master cylinder? Maybe just maybe if you have you could have placed the fluid return washer in back the front, upside down, etc. The washer is usually a wave washer, If this little washer is in back the front it will allow the fluid out into the wheel cylinders and will not allow it to return to the reservoir tank, keeping the brakes engaged. When you say you have released the pressure is this from all 4 wheel cylinders or from the master cylinder? Just a thought as I have suffered the same problem with my own repairs, not a C15A but never the less have suffered the same problem.

I agree with Dave it seems that the master cylinder is not allowing the fluid to return.

[Richard Farrant]

Originally Posted by hrpearce

I agree with Dave it seems that the master cylinder is not allowing the fluid to return.

This can be proven easily by releasing a bleed nipple on a wheel and seeing if it will then turn, if it does not then it is a seized wheel cylinder.

[Hendrik van Oorspronk]

Originally Posted by harrygrey382

So now I'm thinking, maybe the linings are too thick or something's assembled wrong (in each wheel, unlikely). Am I missing something or is my logic correct here? I'll have to pull the drums off I know but just getting things right in my head first, and haven't had time yet either...

Pedal feels good btw

Did you adjust the bottom mountings of the shoes correct? if not they can stick to the drum.

Hendrik