Rear brakes glazed?
 

I am slowly getting my 72 set up for 100% street. Figured I would pull the drums before I put the rally wheels on. Had a leaking brake cylinder. I changed the rear brake cylinders and rear flex hose to the rear. Installed new rear shoes. I did a brake check on the dirt farm road and the back wheels will not lock up. I jacked rear of the car up and put in gear and have to press the pedal as hard as I can to stop the wheels from spinning. Also with e brake applied I can get it to move with a little throttle.
I never had a line lock when I raced this car. Just held the brakes. I never noticed this brake problem when I was racing it. But never looked for it. I have been racing it on and off this way for 20 years, With very little street driving.
Do you think the rear drums are glazed?
Tomorrow I will pull the drums and inspect them closely. I will try and sand them to see it helps.

Sounds like the rears aren't bled completely. I use this system and it works great. https://www.summitracing.com/parts/m...+5d4c9cc121695

Make sure the shoes are set up so there is some light drag on the drums. Also check for the shoe with the largest friction lining is installed to the rear. Are the adjusters free of crud so they can turn, good luck.

There's a good chance your new linings have a much harder braking material than your old ones. Before wasting a lot of money reinstall your old ones if they have decent lining material left. If that fixes the problem find a set of shoes with softer material.

That is the same brake bleeder that I am using, Yes longer shoe is on the back and adjusters are working. I sanded the drums with 80 grit to get the shine off, no improvement. I took the steel braided flex line off and reinstalled the rubber, no improvement. I reinstalled the braided line to get rid of the 50 year old rubber one.
Tonight I took the back of the proportioning valve apart and cleaned it. I did have some crud in it. I will bleed the brakes and bleed them again tomorrow.

Not wanting to sound like a Beavis....

Have the drums been machined? How new are they?

The new wheel cylinders, how do they compare to the old ones as far as the size of the bore/ piston diameter? If they are not the same or correct size that would effect the braking power.

Have no idea on how old the drums are. They have been cut at one point, They measure 9.530. There are no ridges on them.

It could have been acting like this for years. Just never checked.

When I put 4 wheel discs on the race car I kept locking up the brakes on a dirt road and adjusted the proportioning valve until al 4 wheels locked up and backed it off a hair. Thats what gave me the idea to check the 72's brakes.

Drums are usually designated, good to use up to .060 over.
So yours are still good.

A lot of brand new shoes don't require cores anymore, I often wonder
if they're shaped correctly? Not many places offer re-arcing anymore.
Scribble on 'em with a marker, see what kind of contact they make? :Ithink:

Have everything back together and flushed front brake fluid also. It just seems to take a lot of pedal pressure to stop, To lock up the front on the street at 20mph I have to really stand on the brake pedal.
I checked to brake booster by pumping the brakes and while holding it down start the car, Pedal drops about an inch. So I think that is good.
I am thinking it might be the proportioning valve or master cylinder. I will change the proportioning valve when I put the new stock engine in.

What else would cause a lot of pedal effort?

Maybe I am just use to my truck and race car having touchy brakes.

Two possibilities:
- a particularly hard shoe material on the new shoes. Great for long life, but lousy as far as 'bite' is concerned.
- more likely......oversize drums [ have been machined ] & shoes have NOT been radius ground to suit the drums. Result is that the new shoes only have a small contact area on the drums....& poor braking.

Have 2 new Bendix finned rear drums in Pa. if in need.