I want to thank all of you for the good ideas and help.

I have some homework to do:

Pressure test
Test brakes in reverse
Check condition of backing plates (pads)
Swap backing plates and shoes to another wheel
Check spring mounts/u-bolts
Verifiy that e-brake is properly adjusted

I'll go out and try these over the next few weeks (it's busy around here) and report back.

Thank again!

On the pressure test, it would be nice if you could do both rear wheels at the same time. They sell adapters that replace the bleeder screws. Have a helper depress the pedal as you record the readings on both sides. I would encourage doing so while appling and holding various pressures.

When swapping backing plates shoes etc, doe the drums as well.

On the e-brake MAKE SURE BOTH cables move freely

One last thought, check the run out on the axle flanges to make sure they not bent.
Good luck and keep us posted

I finally got enough energy to go out and battle the brakes in the '57 again (I've been working this for a year now and I'm getting tired of it). So here's what I did and what I discovered:

I completely removed the e-brake from the rear drums
I filled the very small groves in the three pads on the backing plates with mig welder and ground them smooth
I verified everything is put together correctly
There is no axle shaft run-out
Rear springs/u-bolts/shackles in good shape

No big change after this work and when I get back from the test drive the rear brake drums (especially the left one) are very hot but the front drums are just warm.

Now, I also did something else. I put a brake valve inline to reduce pressure to the rear brakes. When I start to close it the rear brake will not lock up as easy but the pedal starts getting pretty hard. So I put a pair of vice grips on the rear rubber brake line to remove both rear brakes from the equation. When I did that the brake pedal got VERY HARD with minimal travel and it took 30 yards to slow to stop from 25 mph. It was take me 1/4 mile to stop on the highway.

Am I fighting the wrong problem? I wondering if both front brakes are doing enough? Again, everything there is new as well...

I'm wondering if the master cylinder is plumbed correctly.

Does this have a modern, dual-circuit master cylinder or the original single outlet??

If it's a dual circuit, it almost sounds like you have the rear brakes plumbed to the front circuit, and the front brakes plumbed to the rear circuit.

This would cause the issues you're having as the front circuit has a residual pressure valve built-in that not only holds 3lbs of pressure in the line, but activates a split second AFTER the rear.

If you have the rears hooked up to the front circuit, this will cause them to both drag, but activate at the wrong time as well.

Doesn't sound as though you're fronts are doing much and they typically doe 80% or so of the braking.

I'll repeat one more time PRESSURE TEST
1st. at the master preferably, Dual master? buy two gauges, you'll need them at the wheels as well
2nd. At the front
3rd. At the rear
The numbers will confirm or eliminate the hydraulics, air, leverage ratios etc.
Not trying to be a jerk but,

Or continue to chase your tail

I know it was stated that front and rear cylinders are different, could they be swapped front to rear? I imagine the front should have a larger bore.

One would think so but not necessarily, shoe sizes, contact area, and a buttload of other things can come into play.

All origninal single pot master cylinder with one line going to all four corners.

Pressure test is on my list of to-dos I just haven't gotten the equipment (gauges/adapters) yet. I was trying everything else first. In theory it shouldn't be a pressure issue since it has one line but I've seemed to have exhausted most all other options.

The front and rear wheel cylinders cannot be swapped. They are completely different animals (wont' physically fit).

I went back to your original post and read it again and this jumped out at me:



Seems up to that point you only had one issue with the left rear brake locking up. Now you seem to have issues front and rear at all four corners. Have you discussed the issues you have now with the "professional re-builder" and asked what they think might be the issue? Have you found one of the hundreds of '55, '56 and '57 Chevy websites and Facebook pages that had to have had this issue in the past 56 years? To me the "professional re-builder" created something that was before the rebuild a single wheel lock up issue into what seems to be a nightmare or NO BRAKES! and a situation that could hurt you, someone else and your '57 BelAir. If you haven't gone back to the re-builder I would throw everything out the window and (re-) start there. If they are truly professional brake people you would hope they can help with a solution? Can they take a look at the situation or are they just a component shop or not nearby? Just thinking and typing on the keyboard.

Mike

Good thoughts.

The more I think about it the more I believe the car was this way since the beginning (at lease since I've had it). I believe there is a chance that the rear locks up so quickly because the fronts may not be doing their job well enough.

Karps Braks Service out of California did the work on the master cylinder. From what I understand they come highly recommended in the Tri-Five world. I haven't spoken with them about this yet as I struggled to see how a single pot MC could cause the issue (but I've been wrong before).

I would contact them and send them the link to this thread and they can see all of the issues you have been dealing with since the rebuild.

http://www.karpspb.com/

Mike

Having chased many a brake problem to resolution on many different vehicles I always start with an overall underside inspection, bushings, lines, hoses, frame etc. If all appears well,
# 1 Pressure check at master
#2 Pressure Check at both rear cylinders
#3 Pressure check at both fronts.|

In your case with a single reservoir master all numbers should be the same. If not find out why

Next step is linings, drums. cylinder diameter's etc.
You mentioned Power brakes, some MFR's change MC as well as wheel cylinder piston sizes to compensate for power vs non power.
keep us posted

I must've missed the part where it said the car has power brakes.

Here's something to look into.... it might be related.

A few years back, I had a '74 AMC Hornet with Power Brakes. A shotgun mechanic had been at it for the old lady owner, so many thing were done incorrectly or on the cheap. One issue I had with it from Day 1, and took me MONTHS to figure out was this: the brake pedal was mush for about half it's travel, and would accomplish diddly squat. But as soon as you'd hit that halfway point, the pedal would get a little stiffer, but you now had ALL THE BRAKES. Usually front right would lockup first. The car was virtually undriveable like that.

Anyway, after rebuilding all four corners, changing rubber and hard lines.... it still did it. So, that only left two pieces of the puzzle. A new-looking master, and the booster. I wrote off the master since it looked new! Well, the instant I removed the master, I'd found the problem. The pushrod from the power booster came out with the master!! Whoever did the master last, didn't know the difference between a power or manual master and had left the manual style pushrod locking clip in the master. This caused the pushrod to jam inside the master, not sit inside the cup in the booster like it's supposed to!

Well, after fixing that, the car had perfect brakes.

If that's possible to do on your '57, I'd suggest checking that out.