Technical Hard pedal, manual drum brakes

Yes. It’s all the way out. No free play

 

You need some free play, back it out till you have at least an eighth

 

no free play means you will get locked up brakes.

Get some free play in there, and you won't need to mess with the hoses.

 

The pedal is not restricted from swinging freely. The mc rod is out all the way. The pedal just fastens to it.

 

I have $5.00 that says other wise.

 

You know Matt, you remind me of my kid. I love the boy. But he calls me up say's Dad I have a problem what do you think, then argues why that isn't it.
Now Squirrel, Jim...he's like my buddy Kevin. Difference is, when I call him up I just listen and say thanks.

So to be clear, that rod should rattle against the master cylinder piston. So, with the pedal pulled up by the spring, or held up, then if you removed the rod from the pedal, would it be loose enough to rattle? Just a bit before pushing on the piston. Cause if not, that's the problem.

 

"Observed rear brakes were warm, and the fronts were hot to the touch."
"once I roll and stop repeatedly the pedal travel decreases and get super hard."

Pretty standard symptoms of lack of free play between the pushrod and master cylinder, as pointed out in several posts.

If there is actual feelable free play, then look at the master for problems with the rebuilding or kit used.

These are the only things that usually cause a problems on all four brakes as described.

Probably more likely than all the brake hoses failing at the same time, any time that I have had a hose problem it has been related to the brake served by the hose, and did not effect the other three.

 

^^ THIS ^^
Go like a few turns shorter on the rod and try it. The other thing when the pedal gets better after a pump indicates the brake shoes need adjustment.

On bad brake hoses, usually 1 is bad and the car pulls towards the working side. I've never seen 2 bad hoses at the same time.

 

This is out of the Oldsmobile 1966 service manual, Pontiac will be the same.

STANDARD BRAKE PEDAL ADJUSTMENT (52, 54, 56 & 58 Series)

An incorrectly adjusted brake pedal can hold the master cylinder piston from fully returning to its released position, which will result in brake drag or lock-up.

1. Remove the pedal return spring and the master cylinder push- rod clevis pin.

2. Turn back floor mat and check pedal height (from floor pan to top of pedal pad). If di- mension is not 7-15/16" + 1/8", loosen lock- nut and adjust stop screw. (Fig. 5-6) Tighten locknut and recheck adjustment.

3. To adjust the master cylinder push-rod, lightly push the master cylinder push-rod until it contacts the hydraulic piston.

4. Loosen locknut and adjust push-rod until clevis pin can be freely installed into the brake pedal, then shorten push-rod one turn for proper free play.

5. Tighten locknut and connect push- rod to brake pedal.

 

You said the parts were the same for the M/C but did you check the depth of the pushrod hole.

 

This is one of those "pull your hair out" posts. Not because the answer isn't available, but because the OP won't listen to it.

First thing to check is the push rod. It is free to fix, will take two minutes to adjust, and provide instant satisfaction.

Unless you bought an OEM rebuild kit, the possibility that the new internals are a couple hairs off is pretty good. Those hairs will make a difference in that pushrod adjustment.

 

If you look into the master cylinder reservoir, you should see two ports. A large one and a very small one. When you release the brakes, the piston and lip seal must move far enough back to uncover the small port called the compensating port. If you shine a bright light into the reservoir you should see that the port is clear. That is, you should be able to see to the bottom of the cylinder bore. It is a bit hard to see with fluid in the reservoir. What most of the people are telling you is that the master cylinder piston isn't going far enough back on brake release to uncover the compensating port. That is your current problem that you must fix first. You might have bad flex hoses, but your current problem is due to no free play in the pedal.

 

As stated earlier.
Since yesterday I have crossed over to the push rod problem.
While seeing more hoses go bad in my time. There was one case of push rod pressure.
Realizing that the failures were due to endless bumps and turns, the NOS parts may well be compromised by age.
They should not however fail on the test run.
I should never come on so strong, again.

 

Both front hoses failing at the same time? I’m not betting on that either, but they will get replaced with new ones just because it’s the smart thing to do.

All this advice is good. I added some pictures to help weed out anything suspect.

Pulled the MC off this morning to see if anything was incorrect or mismatched comparing the factory guts to the kit guts. Right away I noticed the stop plate was flipped. That’s about 3/16” of displacement. So that should correct the hard pedal. I put it on that way when I installed the pushrod and plate assembly a few years ago. That’s on me for F’ing that up. Along with the general filth and the missing valve seat from the factory, it was a good decision rebuild it.

Next I compared old and new parts.

The new piston is 0.030” longer, it has a full length relief for a power brake rod and the piston ports have a check valve plate over them. Thin spring steel. So I gained 3/16” but lost 0.030”. And the push rod doesn’t seat in a ball and socket way. So the kit is wrong.

It’s a Napa 234 (2029). Not correct for this application. So more research on that. It needs to be exactly the same. I don’t know why they’d add a check valve to the piston ports.

On my car you can adjust the pedal height to whatever is comfortable as long as the piston hits the stop plate and the pedal is not hitting the bracket preventing the pistons to full return position.

Thanks again for all the great info. I learned a lot more than I bargained for.

For all of you that we’re betting on the push rod as the culprit, you win.

 

If you are cracking the line at the master cylinder to relieve the pressure it is not a brake hose issue. check that you have play in the push rod attached to the pedal if the piston is not returning all the way back it will keep building pressure in the lines like when riding the brake pedal.

 

Wrench 97 he found the issue in the comment above yours.

 

Test drive #2 complete. Brakes work good.