Technical help for breaking system on 54 chevy belair

Hello gentlemen, i'm new to the site and really could use some help, before i go out in my garage, start my car and asphyxiate myself. first let me tell you, i've been a motorcycle and car guy for years. and have done all my own work, ever since i took apart my first mini bike (mini taco) and put it back together, because i wanted to paint it red. done plenty of motor swaps, tranny swaps, and brakes on all types of cars/trucks. this one has got me baffled................

I purchased a 54 belair from a neighbor, the car had been in his garage for for 22 years. my first question was, does it run? "it did when i parked it" no problem i said. gave him the cash, he and some of the kids on the street helped push it two house's away into my garage. got to work on it right away. after three days and a few hundred bucks, it fired and ran like a champ. took it about nine miles to a friends house and the back left brake locked up. realizing i completely ignored that part of the car, i went through the brakes and replaced the drums, shoes, springs and wheel cylinders. also bearings and seals. after nine more miles, the same thing happened. back to garage, took all apart and put back together, drove about thirty miles, went to pull into my driveway , again, this time both left front and left rear. took apart ,put back together again, after about thirty miles they froze up again. here are two symptoms #1- after cooling down for about a hour, it will roll again #2- the pedal goes almost to floor after sitting all night, then gets more and more pedal the more you drive and right before it locks up, there is too much pedal, no play at all. has anyone ever ran into this ??? PLEASE HELP ME !!!

 

First thing I would look at is the free play between the master cylinder push rod and piston along with making sure the pedal return spring is doing it's job.

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What about the master cylinder?

 

Did you rebuild the wheel cylinders and master cylinder? Replace the flex brake lines ? Clean out the main brake lines? Sounds like one or all of these may be the problem area. The car has been sitting for a long time.

 

Master cylinder sounds like it shit the bed
Check your push rod clearance and that the pedal spring is working
Did you replace the flex lines? They can collapse internally, but still look good on the outside

Post some pics, I love 49-54 chevies !

 

[Q

I just assumed it was good.

 

Yes all that you mentioned was done except for master just assumed it was good

 

yes replaced flex lines

will check spring, and clearance.

 

how much play should there be between the push rod and piston, or should there be any?

 

Assume nothing where brakes are concerned. I purchased a rebuild kit from O'reillys believe it or not. After an overnight soak in some stiff cleaner, I honed the cylinder out and rebuilt it. This was on a 1951 Chevy. A rebuilt one is kinda pricey. Give it a try. Rebuild kit was about $15 bucks I think. Easy peasy!

 

will post pics asap

 

I dont know about a 54 Chevy but on the 51 there was a little access panel in the drivers side wheel well that I unbolted and the master cylinder slid right out. Didnt even have to take the pedal arms off of it.

 

Will do. there's a O'reillys down the street. thanks for the help guys will let you all know what happens

 

They had to order it but had it in a day.

 

Get a shop manual. It helps with stuff like this.
I had a similar problem with a '50 Ford Coupe.
Untitled by Travis Brown, on Flickr

On my car the brakes would get harder and harder. The drums would heat up. The brake lights would come on after parking the car. (pressure switch)
It was the by-pass port as illustrated above.
This is an illustration showing typical master cylinder design from 1951. All brands are similar.

In my car I had a bad casting. It was a replacement cylinder but the by pass port was spotted but never drilled through. I was able to correct this without removing the cylinder from the car.

Likely rust or dirt had plugged that hole. If there is trash or build up on the piston, it may be pushing the cup forward covering the port. If the master spring is too weak, the cylinder too rusty, the piston may not return enough to open the port.

All you may need to do is clean the Master cylinder...
Depending on condition you may also have to....
Rebuild the Master....
or
Replace the Master...

The symptoms of increasingly excessive pressure as you drive point to the by pass port or another master cylinder problem.

Other things to check are the backing plates, namely the pads on the plates the shoe slides on. Worn backing plates have a groove worn in the pad the shoes slides on. If excessively worn, the backing plates can grab a shoe and not allow it to retract fully.

If the plates are lightly worn, you may can lightly touch them up with a file. If severely worn , the plates can be reconditioned by brazing or welding up the groove and grinding and filing the pads
back down to spec.

These cars have Bendix brakes. They are a very good and reliable design but....it has to be perfect before it sees the road again as in no loss of pedal overnight. These old systems give you warnings that you must heed. If they are not perfect, they need repair. Also the parking/emergency brake needs/has to be in good working order.

 

That's a nice car . But without brakes it won't be. Worth every nickel a new master costs, it sat for the same 22 years , so that's where I would start. Would have replaced it at the same time as all the rest

 

Old cars, I put them on 4 jack stands and drop everything off the car that is brake related. Take pictures first!!

Take it down to the backing plates, chuck the flex hoses, chuck the master unless a kit can be found for it. New or rebuild the wheel cylinders, check the drums for size, have them cut. Look over the hard lines carefully, replace any that are so-so or bad. Squirt carb cleaner into the lines and blow them out until what comes out is clean.

Check the rear axle seals for signs of leakage, make the call to replace them while the car is apart. Go over the ball bearings for the front, now is the time to convert to rollers.

Clean and paint the backing plates, assemble with new springs, clean up all the hardware, use the right assembly white lube on any metal-to-metal contact surfaces. Get the manual, it will help with the brake adjustments and master set up.

 

Hello bobss396, I did all that you mentioned above, with the exception of cleaning out the lines. I replaced all of them, cleaning out junction blocks as well. Complete assembly was taken down to backing plates, and yes, they were worn. They got a good filing before they were painted. I applied a thin coat of anti seize to the raised areas. In hindsight, i should have rebuilt m c. I don't know what i was thinking, or what the reasoning was for not doing so at the time

at the time. Thanks to all you good people and your info. My guess is, that after i rebuild the master, the problem will be solved.

 

sorry bout that please read reply to bobss396

 

F-one, thanks so much for taking your time to explain. Im sure its the master based on the information. you are a true gentleman. again thank you

 

ill have to check on that today

 

you are correct sir

 

When it locks up crack a bleeder and see if it frees up. If replacing master cylinder there one for powerglide or standard.

 

Looks to have been covered in F-ONE's manual picture; but about 1/2" pedal movement before the push rod contacts the master cylinder piston.
Your description of the brakes dragging and the pedal getting hard while driving and then backing off after sitting is is typically a result of the master cylinder not fully returning. In a car that had been previously working; but has been sitting a long time, it can be from the pedal pivot getting stiff, push rod to pedal pivot getting stiff, or the master cylinder piston not fully returning do to corrosion. You can check most of the mechanical end of this by feel, you would have to pull back the boot on the master cylinder to visually check piston return.
You also mentioned a low pedal; with everything new, maybe try a different adjustment procedure.
Tighten the star wheels until the wheel won't turn, then tighten them further as much as you can, then back the star wheel off until there is only a slight drag. This way seems to get everything in the right place. The top anchor pins provide an eccentric adjustment to center the shoes; but if you didn't do anything with them, they should be OK.

 

I also believe the brake hydraulic system should be completely gone through. Master, wheel cylinders, flex hoses and even hard lines if they look at all suspect. Brake fluid will absorb moisture from the atmosphere and cause corrosion. Every old car I've tried to resurrect has had fluid contamination issues, usually severe rust and heavy pitting.

 

I'd have to agree that the return port between the piston and the reservoir was being closed off by the piston while you drove. For what ever reason remains to be seen as it could be no or a weak return spring, crud in the cylinder causing it to hang up after being pushed or the pushrod not being adjusted right. My bet is on return spring or crud. After pushing the pedal a number of times it is acting just like it would when you are pumping the pedal to bleed the brakes.
On adjusting the brakes I was taught to tighten the adjuster wheel until you couldn't turn the tire by hand and then back it off 11 clicks back in 1962. That has worked for me on hundreds if not a couple thousand brake jobs over the past 50 something year as I did brakes daily as my job for a number of years.

 

The residual valve can also fail to let the fluid return.

 

All has been torn down and rebuilt. Replaced with new parts except mc. Heading down to purchase rebuild kit now
thanx

 

Thank you very much for the good information. i will pass it on to my boy, so that the knowledge bloodline does not die.