Brakes getting hot after rear brake overhaul

[jrusher]

Did some searching came up with a few checks to make but wandering what else I could be missing

1965 c10 original 4 drum set up single pot resi, had a rear wheel cylinder let go so I installed new shoes, brake hardware and new wheel cylinders on back, drums looked okay but didnt measure need to get a bigger mic or caliper to confirm I.D. Also replaced one section of line to the right rear cylinder.. Didnt do fronts as im swapping in discs in a couple weeks.
Set adjusters till i got slight drag, one side is adjusted out quite abit , bleed all cylinders down many times, e brake is also unhooked.
After driving a short while the brake pedal goes rock hard and the brakes slowly lock up and get hot, the rear ones only
- so i bleed them down again got some air outa front and same thing after driving awhile pedal goes hard and rear locks up
- so i pulled drums and slowly pumped brakes to see if the cylinders will extend out an retract and they wouldnt retract so air lock maybe? I cant see any damaged or bad lines brakes worked perfect before .So i bleed all 4 cyl again round and round , brakes work perfect on jack stands then same thing after driving for 10-15 min stop and go they slowly lock up ? This time all 4 wheels are locking up and getting hot.
- not sure what to try next ? I dont think theres air in system as ive bleed them many times ? Fluid doesnt seem to returning to resi maybe a bad line up front or the section going to the back T at diff ? Maybe the one rear drum is oversized so much that the wheel cylinder is over extended and wont retract? Its just weird that i never had issues before i changed out the rear shoes, cylinders etc. Ive never had issues before when putting new cylinders on and overhauling brakes, change parts and bleed them down and go

[TJ's Chevy]

Anything done to the master cylinder?

[jrusher]

Originally Posted by TJ's Chevy

Anything done to the master cylinder?

No havent touched it just added fluid as needed. I dont see a high level line or mark on it so just been keeping it topped right up pretty much

[TJ's Chevy]

I wonder if the master cylinder is locking up, mine used to stick a little and you could feel the brakes lock a bit.

[jrusher]

Originally Posted by TJ's Chevy

I wonder if the master cylinder is locking up, mine used to stick a little and you could feel the brakes lock a bit.

Ya could be.. Something to clean and check

[CRUZN66]

I would change the flex hose by the rear differential they sometimes look fine from the outside however they deteriorate on the inside and don't let the fluid flow properly. Besides they're not very expensive either.

Rope

[jrusher]

Originally Posted by CRUZN66

I would change the flex hose by the rear differential they sometimes look fine from the outside however they deteriorate on the inside and don't let the fluid flow properly. Besides they're not very expensive either.

Rope

Ya i'll try source one out at napa line is old original needs to be changed

[chevy_mike]

Yep, I would replace the flex line too. I have seen this happen before myself.

[vince1]

I don't know how a bad rear flex hose could also affect the fronts but worth a try.

Got the adjusters in right? Spring in place with the E brake cable to keep the emergency levers back?

['63GENIII]

Originally Posted by vince1

I don't know how a bad rear flex hose could also affect the fronts but worth a try.

Got the adjusters in right? Spring in place with the E brake cable to keep the emergency levers back?

OP says rear brakes are heating after slowly locking up.

Rubber flex line. The insides come apart and act like a 1 way valve. I've had it happen several times especially to original hoses after lifting a truck.

New hoses are never a bad thing unless they are made off shore.

[grubsster]

I agree with the rear brake hose collapsing/plugged. Happened to mine but I couldn't get any fluid to bleed out. I would also check the master cylinder as TJ mentioned, especially if you have upgraded to a dual master cylinder.

[jayoldschool]

My rear hose plugged when I bled after my MC swap. Cheap and easy to change, do it.

[padresag]

Originally Posted by vince1

I don't know how a bad rear flex hose could also affect the fronts but worth a try.

Got the adjusters in right? Spring in place with the E brake cable to keep the emergency levers back?

you did ask and you got a decent reply. the hose collapses under pressure and then creates a vacuum type scenario and holds the fluid in the cyl leaving the brakes to not release. if you park it for a bit , it will slowly leak down or change the hose and return to normal
ron

[jrusher]

Yup and thats exactly whats happening after she sits for abit the brakes free up again.. Getting new hose tonight. I'll report back soon. Thx for the replies

[vince1]

Yeah, I've seen the collapsing brake hose thing happen on two cars, a Ford Tempo and a Mercedes 450. I questioned it here because I thought he wrote that the fronts were also getting hot and I couldn't see the connection to a back hose failure. Agreed, best bet to first change the hose.

[jrusher]

Well i replaced the rear brake hose and after driving for abit brakes slowly locked up same as before. Going to have to check master cylinder next. Dont really wanna replace anything else as im installing new master and discs up front and power steering

[Brad54]

I did this exact thing.

And it presented EXACTLY as you describe--heat, rock-hard pedal, etc.

You put the shoes on backwards. The trailing shoe is in front, and the front shoe is at the rear of the drum.
Swap them, and the problem will be solved.

The front shoe (as installed now) is dragging and generating heat.
That heat is going into the brake fluid, causing it to heat and expand. Hence the hard pedal.

-Brad

[jrusher]

Originally Posted by Brad54

I did this exact thing.

And it presented EXACTLY as you describe--heat, rock-hard pedal, etc.

You put the shoes on backwards. The trailing shoe is in front, and the front shoe is at the rear of the drum.
Swap them, and the problem will be solved.

The front shoe (as installed now) is dragging and generating heat.
That heat is going into the brake fluid, causing it to heat and expand. Hence the hard pedal.

-Brad

Shoes are on correct, front smaller length shoe (secondary) on front rear longer (primary) shoe is on rear

[vince1]

What do you mean by E brake disconnected? Are the levers attached to the shoes and what prevents them from coming on?

[jrusher]

Originally Posted by vince1

What do you mean by E brake disconnected? Are the levers attached to the shoes and what prevents them from coming on?

levers are attached to shoes, cable is disconnected up in the cab at handle

[jrusher]

Originally Posted by jrusher

levers are attached to shoes, cable is disconnected up in the cab at handle

All four brakes are locking up after i drive for 10 min or so

[grubsster]

I've been thinking about this issue for a while now. Since it is a hydraulic system what happens to the fluid as it expands while getting hot from use? I'm asking because I'm really not sure. Is there a check valve that allows fluid to go back in the master as it gets hot and expands? I'm thinking the problem is there at the master. As the fluid expands it has no where to go. That is the only common factor for all four wheels to lock up I think. But I'm no brake expert...

[Captainfab]

Is this a manual brake or power brake system?

[jrusher]

Manual all drum , all stock set up , brakes worked perfect before swapping rear cylinders

Originally Posted by Captainfab

Is this a manual brake or power brake system?

[chevylookin]

You should: Open the top of the MC and get someone to pump the brakes and visually confirm that fluid is coming back into the MC when pedal is depressed. It should shoot up like a fountain after a hard press. Also, you need to take the rear wheels and drums back off and just do a visual confirmation. Are you ABSOLUTELY sure you reinstalled the springs right? Are they new or old springs? If new, are you sure they are the right size/ length? Did one of the old springs break after reinstalling the drum? Are you absolutely sure you put the the corresponding long and short shoe in the right position- front/back? It is even possible that one of the pistons in the one of the cylinders has wobble-logged itself inside the chamber on one of the wheels. When you go driving before they lock up, are you getting even braking? What does it smell like? Smells like tires and asbestos on fire? Then, youre gonna have to open everything up again. Disconnect the rear flex line at the brake cylinder side and get your friend to pump it and visually confirm juice is coming out. Then, do the same procedure at each rear wheel with the cylinders off. When you have these phantom problems, you have no choice but to start doing the aggravating, elementary and time consuming trouble shooting methods once all the simple checks have uncovered ???'s. I had a 71 Longhorn do a 360 on the 22 freeway down here going 70 mph one time because I had uneven braking that I just wrote off as no big deal. After that, and a new pair of underwear, I ripped that whole thing apart and found... a logged piston in the right rear cylinder. I am a firm believer in if you replace one wheel cylinder, you replace them all. I have replaced one before, came out the next day to see a puddle of brake fluid coming from the opposite wheel because the weak cylinder goes afterwards. But you say you are replacing the front system soon. If the I.D. on the inside of the drums is a little different from side to side, no big deal. The system will compensate for that but if the surfaces are scored, cracked or wobbley, you will definitely feel it in the pedal with pulses and kick backs. Stop scratching your head and open everything up again!