55.2-59 1958 Apache 38 brakes dragging all around.

[studeclunker]

Okay, I'll list it out here and hope the organization helps...
Truck: 1958 Chevy Apache 38
Problem: brakes dragging badly, heating up wheels and brake drums, all four wheels. Makes climbing hills with this venerable old six rather slow. I mean, I could almost get out and walk faster.

What the hell is going on? Is it the Master cylinder, or what?

Happens at the worst possible time, of course...

[IMG]front rt by studeclunker, on Flickr[/IMG]

[leegreen]

some ideas:

Brake pedal pivot is gummed up and not pulling back up all the way/spring is weak
Brake master is gummed up /rusted (but usually they would leak too)
All 4 wheels over adjusted
all 4 wheels have gummed up wheel cylinders
All 4 wheels have rusty brake shoe - backing plate contact areas

Does it have an old hydrovac booster under the cab somewhere? it may also be gummed up or the valve to control it is stuck

[studeclunker]

Well... the booster isn't underneath (just under there and didn't see anything like that. However the hydrovac Booster in my '66 is on top of the wheelwell inside the engine compartment. Don't recall seeing one. If I remember correctly though problems with those cause either a complete lack of assist or a complete lack of brakes at all!

Considering the build up under there though, It wouldn't surprise me if the pedal arm has something to do with it. I'm not looking forward to removing the brake drums. Oldies like these are never fun to get off.
Kinda seems odd all four seizing at the same time though.

It really is nice sliding under this thing! LOTS of room without having to get the jack out.

[dsraven]

if it has a booster I would be surprised.
first, do all the brakes seem to drag or just the rears/fronts/a certain wheel?
-when the brakes are dragging, sometimes after a run where the brakes have been used and are hot, try cracking a bleeder screw and see if there is a bunch od residual pressure in the system. this coiuld mean the system is not allowing pressure to bleed back into the reservoir when the pedal is released. if the brakes seem to be ok when cold but get worse and worse as they heat up it could be the linkage is not allowing the master cylinder to fully return to the fully released position so as the fluid expands when hot the brakes drag more
-adjust the brakes, park brake fully released and backed off first, then adjust each wheel, then adjust the park brake
-check all the steel lines for kinks or flat spots caused by mechanical damage
-check the rubber hoses for cracks, bulges, obvious leaks etc.old hoses can have internal breakdown which can make a flap of rubber on the inside which works like a 1 way valve, not allowing pressure to return to the reservoir as quickly as it should
-check the pedal and ensure it is coming all the way back to the top. there shold be some free play. the pedal arm should have a stopper that hits the firewall/floorboards on the engine side of the firewall.
-follow the linkages all the way down to the master cylinder, checking for worn pivots, binding linkage etc.
-check the rod that operates the master cylinder to ensure it has some freeplay so you can be sure the master cylinder is returning all the way. have a helper step on the brakes a few times while you watch what happens to all the linkages etc. check for a broken return spring that should return the pedal to the top every time easily
-check for worn out cab mounts or rusty cab mount sheet metal that would allow the body to move on the frame. this allows changes in the linkage so it affects the pedal/master cylinder rod free play
-check the master cylinder for leakage around the push rod which would indicate an internal problem. --check the reservoir to ensure it has clean fluid and the cap seal is in good repair.

[dsraven]

my tablet ran dry on juice so I was typing in the half dark scenario. sorry for the spelling.
also check each pivot and bellcrank for being stiff. this means undoing some lnkage so you can check each part by itself with nothing else connected to it. check for holes that should be round but are not and rod ends that should be round but are not.

[dsraven]

unless the brake system has been changed at some point I believe you would have a single circuit master cylinder, which means ALL your brakes are connected together in a single hydraulic circuit. if you need to change your master cylinder at the end of the troubleshooting phase you may want to look into a dual circuit master cylinder as they split the front and rear circuits. this is because they realised that if there is a leak or problem in ANY of the original single circuit brakes, and you have a failure due to fluid loss, then ALL your brakes go out at once. the park brake isn't really made to be used at great speeds so you run a good chance of crashing.
if the system is stock, and all 4 wheels are dragging, it seems the problem would be the master cylinder not releasing the system pressure when the brake pedal is released. thats what all the "check this check that" chat was about, to eliminate possible issues that can work together to make this happen. it is hard to do but if you are able to remove the master cylinder reservoir and look into the reservoir (with safety glasses on of course) while a helper steps on the pedal you should see a small fountain of fluid in the res when the pedal is initially stepped on. this is because when the master is fully released the piston in the bore of the cylinder goes past the little holes in the bore that allow reservoir fluid to fill the bore OR return fluid to the res after a brake application and equalize system pressure when the pedal is released. when the pedal is first pressed the piston initially starts to move fluid and since those holes are in the working area of the bore for the very first part of the pedal stroke the fluid moves back into the res rather than be pushed down the bore and out to the wheels where there is resistance. the fountain, or at least a disturbance in the res fluid, is normal. if there is no disturbance in the fluid it is an indicator that the master cylinder is not fully returning, so those little holes don't get to refill the bore OR return fluid to the reservoir should that be required (like when the brake fluid gets hot, expands, and can cause a pressure build up in the system). another good thing to do is hold a constant pressure on the brake pedal and check to ensure the pedal stays at the same height throughout. hold for a minute and see if the pedal drops at all. this indicates an internal leak in the master cylinder and usually is accompanied by a small external leak where the pushrod enters the master cylinder. if the rubber dust boot is deteriorated or all gooey it could indicate a fluid leak there.
dunno if that explanation helps or not. hope so. getting the brakes to drag, then cracking a bleeder screw is the easiest way to see if the system is holding pressure but it is a good idea to check all the other points as well, just to be sure it is all good before you spend money on somethimg that isn't needed possibly.

[mr48chev]

The guys gave some good advice but here are a few things.

1. reach in with your hand and push the pedal down and make sure that you have a slight noticeable free play before you start pushing on the piston in the master cylinder.

2. a return spring on the pedal is a must have with no excuses item.

3. I was taught 62 years ago to tighten up drum brakes until you couldn't turn the wheel by hand and back them off ELEVEN clicks. I've done hundreds if not thousands of brake jobs that way and taught a lot of students to do it that way. It works well, end of story.

I won't second guess old parts that might stick and worn backing plates that the shoes might hang up on the little rub pads that they slide on. Some times old worn shoes slide over those ridges and you put new shoes on and the sharp edges hang up.

[dsraven]

does the truck do this all the time or just after it has been driven for a bit and the brakes have been warmed up?
take it for a spin to warm things up
jack up truck and block so all wheels are off the ground
check if the wheels spin easily or if the brakes are holding and check for any grinding noises etc, like a shoe is rubbing on the drum
if they are holding then first check the pedal to see if it is returned completely so the pedal arm rubber bumper is against the firewall. next check to ensure the master cylinder has some freeplay on the pushrod. there is a return spring down there that can get weak and the weight of the pedal can be enough to overcome the spring, especially if everything is gummed up under there. it's why i asked about the pedal returning fully
the bushing where the pedal arm goes through the floor can also be a tight spot if it is worn and has moved around some. this is especially bad when the cab mounts have become worn out or the body has rusted and crumbed where the cab mounts fit up. some body movement can cause the pedal arm to bind where it goes through the floor
step on the brake pedal a few times. you should have a nice firm pedal that is sitting at the normal height when the brakes are applied, like not too far down towards the floor. keep the pedal pushed for a minute and ensure the pedal doesn't slowly keep dropping towards the floor. you shouldn't hear any strange clunking noises when you do this and if you do it could be the backing plates are worn where the shoes have rubbed against them and the shoes now get stuck in the divot creaked. when the brakes are activated they force the shoes out of those grooves and this causes a clunk. it also makes brake adjustment impossible sometimes. release the brakes now and recheck to ensure you don't have a tight wheel. if the brakes are binding then first check to ensure the pedal is acftually all the way back at the top against the rubber bumper, if good then try loosening a bleeder screw to see if the system is holding pressure. remember that a drum brake system is supposed to hold a couple pounds pressure to keep the wheel cylinder cups pressed against the cylinders and sealed. worse case scenario take a front wheel and drum off and check to see what you have.
let us know what you find, since you have our curiousity going. some pics would be great.