The Stovebolt Site Forums The Shop Area Driveline 3100 chevy break problems

Hello all,

I'm looking for some help in regards to a breaking problem we've come across. It is an original early 3100 chevy pick-up with the manual gear box. It has the original not modified brakes. And the brake master cylinder was overhauled few years ago, when this problem started occurring. Also all slave cylinders in the drum brakes are new. This hasn't solved the problem.

The problem:

After some longer (20 miles or so) distances the break pedal gets really hard, and the brake pads start touching the drum, uptill the point where they break so much, its wiser to stop. (Also considering the heat build-up) After waiting and having everything cooled down, it's back to normal.

Anyone ever had this problem?
Anyone care to help me figure this one out?

Thx, Regards
Bart

It sounds like the hydraulic fluid is heating up. There shouldn't be any heat source near the brake lines, but I would inspect them front to back to make sure. If, for example, the hydraulic lines are too close to the exhaust pipe, that could explain the problem.

How are you adjusting the brake shoes - what procedure?

What year truck - it makes a difference in how they are adjusted?

You might simply have the brake shoes adjusted too tight/close to the drums.

Thanks Paul, I will check the lines and heat sources. And come back.

Thanks Tim, I will ask my dad in law the exact year it is. I thought a 49-er... But I'll check. Than I will adjust the shoes myselve to make sure they don't touch. However a mechanic at a local garage tried to tackle the problem, so the shoes should be adjusted oke. But I'll redo it anyway.

Might this be a master cylinder problem, because that would be the only mechanical unit that actually could generate presure?

Thanks again so far, to be continued!!
:-)

From your description, it sounds like the brake shoes are not backing off after using them for a little while. This is usually a heat related problem. There are one of two causes that I'm aware of for heat related problems. Both are the result of the lines or equipment being too close to a heat source.

Since the master cylinder is mounted on the frame, it's unlikely that there is a heat source close enough to it to cause a problem. Also it has a fairly thick body so it would take a significant heat source to cause the fluid to heat up.

OTOH, a line could be misrouted and be too close to an exhaust pipe.

The other source of heat is brakes. If, as Tim points out, the brakes are adjusted too close to the drums so that they're dragging, they will build up heat over time. That heat buildup could cause the hydraulic fluid to heat up, and in a closed system (which is what a brake system is) that will cause pressure buildup.

The brakes should be adjusted until the shoes touch the drums enough to cause them to drag slightly. Then they should be backed off about 10 clicks. As they wear, they have to be readjusted.

When you're adjusting them, you should tap on the drum with a hammer to cause the brake shoes to equalize inside the drum so that the clearance is the same for all 360 degrees.

From the Shop Manuals:

1949 and earlier 1/2 ton (Huck style brakes): After tightening to a slight drag, back off 5 clicks.

1951 and later 1/2 ton (Bendix style brakes): After tightening shoes to a slight drag, back off 14 clicks/notches.

http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0513.htm

By 1954, the advice on 1/2 ton Bendix brakes was back off no more than 7 notches.

I got a break problem too, mine are too short I prefer 15 minute breaks rather than 10. I also have a problem seeing the wrong spelling for BRAKES, BRAKE, BRAKE PEDAL, BRAKE SHOES ETC. Sorry I guess I just see way too much of it on the old net.

It could be the compensating port is being covered because the linkage is pushing the piston in the mastercylinder over it. Or the mastercylinder was assembled incorrectly. Or if it was sleeved maybe it was not redrilled? Just some things to look at.

Opps just noticed your from another country, sorry about the brake thing, even the ones here don't get it right.

Huck brakes can be finicky after servicing (drums turned, new shoes). They are fixed by pins at the bottom and don't move around as much as Bendix do. When you turn the drums and install new shoes, they may not share the same radius and need time to wear until they match up. I start out having the shoes set a little snug and let them machine themselves to a good fit. This can cause some heating but it usually isn't permanent as the high portion of the shoes wear to conform to the radius of the drums. You can expect to adjust them again sooner than what would be normal. Huck brakes aren't self adjusting like modern brakes, so regularly scheduled adjustments are required.

"I also have a problem seeing the wrong spelling for . . "

Do you also have a problem with people correcting your grammar/spelling? I see way too much of that on the net:

that should be "correctly" (not "is not working correct[/i]")

that should be "you are" or "you're" (not "Yes dear [i]your[/i] right")

that should be "Are" there any rust out (not: "Is" there any rust outs)

that should be "to" boot (not "too" boot)

Let's stop here. None of us are perfect; and,[i] "people in glass houses, . . . "

However, when people never use any punctuation (and never separate different/multiple sentences), those are real communication problems.

Awl write wee gnu what he mint.

Nice my dumb phone always auto corrects my spelling and if i dont catch it it looks like i have drain bramage sometimes.

Thanks again Paul!

I'll see if I have time on monday to check and adjust the brakes, after checking the exact year she was build. :-)

Truckrolet, sorry for not using your language propperly, :-), I'll do my best! Thanks for your tips, I'm not sure how to check these things without overhauling all cylinders....

Great to get so much helpfull tips!!
Thanks again,
Bart

One thing that has not been mentioned is the return springs. If these are new disregard. However, if they are old they could be fatigued and weaken as they heat up. If the brake hardware hasn't been changed I would replace all of the springs. Otherwise I would look at the brake lines picking up heat. I would look at the main line that crosses from the drivers side to passenger side. On my 49 the line follows the cross member and is "housed" or shielded by said cross member. However, is someone replumbed the line and ran it farther forward near the radiator, that could be a problem.

just a shot in the dark but are the leading and trailing shoes the same size? Could they have been reversed? I remember this happening to me as a kid on my 65 c-10 when they got hot they pretty well locked up if I recall...

The leading and the trailing shoes??? I'm a Chevy novice, could you explain that a bit more??

I think the springs were renewed if I remember correctly!

Bacchus, the "leading" [front] and "trailing" [back] shoes on each wheel are different [on later Bendix brakes anyway], see your shop manual Tim linked above .... something I don't see mentioned, have you replaced the rubber hoses front and back? they can deteriorate inside, resulting in collapsing when warmed and preventing easy flowback of the fluid

Bill