brakes sticking...thoughts?

[sactoC10]

Picked up this GREAT 1971 1/2 ton 350 long bed from the son of its original owner three weeks ago. The truck was well maintained and taken care of by dad, but basically it has sat for the last few years.

Put dropped spindles on it over the weekend and while in there decided I might as well put in new brake pads. I found it odd that as one set went in, the fluid level in the reservoir did rise. Instead, the cylinder for the opposite side got pushed way out. It was then impossible to push the cylinder back in, even with a C-clamp. I ended up having to remove fluid from the bleeder in order to back the cylinder in to install the new pads.

Now since I've had the truck the brake light has remained ON. replacing the pads, adding fluid, etc... seemed to get the light back OFF. Yet, my test drive last night was not good. Brakes still stuck, had to mash the gas to get it moving, which happened once before.

Any ideas? Master cylinder shot? Something else? HELP!!! I gotta drive my truck!

[smokekiki]

Did you hold the button in on the front of the prop valve when bleeding the brakes?Also new master cylinders are pretty cheap.Depending on how the brake system was maintained it might be a good idea to change it and flush the fluid.I just put new master,calipers and wheel cylinders on my suburban.Made a big difference!

[sactoC10]

No... I was playing around with that button though! Maybe you can explain to me it's purpose. What does it do? I was pushing it in when I added some fluid. I'm thinking a new master cylinder, once I've exhausted the cheaper options.

Thanks again.

[smokekiki]

It centers the piston inside the prop valve.The piston off center makes your brake light come on.You can make a tool out of metal bent at 90 degrees and cut a slot to fit behind the bolt that holds the prop valve.Slide the tool in till the button is pushed in then tighten the nut.Then bleed the brakes.Make sure the caliper bolts are clean and lubed so the caliper is free to slide.

[sactoC10]

Thanks, that is good info. Yup, when I took the front spindles off and put the new ones on, along with new upper ball joints...I cleaned EVERYTHING including the caliper bolts. Scrubbed them with a brush and WD40 so they were smooth.

OK, so fabricate the tool. Slide the tool in then tighten the outside (toward the front) nut? What if the light is already off? It is off now, so wouldn't that mean the piston is in the correct place?

And once that is done bleed the brakes. OK, got it.

Another question (which makes me think the master cylinder has croaked). My reservoir seems to seep (not drip, not leak, just seep) fluid. I replaced the gasket, but that did not resolve the problem.

It seems as though my master cyclinder is simply working only one way. Maybe bleeding the brakes will make a difference.

Thanks again.

go to this site to see a picture of my project
< http://www.classicperform.com/PhotoG...mage-008-L.htm >

[smokekiki]

You need to use that tool anytime you bleed the brakes.I got a new mater cylinder at autozone.I think it was around $24 with lifetime warranty.

[TooMany2count]

check you front rubber brake hoses, it could be collapsing inside..........joe

[sactoC10]

Check them how? Have someone press the pedal and lay underneath looking? You are talking about each rubber section on each side next to the coil spring, right?

[TooMany2count]

have some one put pressure on the pedal like your bleeding it & open the bleeder, if it comes out slowwwwwwwwww then its collapsing inside and has made a rubber flap inside & is like a one way valve. Some fuild may come out or none may. Also could be crud in the wheel cylinders causing a blockage. They say when you push calipors & wheel cylinders back in you should crack the bleeder to remove all the old cruddy fuild in them, that way it doesnt contaminate the system.....joe

[sactoC10]

More good info. When I cracked open the one side to get the pads into place, the fluid that came out was dark and cruddy. I did not do anything with the opposite side. What you are describing sounds like the problem though. I'll give that a try too.

[TooMany2count]

hope it helps you....joe

[sactoC10]

MUCH BETTER!

Here's the update. Got my "mighty vac" bleeder tool (something you simply must have) into position and sucked the nasty fluid out of the system.

I had two different levels of gunk that came out of there, the dark brown dirty fluid and then the thick crud that settled to the bottom of the clear plastic reservoir, along with some nice little particles of who knows what.

So I do think my master cylinder is working fine, but I do want to replace the rubber brake lines. Does any parts store sell those, or should I get them from a specialty distributor?

Thanks for all the input.
JT

[TooMany2count]

any good parts house should carry them........joe

[sactoC10]

OK.

As we know thus far, I've put in new pads, flushed my old fluid and just bought new front brake lines, and installed them Saturday. Took it for a test drive and all was well for about 5-6 miles this time, then the sticking started again.

Got home, opened up the hood to peek at the master cyclinder and this time fluid had squirted out of it. So, took a trip to the parts store yesterday, bought new master cylinder and installed it but I never comepleted bleeding the lines.

Any help with this? Advice? I have a vacuum pump and I've done it before, but have never replaced a master cylinder before. What do I need to know...especially that proportioning valve trick/tool info.

I think I am doing something wrong, or forgetting something.

JT in Sacto