The self adjuster is supposed to engage when, you go in reverse and hit the break that's when the puck up the slack... The way you st them for the first times after doing break work its to set the drums just pads just snug then drive the truck in reverse a and hit the breaks a few times b the adjustment will set the right tension

 

Sorry that last message was butchered so much my smart phone and is aren't getting along today

 

Not quite, you run the adjusters out until the wheel locks, then back off until they barely scrub. Then you back up and hit brakes sharply a few times to even the adjusters out.

 

I don't think it's the self adjusters, i agree with the first theory of the push rod being too long (not adjusted properly).

 

Aren't the adjusters specific to each side with one having left hand threads? Mixing them up could cause some ill effects. Just a thought.

 

Yes they are, if they're swapped left to right the shoes will retract rather than expand every time the adjusters are activated.

 

Exactly. I've decided that whatever weirdness I see with the adjuster, they are not my problem. The first responders to this message all said "GO LOOK AT THE MC". Time to heed their advice. This is a hydraulic problem, not an adjuster problem.

Thanks for bearing with me on this. It is nice to have a place to gripe with people who understand.

 

Nlareau, this thread below is from a Corvair forum, but it seems to mirror your problem to a tee, it may be worth a read...

REAR SELF ADJUSTING BRAKES OVERACHIEVING

 

Thanks. Yep, I'm pulling the MC and checking the rod length tonight. I still have the old one, install the new one without checking the length.

It does build up more and more pressure before the problem occurs.

 

Dollars to donuts that's your issue, if so, at least it's an easy fix.

 

one thing that could happen. (happen to me) if you replace your brake switch and do not set it up right. it will prevent the pedal from coming back all the way. always leaving a little bit of pressure on your break. which eventually get hot, expand and seize.

and yes i switch 3 different proportional valve, I found out by accident my boot got stuck in the brake pedal and while i yanked my foot back, I snapped the plactic of the switch, and Ta da, brake were fine.

just a tought.

 

Uhhh, I did have to replace the brake switch... I broke the old one when I was mucking around with putting the rebuilt MC in...

Now I have two things to check.

 

OK, MC was OK. Pushrod was correct length (it was the exact same as what I found in it originally).

I used air to blow out each brake line. Blew brake cleaner through each line. Yes, I know brake cleaner is bad for brake fluid. Ran brake fluid back through each line and then blew it out with air again. Yes, the lines were dirty but no huge chunks of anything came out.

Pulled each wheel cylinder. The fluid in each was a little dirty and one had a little rust on one piston. Polished it out, cleaned them up, put them back.

Pulled the proportioning valve. Blew it out with air and used a fine pick to poke around for gunk. I did find a little gunk.

Bench bled the MC.

Put it all back together and now I am back to weak brakes instead of brakes locking up.

I have ordered all new hydraulic hoses (saw lots of cracking rubber on the outsides) and ordered 25' of 3/16 steel line (with fittings) to replace all the lines.

At this point I just have a bad feeling about the lines. 35 years of twisting, turning, and stuff and I just don't trust them.

As is normal in restoring one of these trucks, I got cheap early in the process of restoring it and am paying triple for it now. Should have just bit the bullet and replaced it all when I had it down to the frame.

 

As is the case with 99% of my problems with this truck, if I had just listened to what the "old timers" were telling me 2 years ago (that and I need to quit being a cheap SOB), I'd have been fine.

Brake lines. I finally replaced all the old brake lines. Started at the back and worked my way to the front section by section. No one section seemed to make any difference (much), but by the time I replaced the last line from the MC to the proportioning valve things were substantially improved.

So the answer to my question of "what do I need to do to get some decent brakes to the rear?" is: REPLACE IT ALL. 40 year old brake parts just don't work well.

 

Ha well that's the way it goes sometimes I suppose. Glad to hear you got some good breaking power!