Drivers rear locking up

[ChrisDollins]

Ok, I have a weird problem going on. Before I order an adjustable proportioning valve and throw this valve, I would like for yall to look it all over and see what you think. I did the disc conversion last summer and I don't remember it doing this. Right now the drivers side rear brake seems like the only one working. It is very grabby, but it does release when you let off. I've bled everything probably 6 times and I am getting good fluid out of the front. I adjusted the brake way in and it did better. But it would still lock up first, but it would let the fronts at least start to work. But after driving it a few times, it's back to using only that one. Thw adjuster had moved back out. Whats going on? Any pointers? Here are a few pics.

Chris

[ChrisDollins]

A little bit more info. I tried to use a c-clamp to hold the little pin into the valve, but couldn't get it to work. But I did still get a good amount of fluid out of the bleeders on the front. I checked to make sure the small surface shoe was towards the front. Can't think of anything else.

[T and S]

might have to install an adjustable proportioning valve.

[ChrisDollins]

That's pretty well where I'm at. When I deleted ABS on the '00 Z28, I went with an adjustable one. Really liked it. Only thing that has me concerned is why is it just the drivers rear and not both.

Chris

[T and S]

another thought - maybe the adjuster on the other side is not working, may be worth while to pull it apart and check.

[luvbowties]

Originally Posted by ChrisDollins

Ok, I have a weird problem going on. Before I order an adjustable proportioning valve and throw this valve, I would like for yall to look it all over and see what you think. I did the disc conversion last summer and I don't remember it doing this. Right now the drivers side rear brake seems like the only one working. It is very grabby, but it does release when you let off. I've bled everything probably 6 times and I am getting good fluid out of the front. I adjusted the brake way in and it did better. But it would still lock up first, but it would let the fronts at least start to work. But after driving it a few times, it's back to using only that one. Thw adjuster had moved back out. Whats going on? Any pointers? Here are a few pics.

Chris

You said, "But after driving it a few times, it's back to using only that one. Thw adjuster had moved back out." Sounds like driv side adjuster is working correctly. Also, sounds very much like your pass side brake is not working because it is not being adjusted along with driv side. Check adjuster on pass side. May still have to install an adjustable propor valve to reduce fluid going to rears, but you need to get both rears synchronized first.
Sam

[ChrisDollins]

Just incase anyone else has a similar problem, I did figure it out today. I had planned on putting the adjustable p-valve on yesterday, but realized I didn't have all of the fittings I needed. And the more I thought on it, the more I thought maybe the front seal on the primary piston in the master cylinder was bad. So this morning I replaced it, and that fixed it.

At first my parking brake cable has been froze up, so a friend thought that may be causing the one rear wheel to engage first. I finally got the cable loose and adjusted it to enough slack and made sure not to set it until new cable comes in. Then I had thought maybe the adjusters were causing trouble, so I pulled the automatic adjusters out and ran both adjusters almost all the way in where they wouldn't drag at all. One semi-quick stop in the gravel and it drug the drivers rear. It was like the fronts were getting nothing, but they would bleed. They just wouldn't get enough pressure before the pedal started engaging the rear brakes in the master cylinder. The pressure was being bled off back into the reservoir. The master cylinder was bought new when I did the disc brake swap like two years ago. Wasn't expecting it to be bad. I will get the rears adjusted right and the automatic adjusters back in when I put the adjustable p-valve in during winter. Crazyness.

Chris

[derail]

Just curious, when you were bleeding the brakes, did you get fluid out of the back? I know that you said the fronts bled normally. Sounds kind of like a problem I'm having.

[ChrisDollins]

I did. That's what was getting me so bad. All four bled good. After working around on the pass rear a little more, I was able to get it to lock up in the gravel along with the fronts.

Chris

[MikeN]

Originally Posted by derail

Just curious, when you were bleeding the brakes, did you get fluid out of the back? I know that you said the fronts bled normally. Sounds kind of like a problem I'm having.

If you're not getting fluid out of the rears, check that rubber flex line over the differential housing. Very common for those lines to deteriorate over time and get completely clogged up.