Alright I have put all new brakes on it. (Yes I searched and it's a 1989 chevy c1500 for thoes who will ask). That includes master cylinder, and wheel cylinders, shoes, drums, pads, calipers, steel, and rubber lines, and one new rotor (right side).. And we've bled and bled the lines and don't get any more air. It doesn't seem like the rear brakes want to grab like they should and it wants to put to the left pretty hard. I think it may be the old rotor is warped a little. I do have rear brakes and they're adjusted as tight as they can be without dragging to hard but it just doesn't stop like i think it should... The pedel isn't that soft and it's past the gas pedel before it starts breaking. I'm about sick of working on breaks..

 

Does your combo valve have a push button to bleed the rears? Did you bench bleed the MC?

 

Yes we bench bled it. And what/where is the combo valve?

 

Follow the lines from the MC to a block where all the lines hook up. That's it. Should be on the dr. side frame rail under the MC or hanging off the mc/booster with a bracket. Look if there's a **** on it that you can depress. Could be covered by a little cap.

 

If it's what I'm thinking of there is just a regular bleeder on top of it. And we did bleed it.

 

There's no bleeder on your combo valve/distribution block. There's a brake waring light switch on it. Check if there's a valve on the front that you can depress to bleed the rears

 

Okay I see what you're talking about.. now what do I do with it?

 

Depress it, keep it like that and then bleed the rears

 

Do I have to stick something in the hole?.. And do I have to have someone hold it in?

 

No there's a clip type tool that you can slip over the round grooved end that will keep the plunger depressed but you can keep it pressed yourself. If you use a vac brake bleeder you will most likely not need to depress it since you're not pressurizing 1 circuit as you do with pushing the pedal and you will not displace the differential pressure plunger

 

Most likely the new rotor on the right front isn't pulling it's weight when stopping. Hence the pull to the left. Until the pads are bedded in and the rotors broken in (coated with pad material), there will be an unbalanced braking condition.

Which may or may not fully correct it self after some miles. Should have done both front rotors together.

RBob.

 

I know but that was $80.00 i could have and did spend on new lines. i think i am going to replace it anyway

 

Where mite one find one of these fancy tools??

 

Do a search on ebay, combination valve bleeding tool. There are several on there from Kent Moore.

 

Alright thanks.. I'll give all this a shot and get back to you.

 

Disconnect your rear ABS also, you'll get much better brake pressure. I disconnected mine 20 years ago and never looked back. They have a tendency of releasing with a scary lag in response making the pedal sink.

 

How do you do that exactly? I didn't know they even had ABS

 

Don't disconnet the rear wheel antilock sytem, fix the problem correctly. He is correct thought that the antilock is probably causing the problem.

So you have a pull to the left and a low brake pedal, correct??
The pull left is probably in the front brakes if it's pulling that hard, rears don't usually cause a super hard pull. If both rears are even and clean and everything installed correctly on the rear, then I would check the isolation dump valve also know as RWAL dump valve. you can bypass this valve and if the pedal returns to normal, then it is the dump valve....the valve leaks internally and bleeds off rear brake pressure. The valve is located under the master cylinder and is very common to fail.
THe pull could be a sticking caliper or bad brake line in the front, would be my guess. hope that helps.

 

Hell what do I know, I have only owned a 1989 chev 1500 for 22 years and drive it daily. Yeah take his advice, don't disconnect it, he's and expert.

later

 

If it pulls really hard it's usually the front brakes causing this

 

Okay guys I understand the front brake problem and I'm pretty sure I know what to do to fix it. I just threw that in there just in case I was way off and there was some other big problem. It's the rear brakes i can't figure out. I can't figure out how the pedal is so soft with everything being brand new and tight. And just so we're clear when I say brand new I mean I've had everything on it for a couple months now and bled it a few times making sure everything is air-less and broken in.

Now about the ABS system. As I said I didn't know it had one as I've never felt them kick in. I'm assuming that would be the thing under the MC with the bleeder on top of it? And I will brobebly by-pass it to see if that is the problem and if it is and a new one in't that expensive I will probably replace it. Maybe.

 

How did I know you were going to argue with me, lol. I agreed with you that it is the problem area. Whatever.
If you just disconnect the electrical portion of it, the dump valve will still leak. If you bypass the dump valve completly, if that's what you were saying, then yes that will work.

 

You won't feel the abs kick in because it's rear wheel only, and it doesn't use a solenoid the pulse the brakes like new abs systems, on yours if it detects wheel lockup then it releases pressure to unlock the wheels....or "dumps" the excess pressure.

 

So I can just take and rout a line around it right?

 

Just unplug it electrically.

 

yes take a line and route around the controller right below the master cylinder....run new brake fluid lines. And also do unplug the unit so the computer isn't still running it. You can try just unplugging it and see what it does, but since the brake fluid is still traveling through it and leaking through that dump valve, I don't think just unplugging it will solve the low pedal issue, the valve will still continue to leak rear brake fluid off decreasing the rear braking pressure. that is the easiest of course, to just unplug it, and you can always try it first to see if it works.

 

Alright.. I got a rotor today and the fittings I think I need to by-pass it if I need to. so I'll get back to you. but the shop is full and it's to damn cold outside to be working on anything out there. So I don't know when I'll get to work on it.

 

Haha.. well it's not going to matter for a while it looks like... I popped the hood to check out the ABS thing and just out of habit I pulled the dipstick...... she's full of water.

 

nice

 

Yeah I'm thinking head or head gasket.. I just put intake gaskets on it. but it's old and probably about wore out I don't know what we'll do with it...

 

Seems to me I feel the pedal pulsate when my abs kicks in in my (1-ton) pickup, which happens a lot when I drive the thing empty in the rain. correct me if I'm wrong, but i think they dropped that weight-sensing proportioning valve deal when they put on the rear only abs. the rear brakes are tuned for a full load, so you can hardly use the fronts if they are allowed to lock up the way they want to. if those rears are pulsing you can lay into the pedal and stop the truck a lot shorter than if they're skidding.
I wouldnt disconnect my abs except for diagnostic purposes, and I wouldn't suggest someone else disconnect their abs unless I wanted to get sued.

 

I have an 83 stepside without the ABS stuff on the rears. It was a suicide machine in the wet with the rears locking up sometimes and no weight on it. The biggest improvement I made was installing a Stewart LRB (klock resistant brake valve), I think they are now marketed/made by DPI. Check it out, may be a good addition.

 

Disconnect the crap and just put some better braking coefficiant brake pads (Porterfield RS-4 ofrsomething equivilant- I persomnally love Stillen metal Matrix pads) on the fronts to up the front brake coefficent power and balance the bias of the rear drums without ABS.

This is the last I care to post on this so I will not be checking back into here. It is now beating a dead horse. The crappy ABS rear setup on these 88 and 89 systems were junk and deems to be known for releasing the rear brakes unexpectedly over bumps and dips and the entire truck lunging forward very nervously with a small time frame of brake failure till they recaught.

I WOULD UNHOOK THE CRAP

Thats my experience and my two cents on this subject. Do as you wish with this info, but I can guarantee you what I say has facts.