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proportioning valve

jfabert

jfabert

1/2 ton status
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Dec 1, 2004
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Location
South Ogden, Utah
I am sick of working on my brakes.:mad: I can’t figure out why the rear does not work worth a damn, neither can the shops I have taken it to. I am thinking about ripping out the stocker proportioning valve and installing an adjustable. Will I have any problems with my rig still having drum brakes on the back and can I hurt them but letting more pressure go to them? I have replaced every thing in the brake system but that and have had no luck. I am going to start towing a trailer soon and would love to have functioning brakes for it. Thanx for the help.
 
Re-hash for us what the symptoms are, you've done, and what you've changed.
What is "everything"?
Do you get fluid to the rear when you bleed the brakes?
Is the warning light shuttle pin centered in the combo valve?
 
I have changed the master cylinder 2x(1st one out of my other truck that had no brake problems and the snd new), passanger caliper, pads, shoes, wheel cylinders, all the springs in the drims, the e-brake hardware in the drims, the proportioning valve 2x, both used, one off my other truck and the 2nd off a juck yard truck. got fluid out the back when blead. I even had the truck runnign and my wife standing on the brakes and I jacked up one rear wheel and could turn the whell by hand. Not easly but it would turn. it seams like every time I work on them they get worse. The shops told me it is the master cylinder but it was replaced 2x with good ones. I use to be able to lock up the rear with the e-brake while driving but now it wont even do that. My buddy had the same problems with his k5 with 35's and never figured it out. my 82 k10 never had brake problems and it was a junker. That was the ONLY thing that worked on it. My K5 is an 87 with 35x12.50x15 stock 10 bolts other than gears and a limmited slip in the rear.

*edit*
Im pritty sure that the pin is sentered, but how do you re-center it. The brake light is not lit. I was tole by a shop to basicaly stomp the pettal to the floor a couple of times.
 
jfabert said:
I was told by a shop to basically stomp the petal to the floor a couple of times.
Click to expand...
Don't do this unless you feel like damaging the boot in the MC.

The first time I replaced the brake shoes on my rear I couldn't get a firm petal either. Turns out I didn't have them adjusted correctly. A simple turn of the star wheel to tighten the shoes up gave me brakes again.
 
I would try to blow compressed air through the lines. Could be a small blockage. I guess its at least worth a try. Better than throwing more money at it.
 
It does sound that they aren't adjusted correctly. Also, if the shoe doesn't come in full contact with the drum, it can hamper effective bleeding of the wheel cylinder.

I would adjust the star adjuster out until the shoes can have full contact with the drum. Not tight, but full contact. Then re-bleed both rears. Good luck.
 
I agree, try the rear shoe adjustment first.

If that doesn't help the one thing I didn't see listed as replaced are the brake hoses. Start with the rear one. Go with new. Don't mess with putting on a used one as it may or may not have the same problem.
 
I have adjusted the rears many times. They shops tryed that also. I was thinking I may have a clog also. Those were going to be the next things I was going to do, replace the lines and see if I had a clog. Probaly going to go with the braded stainless lines if I can get a good price on a set.
 
It sounds like you've done a lot, but may help to just start over at the beginning. Is the brake light hooked up and functioning? That will tell you if the proportioning (actually "combo" is correct term) valve is working and if you've got issues front to rear. It will even show a failed master cylinder, but you still have to FIND the problem.

Adjusting the star wheel was mentioned, in my experience I do it with the drum off, until I can JUST barely slide it back on.

An axle I bought the PO had put the front shoes on one side, and the rears on the other. To say it braked poorly is an understatement. Not only that, some of the brake hardware was installed incorrectly which made proper adjustment impossible.

If your ebrake won't lock them up, you've either got two separate issues going on, or something entirely different happening...the ebrake is completely separate of the hydraulic portion of the braking system, as long as the cable forces the pads "out", it works. That could be as simple as the cable needs to be tightened (very common) or again, back to brake hardware issues.
 
dyeager535 said:
It sounds like you've done a lot, but may help to just start over at the beginning. Is the brake light hooked up and functioning? That will tell you if the proportioning (actually "combo" is correct term) valve is working and if you've got issues front to rear. It will even show a failed master cylinder, but you still have to FIND the problem.

Adjusting the star wheel was mentioned, in my experience I do it with the drum off, until I can JUST barely slide it back on.

An axle I bought the PO had put the front shoes on one side, and the rears on the other. To say it braked poorly is an understatement. Not only that, some of the brake hardware was installed incorrectly which made proper adjustment impossible.

If your ebrake won't lock them up, you've either got two separate issues going on, or something entirely different happening...the ebrake is completely separate of the hydraulic portion of the braking system, as long as the cable forces the pads "out", it works. That could be as simple as the cable needs to be tightened (very common) or again, back to brake hardware issues.
Click to expand...
Yes, the brake light is working, cause when I blead the brakes I didnt hold in the button and it blobked off the rear and the light turned on. Got it re centered and it went back off. Could they not work that good if I put the shoes on backwards? Like the front on the rear and the rear on the front? I took pics before I took them apart to replace everything and put them back together the same way.
 
If your ebrake won't lock them up, you've either got two separate issues going on, or something entirely different happening...the ebrake is completely separate of the hydraulic portion of the braking system, as long as the cable forces the pads "out", it works. That could be as simple as the cable needs to be tightened (very common) or again, back to brake hardware issues.[/quote]


Absolutely, I would be money that this is the same problem. There is only one problem in the brake system that can dissable the ebrake and the hydraulic brake at the same time. There is to much clearance between the shoes and the drums (adjustment). You just have to find out why. Either something is assembled wrong in the rear shoes or they simply aren't adjusted properly.
 
JEBSR said:
If your ebrake won't lock them up, you've either got two separate issues going on, or something entirely different happening...the ebrake is completely separate of the hydraulic portion of the braking system, as long as the cable forces the pads "out", it works. That could be as simple as the cable needs to be tightened (very common) or again, back to brake hardware issues.
Click to expand...


Absolutely, I would be money that this is the same problem. There is only one problem in the brake system that can dissable the ebrake and the hydraulic brake at the same time. There is to much clearance between the shoes and the drums (adjustment). You just have to find out why. Either something is assembled wrong in the rear shoes or they simply aren't adjusted properly.[/quote]

Maybe I should get the drums turned then. When I adjust them I do it to were I can barley get the drum back on. They do have a little bit of a lip on the inner edge of them. Doesnt the adjuster push them back out though when you are in reverse and you put on the brakes?
 
Not unless they are adjusted snugly to begin with. That just keeps them in adjustment. There's a small slug on the outer edge of the drum you need to pop out, then adjust the star wheel from there.
 
jfabert said:
Maybe I should get the drums turned then. When I adjust them I do it to were I can barley get the drum back on. They do have a little bit of a lip on the inner edge of them. Doesnt the adjuster push them back out though when you are in reverse and you put on the brakes?
Click to expand...


If they are right to begin with the auto adjusters do work, but in my oppinion most only halfass work then. But yes if you do have a big enough lip then it could cause you to think they are tight when in actuality they are not. Do like the last post said and pull the rubber plug out of the backing plate (if equiped) and with the hub fully seated adjust the shoes untill they come to a point where you can barely if at all turn the wheel and then back off till you just have a slight drag. That should make a big differance.
 
JEBSR said:
If they are right to begin with the auto adjusters do work, but in my oppinion most only halfass work then. But yes if you do have a big enough lip then it could cause you to think they are tight when in actuality they are not. Do like the last post said and pull the rubber plug out of the backing plate (if equiped) and with the hub fully seated adjust the shoes untill they come to a point where you can barely if at all turn the wheel and then back off till you just have a slight drag. That should make a big differance.
Click to expand...

Mine does not have the rubber plug. It does look like there is a peice on it were I can punch it out for access to the adjuster. is this hard to do and will it be ok with out a plug?
 
That's what that slug is for. Just punch it out and adjust it. No big deal if you don't cover it. I think some people put a plug in there to keep dirt/mud/water out of there. You could probably use some silicone if you wanted.
 
spearchucker said:
That's what that slug is for. Just punch it out and adjust it. No big deal if you don't cover it. I think some people put a plug in there to keep dirt/mud/water out of there. You could probably use some silicone if you wanted.
Click to expand...


yep yep yep. Autozone also has the dust plugs in the help section.
 
thanx for all the help!! I wont be able to work on it for a while because of work but maybe next week I can give it a shot. Thank you again!!
 
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