mechengrkj Posted January 17, 2014 Report Share Posted January 17, 2014 (edited) Noticed a funny smell today after driving home from work and narrowed it down to the rear brakes. Jacked up the rear end and the rear brakes are locked. I eliminated the ABS a little while ago (with a Wilwood bypass line from Summit) and replaced all the brake flex lines with stainless (Techna-Fit lines). Bled the brakes until the fluid cleaned up. Replaced the master cylinder and both front calipers as well as the rear right caliper about a year ago along with the e-brake cable. The weird thing is that both rear brakes are locked. Maybe the proportioning valve is clogged? Anyone have any suggestions? UPDATE: I bled the rear brakes but no effect so I removed the proportioning valve and the downstream side gushed a bunch of fluid out. I'm guessing that is the problem? What does one do to check it without having pressure gauges etc? Also, can it be disassembled easily without ruining it? UPDATE: Opened up the proportioning valve and cleaned it all out. I wasn't sure which way the little ribbed o-ring in the bottom so I put it in so that it sat the same as the curvature of the inner wall. Cleaned all the gunk out of the end of the bolt, it was pretty dirty. Then reassembled everything. I wasn't able to find any major problems so hopefully the little bit of gunk in there will fix it. Otherwise, the only other thing I think it could be is the master cylinder (which is brand new). Edited February 7, 2014 by mechengrkj Link to comment Share on other sites More sharing options...
mechengrkj Posted January 17, 2014 Author Report Share Posted January 17, 2014 Can anyone corroborate my findings? Anyone had a problem like this before? Link to comment Share on other sites More sharing options...
ucw458 Posted January 17, 2014 Report Share Posted January 17, 2014 I haven't had that problems but the only thing I can think of are dirt in the prop valve which you cleaned and a defective stainless hose. The stainless hoses have an inner and outer liner then the braid. Sometimes the inner liner separates from the outer and plugs up the line. When that happens you can have brakes that don't work at all or brakes that stay locked up after you take your foot off the pedal. Since it's both rears I would suspect the ABS bypass line. Pull that line off and try to force compressed air through it. If it's defective it should plug up and not let air through. Link to comment Share on other sites More sharing options...
kev Posted January 17, 2014 Report Share Posted January 17, 2014 Are you sure that the lever arms for the e-brakes in your calipers aren't frozen? Link to comment Share on other sites More sharing options...
mechengrkj Posted January 17, 2014 Author Report Share Posted January 17, 2014 (edited) I haven't had that problems but the only thing I can think of are dirt in the prop valve which you cleaned and a defective stainless hose. The stainless hoses have an inner and outer liner then the braid. Sometimes the inner liner separates from the outer and plugs up the line. When that happens you can have brakes that don't work at all or brakes that stay locked up after you take your foot off the pedal. Since it's both rears I would suspect the ABS bypass line. Pull that line off and try to force compressed air through it. If it's defective it should plug up and not let air through. Good idea ucw. I'll try that. Are you sure that the lever arms for the e-brakes in your calipers aren't frozen? I doubt both of them would freeze at the same time. They were working fine before the ABS delete, plus the right side is a newly rebuilt caliper. After bleeding the pressure off the lines, I was able to put the ebrake on and stop the rotors from turning and as soon as I let off the brake they rotated again. But once you press the brakes, the rears lock up again. Thanks for the suggestion. Edited January 17, 2014 by mechengrkj Link to comment Share on other sites More sharing options...
kev Posted January 17, 2014 Report Share Posted January 17, 2014 I'm having a hard time trying to figure out how the hydrualic system could maintain pressure locking the brakes with your foot off the pedal unless your master is sticking (but that would lock up the fronts as well). My guess is still a mechanical issue. Corrosion on the pistons or the e-brake lever. They don't put enough grease on the e-brake levers when you get a rebuilt caliper. I've seen Cardone and Centric rebuilt rear calipers seize up within a few months...especially during the winter. You should be able to move the levers by hand with a little force. If they don't move easily or they move too easily with no resistance, then there is corrosion causing binding on the mechanical assembly within the caliper. There isn't much to these brakes especally with the abs removed. One line from master to prop valve, one line from prop valve to rear axle, to a T fitting, and one line each out of the T to the calipers. kev Link to comment Share on other sites More sharing options...
Edde Posted January 17, 2014 Report Share Posted January 17, 2014 It's been a long time but I am pretty sure I've heard of something like this before. It really is hard to imagine how this couldn't be pretty simple. Unless the lines are just flexing instead of having fluid pressure release. Link to comment Share on other sites More sharing options...
ucw458 Posted January 17, 2014 Report Share Posted January 17, 2014 There is also a check valve for the rear brakes. I can't remember if it's built into the ABS or not but I think it's below the booster on the firewall. If that has dirt in it the rear brakes will stick. Link to comment Share on other sites More sharing options...
mechengrkj Posted January 17, 2014 Author Report Share Posted January 17, 2014 It's been a long time but I am pretty sure I've heard of something like this before. It really is hard to imagine how this couldn't be pretty simple. Unless the lines are just flexing instead of having fluid pressure release. Yeah me too. Just undoing the lines out of the proportioning valve relieved all of the pressure on the rear calipers. There is also a check valve for the rear brakes. I can't remember if it's built into the ABS or not but I think it's below the booster on the firewall. If that has dirt in it the rear brakes will stick. I think you are referring to the proportioning valve on the firewall. That's what I removed and cleaned. Link to comment Share on other sites More sharing options...
mechengrkj Posted January 18, 2014 Author Report Share Posted January 18, 2014 Worked on the issue a bit more today. Bled the master cylinder directly to make sure that wasn't the problem and I'm able to cycle all the bubbles back into the reservoir. Hooked the bleeder hose to the downstream side of the proportioning valve and it seems to push fluid through. Hooked the bleeder hose to the tee in the rear and no fluid comes out. So either there is a problem with the proportioning valve not letting fluid through or somewhere in the line between the proportioning valve and the tee in the rear. Any ideas? I'd rather not go drop $100 on a new proportioning valve if I don't have to. Link to comment Share on other sites More sharing options...
creakyjoints Posted January 18, 2014 Report Share Posted January 18, 2014 You answered your own question. Fluid comes out of the proportioning valve. No fluid comes out of the rear t. Hooked the bleeder hose to the downstream side of the proportioning valve and it seems to push fluid through. Hooked the bleeder hose to the tee in the rear and no fluid comes out. Must be the line or the t. I know one member had a problem with the rear t on his just recently. Rust! Link to comment Share on other sites More sharing options...
mechengrkj Posted January 18, 2014 Author Report Share Posted January 18, 2014 You answered your own question. Fluid comes out of the proportioning valve. No fluid comes out of the rear t. Hooked the bleeder hose to the downstream side of the proportioning valve and it seems to push fluid through. Hooked the bleeder hose to the tee in the rear and no fluid comes out. Must be the line or the t. I know one member had a problem with the rear t on his just recently. Rust! It's not the tee because I removed it and cleaned it beforehand. I was able to slide a small allen wrench through it no problem. I even tried hooked a little hand vacuum pump up to the rear bleeder. Holds 20 inHg but still doesn't suck any fluid through. Link to comment Share on other sites More sharing options...
mistapickles Posted January 19, 2014 Report Share Posted January 19, 2014 on the back of the brake pads is a little metal pin that sticks out, if you don't position that pin in the little bow tie looking part of the piston the pad will teeter between being wedged on the rotor and letting the rotor spin. it might be a coincidence that you noticed the dragging pad after doing the delete but that happened to me. Sometimes I would get really bad gas mileage then other times I would be fine, depended on how rough the road I drove on. Link to comment Share on other sites More sharing options...
vbrad511 Posted January 20, 2014 Report Share Posted January 20, 2014 Unbolt the line coming into the T in the rear and see if you get fluid. You're on the right track, just gotta chase the obstruction down the line until you find it. Link to comment Share on other sites More sharing options...
mechengrkj Posted February 7, 2014 Author Report Share Posted February 7, 2014 UPDATE: I purchased a Wilwood adjustable rear proportioning valve and replaced the stock one. That seems to have fixed the problem. I drove around for a while tonight and didn't have any issues. Hopefully this fixed the problem for good. Thanks for all the helpful tips guys! Link to comment Share on other sites More sharing options...
importwarrior Posted February 7, 2014 Report Share Posted February 7, 2014 have a link to the wilwood unit you used? Link to comment Share on other sites More sharing options...
mechengrkj Posted February 7, 2014 Author Report Share Posted February 7, 2014 (edited) have a link to the wilwood unit you used?Sure! I used this one, but ended up having to use a bunch of adapters to make it work because we have inverted flares and not bubble flares. You'd be better off using a standard size valve (like this one) and getting adapters that convert it to metric or 3an like mine is. I adjusted the valve to be the upper limit on the split pressure from the service manual. Edit: Here are the part numbers just in case the links get broken. The one I used: Wilwood 260-12627, and the one I would use if I had to do it again: Wilwood 260-10922. Edited February 7, 2014 by mechengrkj Link to comment Share on other sites More sharing options...
importwarrior Posted February 7, 2014 Report Share Posted February 7, 2014 Thanks for the info! Link to comment Share on other sites More sharing options...
Shelby Posted February 11, 2014 Report Share Posted February 11, 2014 locking the proportioning valve is WHY us old timers always tell you to NEVER press the brake petal had when bleeding the brakes ,on most car's it's just a centering valve, if you push it to one side by over pressing the petal hard while bleeding you can lock it up , now if the valve is clean and free of dirt it will not stop fluid flow but if yours was that dirty , it was beyond repair from the start , with a valve only to the rear brakes it's a pressure reducer , making the front brakes grab slightly ahead of the rear , and yes it can pug up completely I'm sure theres 100's of good used ones out there but the trick is DO NOT push hard on the petal when bleeding the brakes ,when the petal stops ,stop pushing Link to comment Share on other sites More sharing options...
mechengrkj Posted February 11, 2014 Author Report Share Posted February 11, 2014 locking the proportioning valve is WHY us old timers always tell you to NEVER press the brake petal had when bleeding the brakes ,on most car's it's just a centering valve, if you push it to one side by over pressing the petal hard while bleeding you can lock it up , now if the valve is clean and free of dirt it will not stop fluid flow but if yours was that dirty , it was beyond repair from thestart , with a valve only to the rear brakes it's a pressure reducer , making the front brakes grabslightly ahead of the rear , and yes it can pug up completelyI'm sure theres 100's of good used ones out there but the trick is DO NOT push hard on the petal when bleeding the brakes ,when the petal stops ,stoppushing Good tip. Thanks Shelby! Link to comment Share on other sites More sharing options...
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