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| Rear Brake Pressure Issue | |
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| Tweet Topic Started: Oct 8 2012, 02:48 PM (1,296 Views) | |
| jherman93 | Oct 8 2012, 02:48 PM Post #1 |
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I've got a 1992 Geo Metro XFi that I picked up recently. It was having a rear brake issue where the shoes were sticking after e-brake usage. I took the drums off, took everything apart, cleaned and relubricated everything. Now the e-brakes loosen up just like they're supposed to. Problem is, I went to bleed the brakes because I imagine it probably hadn't been done in a while and found that I'm not getting any pressure to the right rear drum. I used the two-person technique that I've done before and my helper said the pedal was not getting any firmer at all. It just felt like pushing the brake pedal down while the car is running, each push was just as easy as the last. With my assistant holding the pedal as I opened the bleeder valve, nothing would come out of the valve and the pedal's feel did not change at all. I continued trying to bleed the other wheels starting with the left rear and it wasn't easy due to lack of pressure buildup in the whole system, but that particular corner still did get pressure like it should and it bled the old fluid out without too much hassle. When I got to the fronts, the front left worked just fine as well, but the bleeder valve was stuck on the front right. I tried everything to get it off and was only destroying the valve so I gave up before I broke it off and lost all fluid. I'm going to get a new caliper for the front and disconnect the lines throughout the system to figure out why the right rear's not getting pressure this weekend, but for now, can any experts on here help me with regards to what you think it might be? Or, let me know what all is in the brake system as I am new to metros and don't know what's all included as a whole. All I could see is the master cylinder which has 3 lines going to the passenger side of the engine bay on the firewall which I imagine is some sort of brake force distributor, then 4 lines out of that going to their respective wheels. My theory is that since the master cylinder has only one line for the back two brakes and since the back left is working, the master cylinder must not be faulty. It's either the "brake force distributor", the lines from it to the right rear, or the brake piston in the right rear. Is there anything else in the brake system that I'm missing? Is my theory correct? What is the proper name for the "brake force distributor", if that even is what that thing is? As an aside, what's the correct pattern to bleed the brakes? I know it's longest brake lines to shortest brake lines so since the "brake force distributor" is on the passenger side of the engine bay, I think it should be LR, RR, LF, RF. Is that correct? Thank you to all who have spent the time to read through this and thank you again to any who can give any insight to my predicament! |
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| snowfish | Oct 8 2012, 04:58 PM Post #2 |
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Basic GearHead
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Before condemning the proportioning valve,![]() I'd take the bleeders out and clean them. Probably pretty muddy. If you had brakes before, trying to bleed may have lodged crud in the bleeders. If that's the case, the entire system is muddy up too. Much, much bleeding & flushing May cure the situation.Worse case is you install new wheel cylinders & lines to the flex hoses. The flex hoses are a possible culprit as well. It's a pretty basic system. Sound like you've go a pretty good working knowledge of it. Correct bleeding sequence? I try to start with the rear farthest away from the master cylinder. Curb side. Then work closer from there. |
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| clarkdw | Oct 8 2012, 05:42 PM Post #3 |
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It is a split diagonal system. LR and RF on one circuit and RR and LF on the other circuit. The two rear brakes have no interconnection. Does the RR brake work? Jack it up, hold the pedal down and see if you can turn the wheel. If the brake works then the blockage is right in the bleeder or the wheel cylinder. If the brake doesn't work then check for loss of pressure elsewhere. |
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| jherman93 | Oct 8 2012, 08:10 PM Post #4 |
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Thanks for your help guys. The right rear does not in fact even press against the drum. No pressure is getting to it at all because even with the pedal pressed (and the left rear drum stopped) the right side drum still spins freely. I know the bleeder isn't clogged because I took the drum back off and squeezed the piston inward and some fluid came out the valve (open of course), but the piston didn't come back out even when the pedal was pressed. Also, since the front left bled just fine and works just fine, it's gotta be the right rear only with the problem. Brake experts: can you explain how it's a cross-over brake system if there are only 3 lines coming out of the master cylinder? I understand the reason for pairing up opposite corners, but am not sure how that works. Is it like one of the front two lines in the master cylinder being LF/RR and the other is RF/LR, with the third being a return line from the proportioning valve? |
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| t3ragtop | Oct 8 2012, 08:27 PM Post #5 |
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Turbo3 and Twincam Tweaker
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the rubber hoses are always suspect. i've found more of them swelled closed on the rear of metros than almost any other car. nobody ever changes them (except me) and they cause more problems on old brakes than any other part. it could also be a bad wheel cylinder. both of those parts are cheap. when i want to do a brake job and be done with it, i just replace everything - wheel cylinders, hardware, shoes, drums, hoses on the rear and calipers, pads, hardware, rotors, and hoses on the front. you can replace nearly every brake part on a metro for under $100 (not counting the master cylinder which adds another $50-$60.) i've never had a proportioning valve go bad. |
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| clarkdw | Oct 9 2012, 12:40 AM Post #6 |
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LF and RR come out of the front of the master. The LF comes directly from the master to the caliper. The RR goes to the proportioning valve. The other two, LR and RF are fed by a single line from the rear of the master and that line also goes to the proportioning valve where it is teed into two. One to the rear and one to the caliper. |
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| jherman93 | Oct 9 2012, 09:23 AM Post #7 |
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Ok thanks guys for clearing things up! I'll definitely check the rubber hose and wheel cylinder.
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| sphenicie | Oct 10 2012, 07:03 AM Post #8 |
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may i strongly suggest the wheel cylinder. but if it is the prop valve i have one that you can have, same for hose. but hurry, i am leaving fri, for 10 weeks.
Edited by sphenicie, Oct 10 2012, 07:05 AM.
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| jherman93 | Oct 10 2012, 02:07 PM Post #9 |
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I'll look into that. Thanks for the response! Check your PM.
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| jherman93 | Oct 13 2012, 10:31 AM Post #10 |
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For all that are interested, it was in fact a swollen rubber brake line. Thanks again to everyone that helped!
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Probably pretty muddy.
If that's the case, the entire system is muddy up too.
Much, much bleeding & flushing May cure the situation.


9:30 AM Jul 11