Tinker Posted February 23, 2006 Share Posted February 23, 2006 Having some ongoing trouble with my 93 ABS equipped Pathy. Distinct lack of rear braking pressure despite replacing drums, wheel cylinders, master cylinder, calipers, pads, assorted brake hardware, etc. Full system bleed performed after each component replacment, of course. Problem is present regardless of whether ABS fuse is installed or not. Is it possible that the proportioning valve (mounted on the passenger side frame rail) is causing this? Its supposed to reduce braking pressure to the rear axle to prevent end-swapping under hard braking - could it be stuck? I still seem to get good fluid flow when bleeding, but the pressure could be substantially reduced without noticing it during bleed? Suggestions? Link to comment Share on other sites More sharing options...
87pathy Posted February 24, 2006 Share Posted February 24, 2006 Yes it is. those valves work more or less like any other hydraulic valve. Depending on how it works inside, the piston or ball wich could be froze up or the springs behind it could be broken or worn, there is alot of variables in how the insides of these can work, ALTHOUGH, i have never had one off of a nissan taken apart, but i work with that kind of stuff every day.. hydraulics of all kinds and makes.. Link to comment Share on other sites More sharing options...
88pathoffroad Posted February 24, 2006 Share Posted February 24, 2006 If you've replaced everything BUT the proportioning valve and it still has a problem, what does that tell you? Link to comment Share on other sites More sharing options...
RedPath88 Posted February 24, 2006 Share Posted February 24, 2006 (edited) Ok I am not entirely sure how the Pathy valve works.. soooo I am going to look at it like my Yota's (because I am to lazy to go out to the garage right now and look)... Does your truck have a suspension lift? *Will go out in a while and take a good look at the system Edited February 24, 2006 by RedPath88 Link to comment Share on other sites More sharing options...
Tinker Posted February 24, 2006 Author Share Posted February 24, 2006 No lift kit installed. While sourcing a replacement the folks I talked to (including the Nissan Dealer Service rep) stated that they had never heard of one of these failing, so I decided to throw the question out to the experts here. I haven't come across a lot of info on these, which would tend to support the dealers claim of near invincibility. Then again, he probably doesn't see too many 350000 km pathys. What I was hoping for was a quick, easy to perform, rock-solid, yes/no test, specific to this part and completely infallible! Link to comment Share on other sites More sharing options...
Tinker Posted February 27, 2006 Author Share Posted February 27, 2006 Replaced the valve with a $20 wrecker part - braking performance much improved but I still can't get the rear end to lock up - I'm hoping this'll improve once the adjusters have had a chance to dial in. Appears that problems with this item can cause the both the front and/or rear brakes to drag - I'm guessing it restricts fluid flow in both directions if its pooched. Anyone tried bypassing it? Link to comment Share on other sites More sharing options...
88pathoffroad Posted February 28, 2006 Share Posted February 28, 2006 Mine never had one and my rear brakes still suck. It's safe to toss it out if you can find a way to loop the lines together again afterwards. Link to comment Share on other sites More sharing options...
RedPath88 Posted February 28, 2006 Share Posted February 28, 2006 Mine never had one and my rear brakes still suck. It's safe to toss it out if you can find a way to loop the lines together again afterwards. See now that is what I was thinking... that there was not one. (thus my earlier statement about not knowing Nissans setup for them) I was just under there and I failed to look.. was messing with the coils. But I don't recall anything that resembled a proportioning valve or lever Link to comment Share on other sites More sharing options...
Tinker Posted February 28, 2006 Author Share Posted February 28, 2006 Thanks guys. Tying the lines together shouldn't be a problem - just need a double female flare fitting - I might try the bypass if it gives me any more grief. ABS was bypassed anyway after the sensor on the rear pinion failed. I'll leave it with the factory set up for now - I have a line on a rear end for rebuild from the wrecker - $150 if I pull it - if the ABS sensor is in good shape I may want to put it back into operation, although rear-only ABS sounds kinda jam-tart. Those shrieking rear tires are a nice indicator for threshold braking! Link to comment Share on other sites More sharing options...
jonathanjdfraser Posted March 4, 2006 Share Posted March 4, 2006 well, just to throw it out there, i have the exact opposite problem, lack of front brakes at all, and my abs works fine in the rear, if its slipery at all, my rear wheels will lock then abs will com on, it seems like my front brakes are barely there at all. its is very strange though, because if i put it in 4 wheel drive, i have twice as much braking power.. WHY?? lol, i think that its cause abs is removed from the braking system, but why do i have much more braking power. And ive guessed thats its the same valve, i believe its mounted under the right rocer panel between front and rear door.. Link to comment Share on other sites More sharing options...
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