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Discussion Starter #1
Long story short, I been buildin the ranger for about 2 years now. Had all the brake lines off so the master went dry I guess. Anyway I got all my new lines hooked up and filled the master and gravity bled the calipers last saturday. Did the usual pump and hold and after 15 min I had awesome brakes I mean they were perfect. Drove around slightly to test them and everything was fine. Pulled back in the garage to finish up some other things and after a few hours I went to park it and realized my brakes were no good. Pedal to the floor. They would stop me but they are barely there. Figure I blew the master cylinder. Replaced and bench bled it and did the normal pump and hold and I got a solid powerful stream out of each caliper but the pedal is still very soft. Half ton chevy calipers at each corner. I can craclk each bleeder and fluid flows and I have zero leaks. What the hell gives here? Booster gone bad? Everything is new except it and they were perfect at first I just don't get it.
 

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What are you using for a proportioning valve? Stock valves can be tricky for bleeding front. If you don't know how, you need to learn how to do submerged bleeding at each wheel starting at the farthest wheel from mc and working to closest. It sounds like air made it to prop valve and will hang out there indefinitely if you can't squeeze it out.
 

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Discussion Starter #3
So you're thinking its NOT the booster that is my problem? The prob valve is right on the frame under the master cylinder is it not? what is submerged bleeding, or should I just Google that for myself lol
 

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Discussion Starter #6
If flow wont be right, why was it that I had PERFECT braking when i first bled the system? something somewhere went wrong/failed and its beyond me what it is. If everything was right at first, and my brakes were great, how is it that after some time sitting in the garage, maybe 3 hours later, shit turns sour on me? I could see if I had problems right off the bat, then I'd be suspicious but that's not the case, i don't see that being the problem, incorrect flow that is, due to the proportioning valve, unless it has failed.

What gets me is that I have solid powerful streams of fluid out of every single caliper, the front driver being the most powerful and the back passenger being the least but it shoots out very well. Back to the old drawing board I guess, wish I didn't scrap my parts ranger, or a least kept more shit from it.
 

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Scrap the stock valve. Get an adjustable unit.
When I did my disc swap with hydroboost my rears would lock up. I took out the stock valve and it still did it. I then put in a willwood adjustable one and dialed it down on a couple runs until it was perfect with borderline lockup in the rear with 44's.
I've got Very strong brakes!
 

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First get the air out, then decide if you need to change the valve. If your rears are locking up first you should change to adjustable.

Start with the right rear. You'll probably need 2 qts. of clean brake fluid. Pour a half of quart into a nice tall container, or pour half of a quart into a clean container to use later and just use the brake fluid bottle. Loosen the bleeder and put a tight fitting hose over the bleeder that reaches well into the fluid in the bottle. Have someone slowly pump the brake pedal while you watch or listen to the fluid coming out. Once the air has stopped completely, then stroke it 3 more times to be sure. This gets all the old nasty fluid out too. Tighten the bleeder while the hose is still submerged and make sure the reservoir in the mc stays full. Do the left rear wheel the same way. The submerged hose prevents air from being sucked back in so you only have to open the bleeder once to start, and then close it once when you are done as long as the hose stays submerged. The old fluid doesn't get sucked all the way back into the system but it provides a seal so air can't either.

For the front I recommend taking the calipers off the rotor to start with. Start with the right wheel. Leave the other caliper on the other wheel until you are done with the first. Open the bleeder and pump the pedal till clean fluid comes out. Now close the bleeder and gently pump the pedal till the piston(s) are fully extended. Now open the bleeder and push the piston(s) all the way back in 100% of the way. Now close the bleeder and pump the piston(s) out again. Make sure the m/c reservoir is only about 1/2 full. Now with a clamp or clamps push the pistons all the way in again but with the bleeder closed. This will push the fluid back into the mc and hopefully scrub any air getting caught up in the prop valve on past it where it can make its way up to the mc.

Now put the caliper back on the rotor and do a submerged bleed like the rear. Even if there's no air, pump the pedal an additional 6 or 8 times anyway and keep the mc full. Repeat the whole front procedure for the last wheel and you should have nothing but a minute amount of air left in the entire system which will now be easily forced back to the mc via overwhelming hydraulic pressure and volume.

For anyone who has drum brakes, you must first make sure your shoe linings are adequate, the drum i.d. is not oversized, and that the shoes are installed properly and adjusted nice and snug against the drum so that you cannot turn the drum easily by hand but you can turn it by the wheel with little effort when it is back on.

My advice with calipers is never push the pistons back in with the bleeders open unless you are going to follow it with a full push back to the mc with the bleeder closed. It may be an expedient way to collapse the calipers, but you will almost certainly ingest air into the front lines, which due to sequencing nature of the prop valve, makes it nearly impossible to make its way past and on to the mc to exit the system.

Of course you could buy a pressure bleeder, and blow all of the snot out of all 4 lines at the same time and be done with it in a matter of minutes if you like. :smokin:
 

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Discussion Starter #9
I wish i knew someone who had one, they are too rich for my blood, I'll suffer the old fashioned way. Thanks buddy, I'll give this a try over the weekend.
 

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Discussion Starter #10 (Edited)
so,,,,
ended up changing out the booster because nothing above worked. I have front brakes now, still no rears, well I shouldn't say that. I have a soft, goes to the floor, pedal, However the rear calipers are moving, which looks to be typical throw, and when the brake is pressed I tried spinning the rotor with a pry bar and couldn't move it, but didn't try it with the tire on. Found out I do NOT have a proportioning valve, unless its built into the master cylinder. What I thought was the prop valve is the ABS module in which I removed and hard wired the connection with a union. Funny, 3/16" line with a 1/4" fitting, stupid. Anyways after eliminating it and still no brake I ended up putting it back on. Took the calipers on the rear off completely and held them so the bleeder was at 90 straight up and bled them like that, still no pedal. I stopped working on them for two weeks because I had to move to something else or I would have gone crazy working on something that i cannot fix. I just dont understand.

Fluid, check
No leaks, check
ALL fresh new lines except one, which was replaced about 4 months before I parked the truck two years ago
New calipers, pads, rotors, banjo bolts, copper washers, brake hoses, check.

The master cylinder I bought was said to be brand new from the parts counter, however, could it be a bad one? I would like to think that if it were bad, the fronts wouldn't work. I can lock the fronts up all day.

I've got a shakedown run coming up next weekend, actually its a little hog roast some ppl have each year first weekend in March and I've not attended for quite sometime and I was all pumped up about going but I refuse to wheel with only front brakes, that has bad news written all over it. I'm going to work on it tomorrow as long as I can stand too but really don't even know where to begin now.
 

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I would say go over everything again with a bright ass flash light. Check Every connection, starting at the rear, and work your way forward. Once you get up to the master cylinder, make sure it is good and full, and just start pumping your brakes with all the bleeders closed. I mean pump them even after the pedal is firm, for a couple minutes, and I'm talking with the engine off. After that, Once you've pumped for a few, and you've got a firm pedal, prop it down or have somebody hold it down while you check everything for leaks AGAIN with a flashlight. I don't care how bright it is outside or where ever you are working, get a flashlight. I'm talking check bleeders, fittings, banjo bolts, piston boots, EVERYTHING. The entire brake system.
If you don't see anything, and I mean no fluid on anything (because regardless of how new the calipers are they could be leaky too), THEN go ahead and exchange the master cylinder. If that doesn't fix it, then you may need a proportioning valve.

Is this a split system? How many lines coming off the master cylinder?
 

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Discussion Starter #12 (Edited)
There are two lines coming off the master and it's definitely a split system.
I did a little reading this morning and found out that the ABS module COULD be effecting this. I guess it acts, sort of, like a proportioning valve and it could end up stuck in one position trapping air. Seems to make a little sense and here's why. The front calipers are not associated with this module and they produce a stream of fluid so strong that I know for a fact the front system is fine. The backs, however, shoot out but no where near like the fronts do. I think I might remove that abs module and connect it again with a union, take my time and re-bleed everything, even might remove the master cylinder and bench bleed it again. I would rather cut the entire suspension out from under it again and re-install it rather than fawk with a brake system.
 

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First things first remove that POS RABS valve!!! They r junk and gum up and never work properly!!! Just bypass it, but i would leave it mounted and pluuged it or you are gonna get ur ABS light stuck on your dash(ask me how i know) If u have good front brakes and shitty rears i would venture 2 guess


1. U have a small pin hole leak thats allowing air to slowly seep in one of the rear lines.

2. that ur brake shoe adjusters are not set up right and need to be readjusted to grab sooner.

One thing that i like to do to check my system for leaks is get a spray bottle and getr it full of realy soapy water and then spray in on all the brakes lines and in theory when u have some press the pedal if there is a leak u should see bubbles coming from the whole.

I hope this helps ya i just went threw the same exact shit with my ranger.
 

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Discussion Starter #14 (Edited)
Well this is a buggy that I plan to drive on/off road which is why I built it the way I built it, however, if the lights are on, i'll just take the bulbs out because them being on don't tell me anything, now anyways. I had it off before BUT i didn't bleed the rear brakes with the calipers off with the bleeder pointed straight up like I did last night so I might get somewhere if I do it again with it out of the picture. Secondly, I dont have shoes or adjusters, I have 1/2 ton chevy calipers, and 3/4 ton rotors at each corner. But now I'm thinking it could be that valve. In theory, If you have hard line with no valves or junk in route to the back two calipers, hard line to the front two calipers and the fronts work and the rears dont and absolutely have no leaks anywhere, the only thing i could think it would be is air is in the system SOMEWHERE, the master is no good or a caliper is bad. Would any of the above fail and still produce a little bit of pressure or when they fail they fail play no games?
 

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So let me ask you this, on the rear calipers, is the bleeder valve above or below the lines coming into it??

And no way ur master is bad if ur getting solid pressure and brakes up front. like u said sounds like air in the lines.

they other u can check to see if one of your flex lines isnt bulging when u hit the brakes. I absolutly hate brake systems but they are kinda neccesity to drive a vehicle:homer:

Goodluck
 

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Discussion Starter #16 (Edited)
above them, slightly. My calipers are mounted like this: http://pirate4x4.com/tech/billavista/Brakes/images/mounting.JPG and if you read billavistas brake bible you can see that they can be mounted anywhere IF they are bled properly how he describes, which is exactly what I did last night. The hoses going into the calipers are brand new so I doubt they are swelling or flexing and the line coming down to the splitter on the rear end is stainless steel braided so its not flexing/swelling. I had the same problem with my clutch and it turned out to be the master cylinder was full of air, after I removed it and bench bled the prick my problems were solved but I dont think that's my problem, or could it be????
 

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Discussion Starter #17
so,
looks like my next move is to upgrade my master cylinder. I've bled and bled and bled each and every different way possible and still have no back brakes, well I cant say I have none, the rear calipers are moving but no where near enough to lock them up. I've removed the abs module, replaced the only other line that I didn't replace when I installed all these new ones and checked EVERYWHERE for leaks to find nothing. The master cylinder is stock and from what a few ppl have been telling me, if there is no air and the calipers are working but not pushing out far enough for lockup, that means the master cylinder is not big enough. Thought I maybe would have been able to get by with the stock one but turns out that's probably not going to happen. I heard the use of an f350 master cylinder bolting right on, any truth to this? If not, which one could I use that would suffice?
Thanks for all the previous help guys.
 
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