Well i have done a ton of searching and i have a lot of ideas but i am not sure the direction to go yet. Here lies the problem.... i have almost no brakes at all. Pump them up with the truck off they seem fine, start it and the pedal goes to the floor. I have used a Vac to bleed them and the traditional "girlfriend method". Nothing but fluid coming out. It has me seriouesly reconsidering all of the brake work i have already done. I attached some pics for reference and some dumb ass newbie questions listed below. Here is what i do know. Master Cylinder- 1 1/8 Speedway PN 910-31440 BOOSTER- 8 DUAL DIAPHRAM BOOSTER Speedway PN 910-31435 PEDAL ASSEMBLY- 47-54 CHEVY PU Speedway PN 910-31977 Modified the pedal a bit to work in the IHC. Ratio is 5.5/1, 1 1/4" travel for the push rod. 1. Is my e-brake properly adjusted? I hear this can be an issue. 2. 2lb residual pressure valves i know are leaking and but do they need to be closer to the MC? Right now the front is about 12" the rear is about 24" from the MC. going to get some from ECI i think. 3. Do i need a combination valve? Right now i just have a wilwood proportioning valve going to the rear brakes. 4. Maybe my calipers are holding air? I am about at wits end with these brakes right now. Hope the experts can shed some light on the subject. Thanks in advance.
Looks like rear bleeders are down(reverse calipers side to side- will also put the E-brake cable in a better orientation) . If RPV are leaking fluid then they'll suck in air. Don't believe location of RPV makes much difference. Clean everything off, bleed and put constant pressure on the system to find any leaks. May have a bad M/C/
Take the calipers aloose and rotate the bleader to the top and see if there is air in the cylinder. If this is an complete aftermarket setup, you should call tech.
as said unbolt calipers and bleed them with the bleeder at the highest point. just put something between the pads when you bleed them off the rotor.
Residual check valves need to be as close to the m/cyl as possible; The pics don't show exactly where they are. 2 psi, for disc. Ditto, the bleeders on TOP. 4TTRUK
Thanks for all of the help guys. I spoke to a brake tech at MBM today he suggested a Combination valve (on order), and moving the 2lb valves closer just as you suggested. Once i get the parts i will bleed them with the rear calipers off and see if maybe i have them reversed. Thanks again, i will let you know how it turns out. Nothing worse than finally getting the truck running and driving, then realizing you can't stop!
Hi: Had a similar problem. Installed a 12 volt vaccum pump to maintain the correct vaccum level and problem went away.
I will test my vacuum tonight and see what i have at idle. What set up did you go with for your pump?
I have seen one post (I don't remember where) that said when using the camaro style rear parking brake calipers with the external springs, a 10PSI residual valve works better because of the large return spring.
I replaced calipers on an OT car once and couldn't get it to bleed and finally called a buddy of mine to double check me. He came over and took one look and started laughing. He said "If you fart in the bath tub, which way does the bubble go". I immediately saw it - I had put the calipers on the wrong sides and the bleeders were on the bottom! I must have looked at that 20 times and never caught it! I guess it can happen to anybody, right? Uh...errr.......right???
I have just about the same set up on mine and my brakes suck also. I am going to reverse bleed them and try and blow any air bubbles up to the MC. I will keep an eye on your post to see what happens to your and If I get mine fixed I will post how I did it.
Sounds like a plan! I'm going to dig into them thursday when i get my new 2lb residual valves in (moving them closer and shit caning the speedway ones). The mean time its bodywork galore.
I have 4 wheel discs on my roadster. 4 piston Kelsey Hays. Corvette M/C. I bleed them this way. I take 1 Caliper and pull the mounting bolts out and have thedarling wife pump up the pedal while I hold the caliper so the bleeder is up then bleed it. I do the farthest one from the M/C first. This has worked for me. Also Disconnect the booster and see if your pedal still goes to the floor after you have gotten a good pedal. It might be that the booster is bad
Today i plugged the ole' mighty-vac into the booster and pulled 10" let it sit for about a minute or two and it held fine. I'm assuming this means the booster is good to go?
Just an update.... Got a new M/C (1 1/8", Corvette Style 9/16" 1/2" ports), and a combination valve from MBM brakes. Started to bench bleed the M/C and it is shot right out of the box. Leaking like a sieve from the back around the push rod. I will be calling MBM on monday to see if they are going to do anything. Picking up another one from a local parts store on Monday, let's see how this one works.
Both the front and rear calipers in this case are going to have to be bled "off-mount". Since, in both cases, the bleed screws are not at the top of the piston bore, they will have to be forced to be to bleed them. Pull each caliper, one-at-a-time, and place a nice solid block of metal where the rotor would be. You can pull the rotor too, and use that, if you don't have a block handy. Rotate the caliper until the bleed screw is at the top, bleed, and then re-mount. Repeat for all four, and you should be in the game.
I think if you can swap sides with the calipers to get the bleeders to the top you'll be better off in the long run. I'm also a huge fan of regular (non-power) brakes. One less thing to worry about.
Yeah, what Zman said. In the first picture, there is a L on the caliper. Is that one on the left side?
OK. New M/C, new 2lbs. residual pressure, new lines. Got all of the leaks taken care of (those pressure valves are a PITA!). Start the truck, pedal goes to the floor and doesn't come back up. At this point it has to be air in the lines. All of the calipers are oriented with the correct wheel, the bleeders are just not on top. I'm going to take the calipers off and twist them to bleed them tomorrow. Oh and i tested the vacuum, pulls a steady 20". Brakes= Next time it's manual brakes on the firewall.
FWIW I have 4wpdb on my ford. I used a universal read chicom 8" dual booster/mc assembly and promptly broke the POS MC rod, total powdered metal? junk. I read about them online, unsurprisingly they're not as good as the merican made ones. I got a big dual booster like 11" I think off a truck of some type, I found it through the autozone website and got a lifetime warranty (hah!) . I'm running it off the firewall with a chevy 2 pedal. I put in a adjustable prop valve I've never used. Anyway I couldn't get the hoses in front to seal, bought some braided and they work fine. I might have bought a new caliper too, can't remember. I also used speed bleeders at all corners. Those things I consider a must! for any brakes I work on. Total life savers. I don't have seatbelts so I can't press the pedal hard enough to lock up the brakes without killing myself. Honestly it was a helluva lot of work and probably would havee been worth it to just keep the rear drums, but I can't resist a challenge, evidentally. My ambition is much greater than my abilities, but even I got it fixed. I think I have 1 1/8" MC too, or maybe 1 1/4", it's massive. Oh also I read to tap the caliper with a hammer or something to shake loose any air bubbles in the fluid. I think god just smiled on me one day and finally they worked. It took forever and a day.
I have had 4 wheel discs on my 1940 Dodge since 1975, o/k so they are Oz PBR brand BUT YOU MUST HAVE THE BLEEDERS ON THE TOP TO START WITH............sorry, don't care what others say.........why would every manufacturer have the bleed screws on the top?..............for appearance sake?.........lol............good luck, andyd
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