HELP NO BRAKES ! ! !

[evildky]

ok I have been fighting this thing for a week, I have a 71 early model with all the wierd stuff, when I got it it had no fluid at all, I topped fluid tried bleeding system and got basically nothing from the front, I did not try the rear as I was planning a rear end swap, I got a rebuilt master from napa ($45) installed it, the front would bleed but without much pressure behind it when I open valve ( helper pressing pedal) I moved to the rear and basically same thing, will bleed minute amounts of air and fluid out and thats about it, I pulled the lined coming out of the proportioning valve or whatever it is on the fender and the fluid runs freely out, I put lines back on open rear bleeder and fluid oozes out but at a real snails pace, peddle seems to get pressure and looses it when you get almost completely depressed, what am I missing ? bad master ? some other boneheaded thing that I have not checked ? help please ! and do not suggest elaborate swaps I just want to get some brakes working and soon, worry about upgrades much later

[Guest ZmeFly]

first off yoru bleeding your brakes wrong i can tell you that. the correct order is right rear, left rear, right front then left front, in other words start furthest from the mc and work your way closer. second you should verify first, check all your metal lines and also your soft lines to make sure that they are all in good condition, also check that your master vac is working, also your wheel cylinders for the rear shoes, while there make sure they are adjusted.

 

with your friend in the car pump the pedal five times and hold pressure on the pedal, break the bleeder screw and see what happens. it wouldnt be a bad idea to replace your brake hoses anyway since they are not the expensive and usually need replaced anyway.

 

good luck and tell us what happens

[evildky]

I understand the furthest to closest thing, although I have heard good arguement for the other way as well, and yes with the helper pumping repetedly I only get small amounts of fluid with very little pressure, the lines are clear as far as I can tell, I disconnected line at rear, the little junction thing before it hits the splitter, and blew air through lines and nothing suggested a clog of any sort, I have already pulled and checked the wheel cylinders, checked the bleeders for obstruction and with the car off the booster does nothing anyhow, the booster only helps to reduce pedal effort so wether it works or not is a mute point for the moment, the problem is that there is very little pressure at any given corner of the car, of all the cars I have owned and worked on I have never had this problem with brakes

[Guest ZmeFly]

broken rubber brake hoses can also cause this problem. a quick way to check is when trying to bleed them just wiggle and move the line around a bit.. at a position where your removing the break or crimp in the worn line it it is worn it will work as it should

 

the only other thing i could think of would be the mc but you said you had replaced it. not trying to make you sound stupid but you did bench bleed it first right.

 

not saying that is the problem too but it could be bad also. if you checked all the metal lines and they are good and not clogged or rusted i would check the rubber hoses then the mc again just to be sure.

 

its all i can think of that would be causing your problem

[Pop N Wood]

If there was no brake fluid when you got the car, then my guess is the brake system is in pretty bad shape. The rubber can actually break down with time, turning into a sludge. The worst place for this is the MC, but you have already taken care of that. From there you turn to the calipers and wheel cylinders. I would most certainly replace the brake lines at all 4 corners.

 

Sounds like you still have air in the MC. If you have an air leak anywhere in the system, you will just keep pumping air through the MC. You are never really priming the pump, so to speak.

 

Try this. Clamp off 3 of the 4 corners by clamping a vise grips on the brake line. Don't crush the lines, just enough pressure to clamp them off. Then connect a piece of clear tubing to the bleeder valve on the remaining brake. Place the other end of the tubing into a jar with an inch or two of brake fluid. With the bleeder valve open about a 1/4 turn, get in and pump the brake pedal repeatedly until fluid starts to flow. Keep the MC resevour full. Pump a couple more inches of fluid into the jar. Having the end of the tubing in the fluid keeps you from sucking air back into the line and lets you pump the pedal quickly without shutting the bleeder valve each time. Make sure you close the bleeder valve before pulling off the tube.

 

Once you finish this, I would pump a full can or two of brake fluid though the brakes. This should flush out any crap that has accumulated with the dry lines. Then replace your brake lines, still using the tubing and jars to bleed.

[evildky]

well I tracked down the proble, thanks for the imput I guess it's hard to understnad the whole problem without being there, the early master has a tiny piston that is spring loaded and pushes against the inlet hole in the end, I disassembled the master and fount the ruber piece that seals against the hole was missing, swapped front piston assembly and had front brakes but no rear, took the thing back out assuming that the check valve of the rear piston was not sealing, it is sealing but the rubber sleave that actually plunges through the cylinder was not the right size and fit loosely on the piston, I replaced the rear assembly with my old one and now have all 4 brakes working, as for why not use my old master since I was using it's internals, the hole for the screw that holds the rear piston in had stripped out, thanks for the help, and if anyone gets a napa master take it apart and inspect it carefully before installing