I have been trying to get my e-brake working properly. I put new seals in both the rear calipers but I obviously done know how to adjust the e-brake piston. On one side the cable only moves a little bit before the brake grabs. On the other side the cable almost moves all the way to work the e-brake piston. I have gotten it to where it will hold the car when the e-brake is applied. I went ahead and replaced the master cylinder because the car has sat a lot without being driven and the pedal was a bit spongy. Pedal is better now but when I tried to bleed the front brakes I get no fluid to either front caliper. I also noticed that when I was replacing the master cylinder the electrical connector to the proportioning valve is unplugged. I didn`t try plugging it back in but since there seems to be no pressure to the front calipers is it possible that the proportioning valve is frozen.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
I replaced the master cylinder with a rebuilt one. I took the proportioning valve apart and there`s not much to it. All of the o-rings look good and the valve is fairly clean. I think what is happening is the proportioning valve is "tripping" as it`s called. Which, is shutting off the fluid flow to the front brakes. I`m going to try a cheap insert which screws into the valve switch port and holds the slider inside from moving back and forth until you get all of the air out of the system. Then, just reinstall the switch.
The Balance Spool In The Combi valve that trips brake light on Maybe a problem. The Prop valve part in the combi valve isn't. The Spool does Not shut off fluid Flow even when does turn on the brake light. But crap in it might kill flow. Tube fittings are very small holes there.
Is possible you crimped the tube fitting in the MC, Combi or both. Many people way over tighten the nut and smash the aluminum at the "flare." Same in my Cave, Combination Valve pictures but worse.
Just a heads up, I attempted to bleed my brakes a few weeks back and was only able to get fluid to flow through the right rear. The solution was to replace the brake hoses, which have a tendency to clog up internally. Was a pain in the ass, but solved the problem.
The rear brakes have fluid flowing out fine. It`s just the front brakes. If I push on the pedal a few times I get a small amount of fluid but not enough to get the air out. The spool may not shut off the fluid flow but it seems to slow it substantially. I pulled the switch out and looked down into the comb valve and the groove is definately to one end more. I`m going to try to use the tool that I have ordered and if that doesn`t work the guts may be coming out of the comb valve and it will just be a distribution block. I know braking will be changed but with a mid-engine car I don`t see that front inertia would be as great as a front engine car in a sudden stop. I will probably catch flak from this thinking but so be it.
Balance spool moves and turn on the brake light by uneven pressure between front and back hydro lines. Often won't move by "pedal bleeding" because not enough pressure doing that. Moves easy when bleeding then switch is likely bad. Balance spool will reset itself when sees good pressure on both sides.
"I replaced the master cylinder with a rebuilt one." Rebuild MC can be bad right out of the box. If you pump the pedal and still no fluid flows w/o light pedal pressure then likely didn't bench bleed the MC or is bad. Block spool, lines or fittings as said above can require full pedal pressure just to pass even a little flow.
Take off front line to MC and look at the flare hole where actual line hits to seal. Do same w/ combi valve if you pull the line(s) there.
"I know braking will be changed but with a mid-engine car I don`t see that front inertia would be as great as a front engine car in a sudden stop. I will probably catch flak from this thinking but so be it." Front brakes do most of stopping the car no matter where engine is And that's w/ normal everyday driving. Panic Stopping, the fronts can reach 80 to 90+ % of stopping and lighten the rear axle even on a full rear engine vehicles.
Car static weight, IE curb weight, is not really relevant to stopping, turning, or acceleration loads to the wheels or axles because of "Weight shifting." Examples: At a drag race... FWD cars w/ FW slicks to very little vs Front Engine RWD using slicks on rear for same reason because Most of car's weight moves to the rear axle when you launch. This also is why you'll see Cement Trucks w/ Rear Engines dumping their loads on the road at traffic lights etc. Many don't see the actual truck dumping but often see wet or dry concrete on the road for no apparent reason.
I`m not sure what`s going on. I had an 86 and I had the same speed bleeders that I have in my 88 My 86 had an upgraded booster and a stock master cylinder and comb valve just as my 88 does. The 86 though, when you would mash the brake pedal with one of the bleeders open the pedal would drop pretty good and a pretty good amount of fluid would come out.
This is not the exact tool I got but the similar tool I got helped the problem I had trying to bleed the front brakes. Now, I get good pressure out of the front brakes in order to bleed them. https://www.youtube.com/watch?v=cxUjYp_MY0g
