Help me PLEASE!!!!!!!

[88convert]

I need some help here guys! I had a problem last fall, I had a chunck of steel on the road hit my RR brake line. I replaced the line and decided to go from SVO calipers to GT ones. When I took it for a ride the brake pedal was hard as a rock and required high pedal effort. I was told that I needed to change the SVO M/C to a 95 GT, I did and no change. I replaced the one year old rear calipers, had all the rotors turned, all new pads and no change. There is no prop valve, just an adjustable one on the rear.
I then went to an original M/C.....no change. The only thing left was the booster, and yes, you got it...no change. I hooked up a refrigeration vacuum pump and pulled a 23" vacuum and it still no change.
Yesterday I pulled the M/C, made a gauge and checked the push rod and it is a little too short. From what I have read, if that's the case you should have too much free play. If I'm pulling a vac on it and depress the pedal the vac level drops to zero and will not recover until I let off the pedal. With the M/C on, pedal travel is minimal, with the the M/C off the booster it goes right to the floor.

I am at a loss and need some help! I've got to get it ready for Carlisle. HELP!

By the way, it's an 88LX, 5 lug, 4wheel disc.

Thanks! Ralph

 

[rd]

The car was originally a drum rear brake car. Changing the master cylinder should have gotten you one for a rear disc brake setup. However, some odd things to check, make sure there is not a drum brake residual valve in there somewhere. These sometimes are in the m/c rear brake outlet fitting. Most likely that function was done by the original proportioning valve.

You say theres no proportioning valve, but say you have an adjustable one on the rear brakes. NOt sure what you mean. The original setup had a combination valve in there, with the brake failure warning light valve/ switch, and a proportioning valve for the rear, in the "combination valve" that is under the master cylinder. If you added another, you now have two.

Had a Scout with this problem, and locked up brakes once, and the m/c pushrod turned out to be too long. It would not let the m/c piston come back far enough to open the return passage, and the brakes stuck on, with the pedal feeling hard.

I can't easily suggest a fix, other than to get a set of parts that's proven. It could be that the m/c diameter is too big, losing advantage to the larger rear disc calipers.

The booster is supposed to give a harder pedal feel when theres no vacuum. Its a sign of failure when it has high pedal effort when the engine is running. Also make sure the vacuum check valve in the booster is ok. Its the plastic thing the vacuum hose goes onto.

I'm (obviously) not a brake expert, but some of the above should help.

 

[88convert]

The thing is, that they worked fine until the rear brake line was pierced. I wish I would have taken it for a ride before I changed the front calipers. The rears are 95 Cobra. I have had a stock, 95 Cobra and SVO M/C on it. There is no prop valve, only an adjustable one on the rear which is wide open.