I had a disc/drum setup in my 89 RS. I converted it to a disc/disc setup (Single piston) rear-end. I also installed Earl's Brake Lines. Well, they took some cutting to get in, and they were mislabeled, but oh well, thats not why I am here.

Anyway, I installed everything, bled the brakes, no air, all is good. I took it for a drive, I have a firm pedal, but very little brakes. Went back, bled some more, messed with the lines a little. (One was loose.) It was a little better, but same basic crap. Hard pedal, no brakes. It seems that all four brakes are lazy, but very noticeable in the rears. At 10 mph on a hydro lift, it took the rears about 3-4 seconds to stop with 0 resistance. I am kinda thinking the rear calipers are frozen. So, tommorow, I am going to test them.

The lines are putting out no air, the vacumn booster is working, I have good vacumn, the brakes worked good before the rear went in, I changed to the disc prop valve from the dealer.

My dad (30 year ASE master) things that my car might not be disengageing because of the stall converter. So, I will put the car in N and try it again.

Any ideas?

 

Is the rear disc aluminum pbrs or the pre 89 cast iron ones that could be your problem. Also i would upgrade you fronts to 1le if you have the money that is. I have the rear cast iron ones i need to get the pbr to get the full 1le setup its a paint in the ***.

 

I have the Cast Iron ones.

Will the 1LE brakes fit on 15" wheels? Or do I have to goto 16"?

 

Well i i had a flat on the left front 16" so i put a 15" on for the mean time fit fine.I think its the larger 13" baer brakes that need the 16" wheels.

 

See the rear cast iron calipers where used with a totally different master cylinder than u have yours in fine for the 1le setup tho or just the 89 and up z setup.The rear pbr's dont just bolt up to the pre 89 rear end either you have to pull the axels and put a different mounting bracket on.

 

Hmmm......

The 1LE's are 16" only IIRC. Thats why I had to send back one rear-end.

Does the Older MS put out more pressure? Would a performance MS work?

 

Just remembered something, I pulled the Master Cylinder from the same car that had the rear-end. It is the older style.

 

hmm well my front 1le's fit under my 15's. I dunno about the master cylinder i just know they r different and the rear brakes u have used a different 1.it might put out more pressure to the rear i dunno the pbr's might take less pressure. An adjustable proportioning valve might fix ur prob. Then you have to cutt all your lines and reflare them tho i think cause the threads r different.

 

Ohh u changed ur master cylinder??I would think u would be fine then cause the front brakes u have should be the same as the pre 89 irocs.

 

I just thought of somethin tho if u have a 89 i dont think you could of got the right yr proportioning vlave cause they switched the threads. You prob got like a 89 4 wheels disc valve and u need a pre 89 one but the threads r different.

 

Nope, everything fit fine. I changed all the lines on the rear-end. (Even the hard steel ones.)

 

No i mean the lines goin to the proportioning valve the threads on them r different between the yrs so if u tried to get a pre 89 valve the thread would be different.

 

I tried installing the one from that car, the difference was the big line on the bottom (14mm) was in the front and not the bottom.

Threads and all looked to be the same from a glance.

 

I tried installin the valve that came with my pre 89 9 bolt and the threads were different but everything else seemed the same.