well people i'm just about to set fire to my 2 of my irocs (88' and 89'). the problem both of them have is that the brakes just suck and the front wheels lock up when more than moderate pressure is applied. when i jack up the rear on both cars, and apply the brakes as hard as humanly possible the ****1ng rear wheels keep spinning. they both have the aluminum PBR setup. is this normal? do all f-bodies have this problem? or not? i have bled the living crap out of the both of them and have used a couple gallons of brake fluid by now. i have replaced rear and front rotors, pads, brake lines, and front calipers on both vehicles. does anyone have any idea on what could be wrong? could it be the proportioning valve? and if so how can it be tested. could it be the master cylinder? how can a master cylinder be tested? bad calipers? well that's all for now. if i can fix this problem i am going to set fire to my beautiful yet a pain in the *** cars. well thanks for any help or suggestions.

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86',88',89' IROC-Z, 350 TPI, 700-R4

94' Formula, LT1, 6spd

 

Sounds like the proportioning valve. Was this originally a "rear drum" setup that was converted to 4 wheel disc?

With 4 wheel disc, they tend to have less pressure on the fronts and more on the rears than a rear drum setup. When people convert a rear drum to 4 wheel disc, they are suppose to change the proportioning valve.

 

well they were both 4 wheel disc. the 89' brake system came with the PBR setup. on my 88' i changed it to the pbr setup from the screw in type caliper setup. if this has any relevance to my problem..... i have checked both brake systems and they both have the A50 master cylinders and have the same prop valve----> First Design With 4-WHL DISC BRK(J65) Without (1LE) USED W/M1.0 TUBE NUT THREADS BROADCAST CODE NB . thanks for the reply.

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86',88',89' IROC-Z, 350 TPI, 700-R4

94' Formula, LT1, 6spd

[This message has been edited by mystikkal_69 (edited September 27, 2001).]