Ok I recently deleted the ABS system on my 95 LS shell following the guidelines and tips posted on other threads I found in HT. I figured this would be a great project to do before I drop in my motor.

I obtained a 40/40 prop valve from a DA, converted the prop valve bracket from an EG to fit my firewall, replaced the 2 front hard lines (the ones the run from the prop valve to the front calipers) also obtained from an EG, bent and flared the 2 hardlines that goes from the prop to the master cylinder. Note: I did not replace my brake booster or master cylinder.

All seems to go smoothly until I got to the brake bleeding process. Also following the proper sequence, I bled the brakes starting from the passenger rear, then front driver, then rear driver and then finally to front passenger. I had a friend pump 10x and hold the brake pedal while I release pressure from the valves. I repeated the process until pure fluid came out on all four calipers.

Here's the problem....

After putting the car back on the ground, I decide to test the brakes. Being that I was parked on an incline I decide to let the car roll back just to see how it will do. Upon the first few attempts the car stopped great. BUT, after holding the pedal down for a few seconds, I notice the pedal slowly sink to the floor and car started to slowly roll back.

Since then, I re-bled all 4 calipers 3 times using the "pump-hold-release" method, and twice with a brake bleeding kit I got from Harbor Freight. Im still having the same problem.

Can anyone tell me what Im doing wrong here? Do I need to replace the MC and BB to a non-abs one? Could my Prop-Valve be faulty?

I checked all the hardline connections on the prop-valve, mc, and all seems to be air-tight no apparent leakage.


PLEASSSSE HELP!!!!!!!!!!

 

I have not deleted my ABS, but I did have to work the air out of my calipers with a rubber mallet.

When I thought that all of the air was out...it wasn't.

I used a piece of plywood that was (about) the thickness of my rotors, as a substitute for the rotor.

I held the caliper in one hand and hit it a few times with the mallet. I turned the caliper upside down and hit it some more. Then I held it side ways and hit it some more.

Then I had someone pump the brake pedal a few times and I let out some more air.

I did this to all 4 calipers and got air out of 3 of them. No more spongy brakes.

 

sounds like you are bleeding the calipers in the wrong sequence.

98-01 is front left, front right, rear right and rear left.
94-97 is rear right, front left, rear left, front right.

 

Thanks for the tip! Im willing to try anything at this point.

 

since my car is a 95, the sequence I followed were the same as you listed for the 94-97:

pass rear, front driver, rear driver, front passenger = rear right, front left, rear left, front right

 

Sounds like a bad master cylinder... it leaks internally from the seals and lets off some pressure.

I also had this problem after a year... it ended up being the hardlines that ran to the back were rusted, one one had a hole it it, eventually letting al fluid out and resulting in me losing the brakes. The little shitty shield/plastic cover has a metal clip that clips to all the lines, it rusted inbetween. My car is a 1995 GSR.




You might not have the same problem, but it's worth a look.

 

hah! imagine that. sorry, bud.

 

the master cylinder may need to be replaced. the first time I bled my brakes completely and bled them the proper way, the seal went on my MC. over time the seal around the piston adapts to the fluid it is compressing, and when air is added to the MC (draining your brake fluid) the seal becomes ruptured, thus allowing air blow by, even though a steady stream of fluid may be coming out of the valve on your caliper.

 

Thanks for the info guys. I'll be sure to check my rear lines and look for any corrosion.

Rayza, Is there any visible indication of a MC seal going bad? I did a thorough check on the BB and MC area while my friend was pumping the pedal during the bleeding process and saw no leakage.

 

well let me apologize for going in reverse order lol, ... did you bench bleed the MC after hooking up the new lines to it?

 

Doh! I didn't think of bench bleeding my existing MC as I thought that was only required when replacing the MC with a newer or rebuilt one. Should I remove my existing MC and bench bleed it?

 

Mystery solved! It was the master cylinder. Replaced it and no more pedal sinking. Thanks for all help fellas!