Soft Brakes - Why?

[Zarati]

Car is a 94' D1. Brakes have alwasy been awesome. I am running a spacer kit on the front calipers that allows usign the RRC Vented Rotors.

Lately the Brakes have sucked. I thought it was the Master Cyl so I replaced it. They got slightly better but not much. No matter how much I bleed the system they alwasy feel like I have air in the lines. If I go ON BRAKES hard they are soft. IF I then release and go ON AGAIN then they firm up for a second.

Is there a Rear Proportioning Valve on this car? I dont see one. What about the ABS unit. Its non functional and I have no interest in fixing it. It used to brake great without it and had enought stopping force to easily lock up the fronts at any speed even with the bigger tires. 245/75-16. Now it can barely lock them up on Hardpack Dirt.

Has anyone seen seals go bad in the ABS unit that could cause this.
A Caliper thats not working right? No fluid leaking out but maybe air is getting in from somewhere?

Thanks

 

[Porter]

what brake fluid did you use?

 

[garrett]

DOT 3 may corrode lines, but it could be a booster failing. use DOT 4 (mineral base) of course. when you replaced the master did it come with a new O ring where it mates to the booster? might want to double check as it only takes 5 minutes.
as Chris always reminds us.......look in the booster to see if there is ANY fluid. if so it's been contaminated.
i went round and round with similar issues and forgot to install a new O ring. made a world of difference.
then again i could hear it leaking between the master and booster.

 

[Zarati]

I use Castrol GT-LMA. I understand thats the Recomended Fluid. At one point in the past I couldnt find any and filled with Dot-4 ATE SuperBlue. I've never had any problems with that fluid in the other 20-some odd vehicles my friends and I run it in but I have heard Rovers are Finicky.
The New Master has never had anything but the Castrol GT-LMA and I bled the entire system through until all the ATE -Blue was out of there.

If the Booster is bad, why would that make the brakes spongy? Wouldnt that must make the pedal really stiff with less assist? Is there a test I can do to test the Vaccum Booster? On Audis, they have a High Pressure Vaccuum canister and can count the number of Pumps until the pedal gets firm when the Vehicle is parked. IT should be like 20-pumps. But on Vacuum Boosters I think its normal to only get a couople pumps with the engine not running.