Low spongy pedal

[flattype]

I have an 86 t-type with a vaccum brake conversion. These brakes are horrible I have bled out the brakes adjusted the rear shoes up no leaks wheel cylinders are dry under the boots. You get a nice high hard pedal when bleeding but as soon as you start the engine the pedal sinks down and the car doesnt stop very well. Am I missing something or does the car just have lousy brake performance after the swap? Any help is welcome as this car is way too fast to have weak brakes. Thanks Eric

 

[blackstallion]

Make sure the bleed the brakes good sometimes they feel hard when bleeding then there soft as hell when fire the car up,other than that I would look at the master cylinder if new when you installed it did you bench bleed the master cylinder?as well.

 

[flattype]

Yes we bled the brakes well. It looks like someone put an el cheapo rebuilt master on it recently I guess a bad master cylinder could cause this problem? Its not leaking. Maybe I should just try a good quality brand new master. Correct me if Im wrong but the booster either works or it doesnt right? Thanks

 

[John Larkin]

http://www.babcox.com/editorial/bf/bf60133.htm

This article will explain it all. New Napa master cylinder for a 86 Regal 307 V8, $85 bucks. Problem solved. Do read the article though.

 

[flattype]

Thank you John. I have made the brakes safe with the installation of a new master cylinder (for a vacuum brake car) and replacing the front pads. Very good article. The pedal is still a little low but it stops well and a panic stop is safe and predictable. Part of the problem is Im trying to compare this car to my last hot rod (03 mustang cobra) and face it that car just has much better brakes than a 86 Regal. Thanks again Eric

 

[John Larkin]

I feel your pain. Driving a new car daily clouds our memory of how non-ABS, lower-tech brake systems used to work and feel. I will tell you that a good crisp adjustment of the e-brake ( http://www.turbobuick.com/forums/showthread.php?t=122976 ) will help pedal feel also. I was given this advice years ago and it is valid. My GN now has a very firm pedal. I also have S-10 wheel cylinders and long shoes in rear so that may help some but not 100% confident it contributes.