Senior Tech Team
Join Date: Feb 2004
Location: Fayetteville, AR
Question on 71 chevelle brakes: disc/disc valves
Note: this is not a recent or short term issue, but one that I've been living with for years, there should even be old threads similar to this on here
I am looking seriously at buying a brand new combo valve made for a disc/disc car. Past that I have exhausted every thing I know to get this car to stop better. Is there any hope that this valve could be the cure or am I just blowing another $60 plus fluid and likely some hardline splicing for nothing?
My 71 Chevelle has never really stopped worth a crap. It was originally a drum/drum car. I used a 70 model donor car and transplanted the disc setup including the fluid valves for the front line and the one above the rear axle. The front line valve was giving me issues with bleeding so I just removed it and braking showed no change but I was able to bleed the fronts better and get a better pedal feel.
I used a brand new disc booster, and have since replaced that one yet again due to a leak. I have a brand new master cylinder for a 1970 with disc brakes. I also put on the pedal limiter from the disc car. The master cylinder and booster pin is the correct length.
I recently switched the rear drums for LS1 fbody discs with stock type pads and rotors. Front calipers were replaced, rear calipers are new
Front pads are Hawks HPS but in the past I have used everything from cheap metallics to ceramics, the Hawks just don't fade when I'm driving the car harder for longer periods.
Fluid is fresh Super Blue ultra high temp DOT3, front lines are fresh rubber, rear lines are fresh rubber
Car weighs 3650lbs with me in it.
When applying the brakes they almost seem to "creep in" rather than applying force instantly. From a low speed roll you can hit the pedal hard and it will slow then finally once the car is almost still catch and stop. They get better and have more instant bite when the pads get some heat in them, but still never anything like even the old 79-80 Chevy trucks I've driven and certainly nothing like even a stock new car.
Unless you are going high speed or on poor pavement, even the most forceful brake application will not get so much as a squeak from the 235/60 up front or the 295/50 hard as a rock crap tires out back.
My dad's 69 Chevelle with stock brakes will damn near break your nose by the time you press the pedal an inch. Mine will travel about half the total pedal travel, it is firm but gets very stiff about half way.
Feel like I'm beating a dead horse here, but I really can't believe this car with every brake upgrade shy of huge rotors and dual piston calipers or stainless braided lines should be this hard to stop.
Pro Touring 1971 Chevelle SS clone
head/cam LS2, 4l60e, 3.42 12 bolt
1.61 60ft 7.17@95 1/8th 11.33@117 1/4