Brake problems?

[Bob Mulry]

Hi Art,

Since you have committed to a new M/C, why don't you consider going to a smaller diameter M/C if one is available for your application?

A larger caliper or a smaller M/C = the same thing. It's just a ratio of the areas...

One thing to be careful about with increased pedal ratio and a smaller M/C or larger caliper is the total brake fluid displacement per stroke.

Go too wild and you would have to pump the pedal to get enough fluid to apply the pads.

Just my thoughts,
Bob

[A Closkey]

You didn't use Silicone fluid, did you? This stuff will produce a crappy pedal.

[art leong]

I'm using a 7/8 master cylinder now. I've talked to some of the brake manufacturers, and they don't have anything smaller. That is why I'm going to see if I can change to a larger piston caliper. I now run a 54mm (2 1/8") pston. I'm hoping to use a 60mm (2 3/8) With the 22mm (7/8) master cylinder. The master cylinder (power brakes) for that application is 24mm (15/16).
I'm hoping to get the car to hold at a higher rpm against the foot brake.

Regular brake fluid not #5

[chris ok]

any new news yet?
Are you using factory stuff. mopar has some real light aluminum calipers made by trw of mexico it is I believe.
have you driven car around at all. I say you can't just run it without driving it to settle all brake parts and get a real feel. Good luck Art. Chris.

[art leong]

Put a new mastercylinder. Still have the problem. Bench bled the new master. Bled the brakes over and over. Doesn't seem to make a difference. The pedal seems a bit spongy. Checked all the fittings there doesn't seem to be any leaks.
On the jack stands I can ony hold the brakes to 3000 then the wheels start to turn.
I think it would be a little bit more rpms with the wheels on the ground.
Going to try to bleed them one more time. Tomorrow. With someone that I know can pump and hold. If it doesn't get better I'm going to put it on the ground, and try it.
If not I'll just leave at 2500. I doubt there will be any trouble stopping at the finish line.

[art leong]

Put a pressure gauge on them today. With left foot only pedal I got 1100 psi on the front.
600 on the rear. Before I changed the ratio I needed 2 feet pressing as hard as I could to get to those numbers..
Does the difference from front to back seem correct? I have an adjustable proportioning valve.
Hoping that when I put it on the ground I will pick up a few hundred rpms in holding against the converter.

[Eddies66]

http://www.carcraft.com/techarticles...der/index.html

[art leong]

Originally Posted by Eddies66

http://www.carcraft.com/techarticles...der/index.html

Thanks for this I read it and it answers some of my questions.
But the Chrysler FWD cars. are biased brakes (?) the front part of the master supplies the right front and left rear wheels, the back chamber supplies the left front and right rear.
I have changed all that and and now my 2 front wheels are supplied by the rear part and my rear wheels are supplied by the front section.
One thing that the article brings to light is that my fronts have 54 mm pistons my backs have 34mm pistons. The stock setup would supply a 54mm and a 34mm piston. Now my fronts call for two 54mm pistons. I wonder if I have the volume to supply them? The master cylinder is 22mm. Not sure of the stroke though.

[Eddies66]

Originally Posted by art leong

Thanks for this I read it and it answers some of my questions.
But the Chrysler FWD cars. are biased brakes (?) the front part of the master supplies the right front and left rear wheels, the back chamber supplies the left front and right rear.
I have changed all that and and now my 2 front wheels are supplied by the rear part and my rear wheels are supplied by the front section.
One thing that the article brings to light is that my fronts have 54 mm pistons my backs have 34mm pistons. The stock setup would supply a 54mm and a 34mm piston. Now my fronts call for two 54mm pistons. I wonder if I have the volume to supply them? The master cylinder is 22mm. Not sure of the stroke though.

Art,

I found this blog that may give addition insight to your situation: http://forums.nasioc.com/forums/show....php?t=2076386

[art leong]

Originally Posted by Eddies66

Art,

I found this blog that may give addition insight to your situation: http://forums.nasioc.com/forums/show....php?t=2076386

Thanks. I'll look that over. Ironicly I was looking on that forum to see about hood Subaru hood scoops. To cover my four throttle bodies when I put them on.