[Vnova]

After going from front drum to front disc, I have alot of travel in the brake pedal before it reacts. I have bled the brakes numerous times with the pedal pusher method. When the car is off I can press the brake pedal 2-3 times and it gets real stiff and wont move anymore but when I start it the pedal goes down about 3-4 inches from the floor.

I thought there was air still in the system but I don't see any air bubbles in the clear tube when bleeding.

 

[RichP]

The pedal getting stiff when the engine is off is normal when you have engine running will it pump up and have a higher pedal if so then you still have air if not then try adjusting the rear shoes a little tighter. just my 2 cents worth.

 

[69AKDN]

After going from front drum to front disc, I have alot of travel in the brake pedal before it reacts. I have bled the brakes numerous times with the pedal pusher method. When the car is off I can press the brake pedal 2-3 times and it gets real stiff and wont move anymore but when I start it the pedal goes down about 3-4 inches from the floor.

I thought there was air still in the system but I don't see any air bubbles in the clear tube when bleeding.

How much free play is there in your pedal/pushrod to booster? The booster retains vacumn for several brake applications ( or one panic stop ) in case of engine failure...your system is reacting as it should. Have you adjusted your rear brakes?

 

[TizzDizz]

There could be some adjustment needed to the rod length that connects your pedal to the booster/master. I haven't gotten that far yet in my project, but I would double check that you don't need to lengthen the rod a little bit.

 

[Vnova]

Im using a disc/drum mc and the same power booster that was with the drum brakes.

Haven't touched the rear brakes, how is the brake pedal to rod adjusted?

 

[TizzDizz]

Oh, my mistake. I was thinking you had changed the booster, or gone from a non-powerbrake setup to power like I am. If you didn't have to disconnect the rod for your project, then disregard what I said earlier.

 

[64Chevy2]

Hey VNova,
not sure if this is what your doing, but when you bleed it, do it with the engine running, make sure your rear brake adjustment is good. Does the pedal feel spongy?

 

[Vnova]

I've always bled the brake with the car off.

Would my prop valve be causing this low pedal?

I'll have to check the rear drums.

Does the rod stay the same on the booster?

 

[Vnova]

I found this so I might check some things out.

http://www.mpbrakes.com/technical-support/troubleshooting-disc-drum-01.cfm

The only thing that it mentions about long pedal travel the master cylinder piston diameter.

 

[74 hatchback]

I did a brake convertion on a 73 before and i had to pump the pedal for hours, i finally got the fluid to bleed out on the second day.

 

[NOGO]

How is your brake performance?

When you upgrade to front disc brakes the caliper piston diameter is larger in diameter than the old wheel cylinders, so you displace more fluid and increase your pedal travel.

 

[Vnova]

I had my combo valve mounted like this

so i tried to mount it on its side and routed the left front brake line so its not looping up. I have the left wheel for the top and the right wheel for the bottom.

I moved the rear drum brake shoes out a bit. Pedal almost seems the same. Its like when you press the brake pedal you dont get a reaction soon enough. I have bled all wheels again, I get plenty of fluid through all wheels. Is there a way to tell if the rear brakes are adjusted properly? Right now they fit almost snug on the shoes.

Hmm if I put enough pressure on the pedal it will go to the floor. Im just about to take it to a shop and have them fix what ever is wrong cause I don't know.

 

[jeff66]

Vnova,
Are your calipers (brackets) square with your roters? if they are not the pistons can be pushed back when pedal is released. using more stroke to square up.

 

[John65ss]

There are 2 different length pushrods for the booster. Are you sure you have the right one for your master cylinder?

 

[Vnova]

There are 2 different length pushrods for the booster. Are you sure you have the right one for your master cylinder?

Im using the same one that I used with drums. Is that okay?

 

[Vnova]

I've noticed when I bleed the front calipers that I get some fluid leaking out of bleeder screw threads. Was thinking of get a pair of speed bleeders for the calipers maybe they would be better than bleeder screws? I will have to double check the flex hose and make sure its not leaking at the banjo bolt again.

 

[John65ss]

Im using the same one that I used with drums. Is that okay?

That depends. See the info at the middle of this page:

http://www.pozziracing.com/brakes.htm

 

[scott costa]

I'm with Jeff66. I've fought this issue on a couple cars. My caliper brackets weren't square with the rotors and my brake pedal did just as you described. You could plug the line going to your front brakes to see if this improves your pedal. I also have used framing squares on the rotor and bracket ears to see how far off the brackets are, it was obvious on mine. There have been other threads on this. See nova404's photobucket and you'll see my picture that resolved my issue.

 

[Nova 404]

 

[Vnova]

I'm gonna replace the bleeder screws with some speed bleeders but can't determine the size. I've used a 10mm wrench that fits. When I put my info on summit it only comes up with a 5/16 and 3/8. I thought it would be 10mm x 1.5. Are CPP calipers standard or metric?