Brake Question

[gmracing355]

I just changed my brakes on my 72 nova from a all drum setup to areospace discs in the front and drums in the rear with a 72 nova 1 1/8 bore master cylinder. The pedal is solid but there is no brake pressure to hold the car against the converter at the line. I noticed on the brake pedal there is two mounting holes for the brake pedal push rod. Mine is mounted in the top but should it be in the lower hole for more pedal ratio to help with pedal pressure???? Help,lol
Greg

[sc68z28]

Mine is mounted in the top but should it be in the lower hole for more pedal ratio to help with pedal pressure???? Help,lol
Greg

Greg, I'm pretty sure the top hole gives you the most leverage, I'd leave it there.
A smaller bore master cyl would give you more line psessure.

---Bill.

[dadnova]

I agree with Bill as far as the top hole,
Top hole more pressure due to leverage
Bottom hole more volume, less pressure
I disagree though on a smaller bore, I don't see how that will increase pressure much, if at all.

My thoughts are this, did you also install a proportioning valve?? Remember, Drum brakes take more fluid then Disk brakes, you now have two types of brakes, the booster does not know it, nor can it adjust for it.
Just my thoughts.

[sc68z28]

Here's a good read on brake lever and master sizing.

http://www.markwilliams.com/braketech.aspx

---Bill.

[ccjohn2]

When I had the stock GM disc brakes on the front and stock drums on the rear I was able to get away with the smaller bore master cylinder. Now that I have aerospace front and strange rear discs I had to go to the larger bore master cyl because of the extra vol need to push the pucks out. You may need to increase your bore size also. CJay