Brake issues on power brake update.
 

I have a 64 SWB C10 with brake issues. It has a 5 lug conversion, with disc front/ drum rear, but was non power. I recently installed a new dual booster/ master cylinder unit from CPP. I have good vacuum and the check valve is working properly. When I brake for regular stop and go traffic I have decent stopping. But at highway speeds or on hard braking, I have to stand on the pedal and hope I can get it to stop. It is as if I didn't have power brakes at all.
I am at loss on where to go now. Any ideas would be appreciated.

Re: Brake issues on power brake update.
 

How is your vacuum to your booster,where are you pulling your vacuum from? Is the check valve good? Did you re drill your brake pedal?

Re: Brake issues on power brake update.
 

What is the diameter of the booster? And is it a dual diaphragm or single. The smaller the diameter of the booster, the less braking assist you will have. How much vacuum does your engine produce?

Re: Brake issues on power brake update.
 

Do you know what the diameter of the brake cylinder is? Inside the master cylinder.
What size are your brake lines?

Re: Brake issues on power brake update.
 

Try adjusting the pedal rod under the dash, I struggled and struggled with mine until I adjusted it to engage sooner.

Re: Brake issues on power brake update.
 

Wait a minute, I have manual disc and I have never had to stand on the pedal and hope I can get it to stop at highway speeds or under hard braking. Is it possible that you already had some issues prior to adding the booster?

Re: Brake issues on power brake update.
 

Also have you done the pedal ratio correct when you went to power disc?

Re: Brake issues on power brake update.
 

I never did it on my 66. I left it in the same hole.