[jamaca85]

switching to manual brakes just wondering what I need? I got a manual brakes pedal rod . Can I reuse my old master? its in a 70 firebird and the brake pedal has the extra hole on top that I can use where the brake switch goes. I am looking and want to know what will hold the brake rod in the master cylinder to keep it from falling out? thanks

[JLMounce]

Switching from power brakes to manual, you're likely going to want to change the master cylinder. Although a power master cylinder can be made to work, you likely want a different bore size and to your statement, you need to figure out a way to keep the rod in place. Many manual masters will have the rod physically attached. The power master also may not have a strong enough internal spring to return the brake pedal, you may need to affix a brake pedal return spring.

I would look at a 15/16" master cylinder designed for manual brakes instead of trying to engineer something with what you have. More than likely you have a 1" bore master, but you could have a 1.125" bore master. If it's the larger, that's going to require very heavy pedal effort to get the car to stop. With manual you want to take advantage of the smaller bore to help with pedal effort. You trade off with longer pedal travel.

[jamaca85]

I got it all in there. the pedal sits just about the same height as with the power booster installed. I used a stock manual brake rod. the pedal comes back up. it was pretty easy ...

[b-man]

I used a 1970 Firebird 1” bore manual disc brake master in my ‘64 Le Mans and it’s great, I have ‘69 GP 11” discs and stock rear drums.

[AG]

Originally Posted by JLMounce

Switching from power brakes to manual, you're likely going to want to change the master cylinder. Although a power master cylinder can be made to work, you likely want a different bore size and to your statement, you need to figure out a way to keep the rod in place. Many manual masters will have the rod physically attached. The power master also may not have a strong enough internal spring to return the brake pedal, you may need to affix a brake pedal return spring.

I would look at a 15/16" master cylinder designed for manual brakes instead of trying to engineer something with what you have. More than likely you have a 1" bore master, but you could have a 1.125" bore master. If it's the larger, that's going to require very heavy pedal effort to get the car to stop. With manual you want to take advantage of the smaller bore to help with pedal effort. You trade off with longer pedal travel.

This is good advice. If you use D52 calipers a 1" might be needed for the extra volume.