The Stovebolt Site Forums The Shop Area Driveline Opinions on converting to S10 Master Cylinder with booster

I have a 1946 Chevy 1/2 ton. I converted the front with a disc brake kit and running Bendix brakes on the back. This truck will just be a cruiser and not pulling any weight. I have an old mid 80's Chevy S10 with dual MC w/ 1" bore, booster, and proportioning valve out of the junkyard. Disclaimer: I'm not a mechanic but a tinkerer and learning as I go. Any opinions with this setup. I have already cut holes and put in the pedals with bracket in the truck. Wondering if I should go with a single bore or manual brakes from what others have commented. Any advice is very appreciated.

If you decide to go with the dual piston M/C, be sure and use the entire system- - - -proportioning valve, etc. The only advantage to a dual chamber M/C is redundancy- - - -in the very unlikely case of a leak at one end of the vehicle, you'll still have half a brake system, but with an EXTREMELY low pedal height. I think I'd rather keep the single M/C with a small diameter booster, one that will fit close to the original M/C position under the floor.
Jerry

I had an S10 master and booster but it was from a '90's version and had a stepped bore. While my system is different than yours I found that in my case the rear brakes would lock up with medium to heavy brake pedal effort. I changed to a staight bore master with an adjustable proportioning valve to get my rear brake pressure under control.

Under the floor is not an option at this point. I've decided I don't want to fight checking my MC under the floor and have already drilled the holes for the firewall mount. What metrics should I be looking at to have enough braking power? I have installed a 350 with 700R4. My front disc brakes single pistons are 2.5 inches in diameter and the rear wheel cylinders are 1 inch. Any reason why the step bore wouldn't work in this situation before trying it? Are the mounting holes the same from the S10 booster I have to an aftermarket single bore?

My front disk brake conversion has 2.953 (75mm) pistons and my rear axle (14-bolt) has 1.1875" wheel cylinders. I have not really tested the braking power and hopefully never will need to. Given your intended use I suspect your brake calipers and rear pistons will be up to the task but others with real insight may have a better idea.

I did not have trouble finding options for master cylinders that would fit the S10 booster bolt pattern. In my case the S10 stepped bore master may have been fine but the S10 proportioning valve was not and resulted in rear wheel lock up with medium to high pedal pressures. I decided to jump to the straight bore and manual proportioning valve (for the rear) to avoid multiple iterations.

I appreciate the input gentlemen. I will give it college try and see what happens.

Regardless of which M/C you choose, be sure to reinforce the mounting location on the firewall. There is a lot of pressure and fatigue on the mounts.

Thanks for the advice. I had a donor cab since I had to replace the rusted out brow on my build. I just cut out the stamped firewall and mated it to my firewall and will brace more if necessary from the pedal bracket.