I installed 4-wheel disc brakes on my '61 with parts from Master Brakes. The problem is that it takes a huge amount of pressure on the pedal to stop the car.

I took the car to the local brake shop and was told that I needed a larger bore master cylinder to make it work. This creates a problem with hood clearance unless there is a big bore master cylinder that has a low profile.

Has anyone else had this problem and is there a solution????

The brakes work, but not as they should. I do not have a power booster on it, since I don't think the booster would clear the hood either, even the 7" variety.

Any help resolving this problem would be appreciated

 

First off, I would contact Master (Power?) Brakes and ask for their help.

Secondly, the guy who told you that you need a larger bore master cylinder for more effective pressure (to the wheel calipers) is incorrect. A smaller bore master cylinder will result in a higher effective pressure (assuming all other factors such as brake pedal leverage remains the same), but at the expense of a longer pedal travel (smaller bore displaces less fluid, so the piston has to move further to make up the difference).

I have the most common aftermarket type disc brake caliper setup on my 62 (fronts only, drums are still on the rear). Those are the typical 70ish Chevy (Camaro, Monte Carlo, and the big Chevy's all used them) single piston calipers. I used the stock master (original single piston), and it stops great. A friend of mine has 4 wheel discs (fronts are C2/C3 calipers, rears are mid 80's Caddy rears), and he is also running the original master, and it stops great as well. So I doubt that the master bore size is an issue (if it was, I would of expected Master Brakes to indicate so). Even if it was an issue, changing bore size a great deal (and from your description it would need to be changed greatly - if that is the problem), then pedal throw would become an even a bigger issue!

What calipers are you running, and do you still have the original master cylinder (and if not, what master do you have?). Did you install any additional items, such as a proportioning valve or metering valve? Did you remove the metering valve from the original master? Lot's of questions here! Need more info before we can try to help further.

Plasticman

 

A LARGER bore master cylinder will require MORE pedal pressure to stop your car. A SMALLER bore will require LESS. I don't know anything about Master Brakes or what they sell. If they are supplying mid-year Corvette calipers,a one inch cylinder should work and you could use the '65-'66 OEM master cylinder. You could even go to 7/8's for even less pedal pressure using a cylinder from early-mid '60's Chevrolet,Chevelle, Camaro, Chevy II or Corvair. You wouldn't have the larger reservoir of the '65/'66 factory disc brake set up but I'm not sure it's necessary if you keep the fluid level topped off.

It's just a stab in the dark unless you can tell us what you have in the way of calipers and master cylinder.