Hot Rods Drum brake question

I have built a 29 Ford model A coupe and I have 58 Buick drums with 48 Ford backing plates and hardware on the front. The rear brakes are a stock style drums from a 76 maverick. The MC and pedal is the one sold by Speedway motors for a model A/T set up/ for under the floor, it comes with a MC from a 65 mustang I believe. 6:1 pedal ratio, I think. I have the proper residual valves inline for both the front and rear.
The problem is that the brakes are harder than a rock and don't provide much for stopping power, anyone have any thoughts on why this is?

 

Size of the m/c bore?

 

1" bore

 

I'm assuming this is a new set-up and you have made sure everything is working mechanically and hydraulic wise; pull a front and rear drum and see what the shoe contact looks like.
Maybe the shoes need to be arced.

 

Is your push rod adjusted correctly
If it’s tight it won’t let the fluid return and you get a hard pedal.

if the drums are used and heavily glazed you get the same thing.

pull the drums and get someone to step on the pedal and see if everything is moving and returning correctly.

see if you can see how and where the shoes are contacting the drums.

 

Isn't a 65 Mustang master a single reservoir? Are you sure of what you have?

 

Are the residual valves you added put in pointing in the correct direction? With drum drum brakes you may not need to ad residual pressure valves, the master cylinder may have them installed in the ports of the master cylinder from the factory.

 

Sounds like you have pedal but its not stopping. The issue might be in the new linings not being worn in to the curve of the drums.

A 1"bore is kind of big for manual but not unheard of.. Can you make the pedal longer to give more leverage..

 

Make sure you have the primary and secondary shoes in the right spot. That is the long shoe to the back.






Bones

 

The '48 Ford Lockheed brakes he has on the front have the long shoe in the front and the short one to the rear; unless he has some of the new repops where they made both shoes the same length. I also hear that some of those repops have hard linings.

 

Then that may be the problem! He may have assembled like I would have! Do you know why they did that? Most of my experience was in later model drum brakes and every one I ever ran into had the long on the rear or were of equal size.





Bones

 

MC's bore is too big. With a 6-1 pedal and a 3/4" or 7/8", it should feel like power brakes in a light car like what you have