There has been plenty of discussion on how well stock '40-'48 Ford brakes work. I've read and heard claims that "they will put you through the window" and there are "no problems running at highway speed". Well...frankly...I don't care. The fact of the matter is that I am not satisfied with them. I've built the '40 to be capable of running 70 mph all day long and its time that it can safely stop from those speeds. I've tweeked, adjusted, and manipulated them long enough. It's time to embrace technology and move up several decades in braking evolution.
A disc brake conversion was my original idea of an upgrade however, this presented a couple of issues. First of all, I wanted to use my 15" Ford wheels that have a 5 on 5 1/2" bolt pattern.
The commercially available kits for the 5 on 5 1/2" bolt pattern use newer F150 rotors. When adapted to the '37-'40 spindles, they tend to push the tire out about an 1/2". With the truck sitting a low as it does, I feared that I would have a clearance issue with the fender if the tire moved out any more that where it was. The second issue is that the caliper would not clear the stock 15" wheels. A disc brake wheel is different than a drum brake wheel on the inboard side as it is configured with more clearance for the caliper. So, any commercially available kits were simply not going to work.
I looked at making my own disc conversion using hat style rotors off of a 4x4 jeep. This would only push the tire out a 1/4"', but I still would have caliper clearance issues. It was at this time that I ran across a complete '56 Ford F100 truck front end at an auction. It was complete from drum to drum and in excellent shape. So, I bought it for scrape price and drug it home.
The '53-'56 F100 not only used self energizing brakes, but the backing plates shared the same bolt pattern as my '40 spindles. This was a fairly common swap back before the many aftermarket options currently available. The brakes are 11" in diameter compared to the original 12" but they are 2" wide compared to the original 1 3/4" wide shoes of the '40. The F100 brakes are not self adjusting but the self adjusters from a '65-'66 F100 fit with very little modification.
So to start, the original brakes had to go...
Here is a good side by side pic of the original 12" '40 ford brakes on the right and the "new" F100 brakes on the left with the self adjusters mocked in place.