48-52 F1 and 53-56 Ford F100 Front Disc Brake Conversion Kit. FORD (5-1/2) Bolt Circle – uses 73-93 Ford F100/F150 (2WD) rotors with 71-79 GM big car calipers. Our Early Ford disc brake conversion kits are engineered and designed to bolt on to your stock (or repro) Ford spindle. Absolutely no machine work is required. Installation is accomplished using simple hand tools and the components supplied in the kit. Complete instructions are provided. Disc Brake Kits are available as either a basic kit or as a complete kit so you don’t have to hunt around for parts. Basic kits: include caliper mounting brackets, attaching hardware, and bearing adapters where required. Fits 48-52 Ford F1 and 53-56 Ford F100.