Originally Posted by Holdon
I have just been in touch with Willwood as their website said they do a disc brake conversion kit for a 57 Oldsmobile 88, turns out they only do the back and not the front, ridiculous! All I am looking for is a disc rotor that will fit onto the Oldsmobile stub axle, getting a caliper to fit will be the easy part! Does anybody know of any other model with the same size stub axle???
All you need is a rotor that fits a 5 x 5" bolt circle, with a center pilot that is close enough that you can machine either the rotor or the hub to fit. As noted, many of the FWD GM large cars in the 1970s and 1980s had rear rotors that should work on your front hubs. Check a late 70s Toronado or Eldorado with rear discs. Here are the dimensions for a 1977 Eldo rear rotor: