I converted my 48 to 4 wheel disk brakes using Cadillac Eldorado rear calipers with the parking brake. What a **** poor design. Had trouble figureing out why I did not have good pedal pressure then I did some research on these rear calipers. These calipers are adjusted with the parking brake and they do not bleed like normal calipers. They must be gravity bled and the parking brake hooked up in order to get them bleed out. When mounted on the axle the bleed screw is not at the high point and leaves an air pocket in the piston and all that you get is a spongy pedal. It took a while to figure this out but now I finally have a solid brake pedal.

 

They also require the park brake to be used periodically to keep them adjusted up as they don't self adjust.