Mopar Action On-line – Tech Questions
Rob Jock, Morristown, NY, 1969 Plymouth Belvedere 5.7
I am converting a slant 6 car into a modern Hemi and I want to put a 9¼” sure grip rear in it. Are there any that fit my B body? If I get a truck rear with disc brakes can I still use the discs when I have it shortened and buy axles with 5 on 4½” bolt pattern for it?
Even the ones from a 71-up B-body will be too wide. You might want to check 2G Daks (and Durangos), I can’t think of anything narrower that came with a 9¼”. The advantage to using that rear axle is that the center register (for the rotors and wheels) is the same as our “classic” Mopars – 2?” (‘prox.). So, even though you’ll probably still have to narrow the whole deal (and get custom axles), the disc brakes will be simplified — most likely, you could get away with the stock rotors (just drill 4 new holes – the bolt circle is 4.5″, but it is 6 lug).
You might also want to check ’70s – early ’80s D-trucks, the bolt pattern was 5×4½” – but you’d need aftermarket discs (or ’70s Imperial, but parts availability sucks), and you’d probably still need to have it narrowed.
No matter which axle you wind up with, you’ll need to buy new perches (spring seats) and set the pinion angle once it is bolted together, then weld them to the housing.
Be sure the new axles you buy are thick enough in the pilot area to center both the rotors and the wheels.