Drum brake swap from 7 1/4" to Jeep 8 1/4"

Charrlie_S said

What 8 3/4?
An "A" body 8 3/4 will be 4 inch SBP and the small drum center hole. The 7 1/4 BBP 10 inch drums will be 4 1/2 inch BBP and large center hole.
The BBP 7 1/4 backing plates do have 5 holes and I think they are the same pattern as the "A" body 8 3/4 (I don't have a 8 3/4 backing plate that I can measure). I do have small and large bolt patten 9 and 10 inch parts I can measure.

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I really didn't word that well, now that I re-read it....lol. First one was when I swapped from the factory 7 1/4 BBP rearend in a 71 Challenger to a factory E body 8 3/4 housing. I removed the axles from the 7 1/4, removed the backing plates and lines from the 7 1/4 and suspended the brakes in mid air without cracking the lines. I removed the old 7 1/4 housing and installed the 8 3/4 housing, put the backing plates back onto it with new seals and installed and adjusted the axles. It all fit back perfectly.

The other one was when I swapped BBP 10" drums from a junked 7 1/4 to an 8 3/4 housing cut to A body length and a set of Dr. Diff BBP axles for stock A body length. The backing plate offset is the same on BBP 7 1/4 brakes as it is on the BBP 8 3/4 brakes. I have a few sets laying around from where I junked out a couple of more door 318, 74 model Valiants years ago.