moser axles
so if i put the b body offset axles in a 68 barracuda and use the b brakes what backspacing and offset would i need to run on the new wheels? was also thinking of relocating the springs to fit a wider tire. not sure of where to start on sizes.
I converted to BBP in my 68 cuda maybe 5 years ago. I sent C body axles to Moser via UPS and had them shortened. The VERY NEXT morning, they called me at work to confirm what my plans were. I told them I was using 69 B body backing plates and 10 x 2-1/2 brakes. They shortened and resplined the axles and I had them a few days later. (new length was exactly 28")
I installed them in the stock width A body 8-3/4 rear end. Before removing the a body axles and stock 10 x 1-3/4 brakes, I plumb-bobbed the outside face of the stock axles to the garage floor and made a mark. The shortened C body axles added exactly 3/8" to the track width on each side compared to the stock a body 8-3/4". You can book that dimension cause I carefully measured it.
I had 15 x 8-1/2 SBP Centerlines (4-78" B.S.)before the change w/ 255/60 tires. The inside side wall of the tire just touched the spring so the previous owner had 5/16" spacers in there to provide clearance.
Depending on what you are trying to do, what tire/wheel you end up with, what car you are working with, etc. Your back space will vary but if you do not relocate the springs, 4-1/2" should be safe. I'm now running 15 x 7 original Mopar steelies on all 4 and the backspace on those is 4-1/4".
Whatever you do, you MUST match the backing plates to the brakes! There is an offset built into the backing plates to compensate for the shoe width. For instance, you cannot use 1-3/4" backing plates with 2-1/2" shoes.
In my opinion, (not that anyone asked) 11" drum brakes on the rear of an a body are overkill. And the extra rotating mass will definitely make your car slower. Physics don't lie.
