An accurate 8 3/4" rear axle width list
I have a slant six car and am changing to v8 car with 8.75. 8.75 "A body" rear end is currently sbp, changing to bbp. I'm trying to figure out backspacing for wheel without converting to bbp and disc setup and the having to possibly cut axle down. I want to run 6.38 BS. Car is completely torn down, going to mini tub and cut lip of rear quarter and possibly roll. Also have 3/4" shackle offset. Want to run a 295/40r18. Any help would be appreciated
So, is this for a '68 Barracuda like your screen name would suggest?
If it is, you're basically going to be running the same set up as I am with my Duster, except with a BBP A-body 8 3/4 in place of the B-body 8 3/4 I run. Assuming you're looking at an 18x10 for a rim, it's just correcting for the axle width change because the wheel houses are pretty much the same and we both have offset springs. The 18x10's I run have a 7" backspace, but I run them with drums at the moment. The B-body 8 3/4 I run puts the wheels out about 1.15" further than a BBP A body 8 3/4, so, you'd be looking at 5.85" of backspace to put the tires in the same spot. Most disk kits add 5/16" to 3/8" per side for width, so, add that in and figure about 6.15"- 6.22" depending on the disk kit.
Which means 6.38" is pretty darn close. More than likely you'll need a small wheel spacer to make it work, you'd be looking at about a 1/4" spacer. But that's assuming everything is identically the same, which is won't be. Bottom line is you'll have to measure your own car, but an 18x10 with 6.38" of backspace with the offset springs and a quarter lip trim should be in the ballpark with 295/40/18's with a BBP A-body 8 3/4 with rear disks if you run some kind of small spacer.
295/40/18's are about as tight a fit as you can make it, so, you will definitely need to make your own measurements and plan on making some adjustments to get the clearance you need. Feel free to send me a message if you want so we don't sidetrack this thread.
