12 bolt rearend width

[njectd69]

Hey guys, I'd like to pick your brain about
what length rearend to put in my 69 camaro convertible.
I purchased DSE mini tubs and Quadra Link and now want to build a 12 bolt .The problem is I don't have the wheels yet to measure how wide to make the rearend.So I was hoping that some of you that has a similar set up done can tell me what width to make the rearend and what size wheels and offset would it take to get that
killer look and not have clearance problems.I probably won't go more than an 18 inch wheel for performance reasons.A 335 tire would be ideal ! Thanks

[chicane67]

FYI:
Factory OE, 12 bolt differential is 54.25". Individual axle length for a 12bolt is 29 - 9/16".

[Whistler]

My car is a 67 so the measurements will be off slightly.

I am running an 18x 12 in the back with a 345/30/18 drag radial
6 inch backspace, 56 1/8 axle flange to axle flange width.
Add on the discs and that gives a total 56 5/8 total rear width.

What I did: Order the wheels first in whatever offset you want, then stick them in the car on jackstands in the exact place you want them, then measure the width from axle flange to axle flange you need. Subtract a half inch for the width of two disc brake rotors and you have the width you need your axle.

Here's my car at ride height:


tucks nice when under compression

Here's the tool I made to measure axle width. Two 4th gen Camaro axles, with the splines cut off, slid inside a tube, with jamb bolts welded to the tube. Bolt the wheels to this dummy axle, roll them under the car, expand or contract the dummy axle, then tighten the jamb bolts and measure it.

[njectd69]

I screwed up

[njectd69]

Thanks chicane67, and Chris, by the way thats a great mock-up rearend ,it eliminates measurement errors and looks simple to make .