1st gen f-bdy, running 2nd gen f-bdy rear

[PoundinPoncho]

Hey guys, I recently picked up a 79 Z-28 10 bolt posi rear end w/3:42 gears. I plan to run this rear end under my 68 Firebird. The second gen rear is a little wider than the original, so my question is,,,, what size wheel backspacing and tire will fit into the stock wheel wells. I am looking into possible 18s later on in the rear. I currently have Torq thrust D 15" and also have a set of Trans am GTA wheels 16". If you have any insight or knowledge regarding how much backspacing I can handle, the information will be greatly appreciated. Thanks

[Tom Welch]

Mount it on the car and measure from the axle flange to the inner wheel well and then to the outer wheel lip. this will provide the limits of what you have to work with, subtract about 1" from inside and outside measurements. The number that you get will be very close to the desired wheel width. using this info you can calculate the correct offset. Measure as many times as it takes to be confident in your numbers before you order your wheels.

[cad]

I have a Gen 2 camaro rear in my 68. It has been a long time since I have measured. I believe my 15x8 billet wheels (early 90s) have 5" back space with zero issues. I think we had to move the leaf spring mounts in on both sides. Matter of fact, I know we did. I think it is 3/4" wider overall. So, instead of the old tried and true 4.5" backspace, I am able to run as much as 5" backspace. I am running Weld drag wheels now - so I apologize if this is way off compared to running the plus sized wheels.

[68Formula]

I have a Gen 2 camaro rear in my 68. It has been a long time since I have measured. I believe my 15x8 billet wheels (early 90s) have 5" back space with zero issues. I think we had to move the leaf spring mounts in on both sides. Matter of fact, I know we did. I think it is 3/4" wider overall. So, instead of the old tried and true 4.5" backspace, I am able to run as much as 5" backspace. I am running Weld drag wheels now - so I apologize if this is way off compared to running the plus sized wheels.

Disc or drums? Can make a difference.

[cad]

Drums.