F body 16 in wheels-what is the backspacing difference?

[85 Cutlass Brougham]

I am wondering what the difference in backspacing is between the front and rear 16x8 inch wheels used on 3rd gen F bodies like the IROC-Z and Trans Am GTA. I know the rears and fronts are different, but I am thinking of using a set with the rears in the front and B car spindles. There is WAY more to this (I am working on re-engineering the front suspension geometry), but for now I would appreciate it if someone who knows the difference exactly to post it here.

(I am trying to keep the same basic look my car has now when I change wheels, and that is why I want to use these. Try as I have, I can't find anything that would look better. The gold mesh 80's look wheels just sort of make the car. Why not keep the ones I have? Three are bent, one is missing the center cap, and they really need to be refinished. I figure I can find the GTA wheels easier than the Enkeis.)

 

[Jman]

found this on the thirdgen site. 16-inch: 16x8 with 4 1/2-inch backspacing front, 5 1/8 backspacing rear.

 

[khan0165]

I don't believe that's correct, unless the GTA 16" wheels are different from the IROC 16"

the IROC 16"s have
4.75" Front
5.25" Rear

you need to run them reveresed on a G-Body
ie: Front in Rear, and Rear in Front

you may also need spacers... I have a 1" spacer for the front disks, and a 3/8" spacer for the rear drums.
With the rear drum however, I am using extended studs, 2-7/8" long. Normal studs will not be long enough. And, at this point, it may be worth it to buy adaptors to take the guess work out of it. It'll also give the back your car a nice stance.

 

[85 Cutlass Brougham]

Well, the B body spindles with 1LE rotors pushes the fronts out 3/8 of an inch, and I figure this will let me run wider fronts by pushing them in a little if I use the rears up front. I will also be using a F body steering box off an IROC Z for the thicker steering stops to limit travel. As for the rears... Hmmm... I thought the F car used a 4 inch backspacing. I may have to do a bit more math before I buy anything. If I could find a pair of Enkei 92's that are straight, 16x8, have a 5x4.75 in Bolt circle and have a 4.5 or 4.75 in backspacing, it would solve all my problems too.

 

[79GP6.6L]

Would this help? Classic Industries sells the 16x8 GTA wheels.

http://www.classicindustries.com/co...st=&productId=120744&productSearchCatalogId=3

http://www.classicindustries.com/co...st=&productId=120745&productSearchCatalogId=3

 

[79GP6.6L]

Their catalog says they take off $100 if you buy a set of four.

 

[78 Green Lemans]

I measured my Irocs yesterday...............

Fronts 4.5" backspacing
Rears 5.25" Backspacing

depending on how wide and tall of a tire you are wanting to run and how your tail pipes are done a minimum of 0.75" spacer will be needed 1"-1.25" would be much better.
For my set up thanks to the dumbass exhaust guy 1.25" is best and 1" will only work if i run a very low pro tire.
I have not tried the front ones yet.