73-76 A-Body Offset

[Duster_71]

Hello All,

I'm getting ready to convert my 74 Duster from Drum to Disc Front Brakes. What kinda, i.e., how much offset you guys running on your wheels? I'm currently running 15" Cragar SS with small bolt pattern and will be moving to 15" 4.5 bolt pattern. Is there a difference between the offset required for drums compared to disc or would they be the same?

Thanks.

v/r
Ron

 

[autoxcuda]

Max rim backspacing is 4.5" with stock upper control arms. With tubular A-arms you might be able to get 4.75" because they don't have a lip on the outside edge next to the rim.

The more backspace you can run on a 15" rim will give you more room for wider tires and rims in the front of an A-body. Typical setup for a 73-76 duster would be 15x7 4.25 backspacing rims with 215/60/15 tires. Many people run 225/60/15 tires and of course they will be closer to fender fitment. Alignment. and past vehicle repair can change clearances.

The offset calculation will vary on the rim width.

I've read that the 73-76 discs will push the rims out some. Don't remember the exact amount or if someone has truly made an accurate measurement of that.

 

[Beatnik]

If you want the rims/tires to tuck under the fenders and not "stick out" too bad, you'll need rims that give 2" or less on the front side (ie a 5" rim with 3.5" back spacing leaving 1.5" on the front side). I have the same set up, 73+ LBP discs with Firm Feel tubular uppers and run a 15x3.5" Weld Draglite with 1.375 backspacing and it looks decent. Still a little too far out to the fenders IMO. I'm thinking of changing to what I mentioned above a 5" Draglite with 3.5" backspacing to help pull them in a touch more 1/2" or so. Tough though because the conversion does push the track width out considerably.

That being said, I've run a 15x7 cop wheel with 4.25" backspacing and a 225/70/15 tire and it fit but rubbed at full lock backing up a bit. That was a temp combo tho and it was pushed out to the fender lips quite a bit. It was wider than my rear track width too, which I'm also trying to avoid, but again it's tough because I like my rears inward a bit too not sticking out or right on the quarter lips! If you like the 70's stink but stance and fatties sticking out past the qtr lips you won't have an issue there!

 

[Blacksheep]

I have a 73 Dart Swinger that is all stock with LBP 5x4.5 American Racing Outlaw IIs that are 14 inch with 205/65R14 all around. I want to run 15 or 16 inch. I'd run 235/65R15 on rear and 225/65 R15 up front if i go with 15s. Anyone running 16s? If so what sizes would you recomend? Thanks for any help!