Here is a drawing I made of the measurements taken on Aaron's '74 Duster project we are building. This is a stock '69 B-body 8-3/4" rearend (not narrowed and perches not moved in), with American Racing Torque Thrust II 15"x8" rims and 235-60R15 BF Goodrich T/A Radial tires.
The goal is to move the wheel inboard to gain more clearance at the outer lip of the wheel well. You can see that the limiting factor will be the leaf springs. Obviously, relocating the perches the necessary 1/2" on this A-body installation would help, but we aren't going to do that right now. If I understand backspacing and offset correctly, I would say this wheel has 3-3/4" backspacing, as noted in the sketch.
Can I safely assume that leaving 1/2" clearance from the tire's outer wall to the springs is sufficient? If so, that means I could move the wheel inboard 1-3/4", increasing the backspacing on a new wheel to 5.50".
Comments?
The goal is to move the wheel inboard to gain more clearance at the outer lip of the wheel well. You can see that the limiting factor will be the leaf springs. Obviously, relocating the perches the necessary 1/2" on this A-body installation would help, but we aren't going to do that right now. If I understand backspacing and offset correctly, I would say this wheel has 3-3/4" backspacing, as noted in the sketch.
Can I safely assume that leaving 1/2" clearance from the tire's outer wall to the springs is sufficient? If so, that means I could move the wheel inboard 1-3/4", increasing the backspacing on a new wheel to 5.50".
Comments?