Hey everyone I could use some help. I am moving the leaf springs inboard 3 inches on my 70 Charger and I wanted to know for the people who have done it how much they shortened their axles tubes and axles ? I am running a 31 x 13.5 or a 30 x 14.5 tire on a 15 x 12 rim.

Moving the boxes and springs does not mean you have to shorten the rear end. It just means you can run a wider wheel/tire with more backspacing. And its worth pointing out that you will gain very little without mini-tubbing the car.

Back to narrowing the rear ... I recently moved the springs inboard and mini-tubbed the car. I only put a 2" strip in the tubs so they don't sit against the side of the frame rails. BIG MISTAKE as the widest tire available that will fit is only 13" wide at the cross section. If I'd gone all the way to the frame (and extra 1") I could have fit 15's in there. Had I done that I would have been able to use a wider wheel and I likely would have narrowed the rear 2" per side. Instead, I had it narrowed 1/2" per side only to give me adequate clearance at the wheel lip.

My advice is to decide on your wheel/tire size combo. If you're not going to mini tub the car, check out available tire sizes because what you need or want may not exist. Do a lot of measuring of where things will be with the springs moved. Draw pictures. Then decide on the axle width. This is not something you want to get wrong so using a measurement someone else used on theirs is NOT the way to do this.

Mine has rhe frame rail dlange timmed flush. Along with a slight trim of the upper wheel lip. it clears 15.5" section width. I agree start with the tire and wheel you are going to use first.
Doug

On my 65 Coronet, I used the USCT package for the spring relocation and mini tubs. Diff housing is stock width but I mover the perches in about 3" each side. When its time to get wheels, I'll use the tool I bought through Speedway and calculate offset of the wheel plus to see how much profile I can fun on the tires.