72 dart backspacing question

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txbullets

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I have a 72 dart swinger. I am putting a 340 in it and I have purchased an A body 8.75 rear end with 5x4 bolt pattern. I am considering my options here and going to a swap meet this weekend so want to keep an eye out for wheels.

Option 1: keep the 5x4 bp and be limited on wheels.

Option 2: keep the axels and buy a 5x4 to 5x4.5 converter.

Option 3: buy new axels and just go 5x4.5

My questions start with if I want to run a 7" or 8" wheel what backspacing do I need for each option. I am sure option 1 and 3 will be the same but if the converter in option 2 is 1" thick do I add or subtract an inch and how hard will those wheels be to find. I am very much a noob when it comes to this. Also I have read where many people have used spacers. Is that something I will need to look into with each option.

Fwiw I am not sure what wheels I want yet. Nothing is jumping out at me. Probably looking at a 15" rim.

Thanks in advance!
 
Option 1 and 3 will not be the same unless you get custom axles to reuse the small brakes and reuse/drill the drums. Otherwise most off the shelf LBP conversion axles use the wider lbp drums. I needed a 17x8 with 5.375" offset to fit 245-45-17 under my 69, your 72 will have a more room in the front and rear than the 67-69 Darts. Now if you go LBP front conversion as well this adds to the offset too. I went with a 17x7 x 4.75 as well.

This is a good read

http://www.forabodiesonly.com/mopar/showthread.php?t=225071

To sum it up, if you change to LBP, you'll need a more posative offset (i.e. more back spacing) wheel, front and rear depending on what you decide to do.
 
FWIW, I had SBP 15x8.5 Centerlines on my car (68 cuda) when I got it. They had 4-7/8" B.S. with 255-60 x 15's. The inside of the tires just kissed the leaf springs. A single 5/16" wheel spacer gave it just enough clearance. Those are the numbers that gave zero clearance from tire bulge to leaf spring on my car with an A-body 8-3/4" and stock location springs.

If you stay SBP A-body 8-3/4", a 4-1/2" B.S. should be OK. You will have to determine what rim width will fit though. 7" should be good, 8" ? A 72 Swinger has narrower wheel wells than a 68 cuda.

Later I had C-body axles shortened by Moser to A-body length. With B-body 10 x 2-1/2" drums, the dimension to the drum surface increased exactly 3/8" per side. (I plumb-bobbed to the concrete floor before and after the conversion) I'm using Mopar 17 x 7 steelies and all the Mopar steelies have 4-1/4" B.S. These are actual measurements I'm using.

I wish I could remember the aftermarket wheel mfr that makes a decent assortment of SBP wheels but I'm drawing a blank.

Your results may vary. Chrysler said 1/2" variance side-to-side or car-to-car is acceptable. Best bet is to find someone with a similar car, rear end, etc. and see what worked for them.
 
OK so if I decide not to change anything I will most likely go with Coy wheels because I like the look and they offer 5x4 bolt pattern. I am considering that or

In a 15" wheel the 15x8 comes in a 4", 4.5" and 4.75" back spacing. Guessing I would need to go with 4.75 if I keep my a body 8 3/4 rear end as is. Is that correct.

The 15x7 only comes in 4" backspacing. Will that work on the front or would I need to go to a 15x6 which has 3.5" backspacing?

Basically I am trying to decide if I want to keep it as is or start making changes to allow me to run a little bigger tire.
 
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