8.75 narrowing in a 72 dart

Suspension, Steering and Chassis

  1. Phillip Tillman

    Phillip Tillman Member

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    I am relocating my springs to the inside with mopar relocation kit. What width should the rear end be
     
  2. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    Whatever width it needs to be to center your choice of wheels in the wheel well.

    Seriously, your best bet is to figure out what wheels you want to run and what backspace they come in and work from those to determine the width. For 15” rims a narrowed rear axle works great. If you’re looking at 17’s, 18’s or larger a narrowed rear axle may actually be a hindrance.
     
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    • abodyjim

      abodyjim Well-Known Member

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      Now that's impossible to answer without several other inputs. You need to decide if you are mini tubing or not. What look are you after(pro street or pro touring). You start pricing wheels for the offset/backspace you need and you'll understand that. So wheels and tires, what rearend is in it and what brakes are gonna be used. And if you lower the car that has an effect on how close to the quarter you can be.
      All that aside I have a 8.75 housing narrowed to 46" flange to flange and I believe i can do a 10" wheel with a 4.5" backspace if it's mini tubed in a 71 dart. That is a rough measurement i did looking at doing a pro street setup.
       
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      • Phillip Tillman

        Phillip Tillman Member

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      • Phillip Tillman

        Phillip Tillman Member

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        Thank you the rear end is a 8.75 with 489 case and 4.10 with truetrac, it is already narrowed to 48 inches flange to flange. Will have disc brakes. Trying to figure what size tire will fit under it with a mini tub.
         
      • moparmat2000

        moparmat2000 FABO Gold Member FABO Gold Member

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        If that's a stock width A body 8.75 and you plan on cutting it down, I have a C body 8.75 housing I will trade you that you can cut down. A body 8.75s are hard to find stock width unbutchered.
         
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        • abodyjim

          abodyjim Well-Known Member

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          That's probably a pretty good width. Not sure what the disks will do but id guess push the wheels out. If it measures out around 5.5" backspace you should be able to find wheels at a decent price and size for what ever style you want but it will take some measuring. Do you have the axles?
          My measurements make me think i can use a 295/65/15. I have them already but I think the 295/55/15 would fit better.
           
          Last edited: Mar 18, 2020
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          • abodyjim

            abodyjim Well-Known Member

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            The rearend is almost 5" narrower than a stock abody
             
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            • Dragonsteel

              Dragonsteel Well-Known Member

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              What would be the hinderance? I have a stock width A-body 8 3/4 under my 71' dart running 18" x 10" wheels with a Right Stuff disk brake kit with mini tub and had to get a custom 6 1/2" back spaced wheel to get them inside the wheel well and it's so close you cant get a finger between the tire and the wheel lip. A 1" to 1 1/2" narrowed axle would have been a better way to go, I just have to be careful on the cloverleafs and traffic circles, straight line is fine.
               
            • 72bluNblu

              72bluNblu FABO Gold Member FABO Gold Member

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              And my off the shelf 18x10’s have a 7” backspace, and there are off the shelf wheels out there with more.

              Like I said, it’s better to pick the wheels first. Lots of 17” and 18” wheels are available with a significant amount of backspace, so it’s totally possible to narrow an axle too much and have to get custom wheels. But it depends on the wheel. If you’re doing a custom width rear axle it just makes sense to make it a width that you can use the off the shelf wheels you want.
               
            • famous bob

              famous bob mopar misfit

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              thumbnail.jpg 295 60 d15 , no rub, not sticking out, just a 3/4'' offset spring hangar kit , and a stretched front wheel opening '' before paint ''.
               
            • Phillip Tillman

              Phillip Tillman Member

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              I have the axles that came out of the rear end but they are not usable be cause of condition. I'm going to get after market axles more than likely Moser. The axles i have came with the rear end that was already narrowed
               
            • Slowswinger

              Slowswinger Well-Known Member

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              I pondered the same thing for the same year car. Do the mini tub first and center the wheels/tires you plan to use. Then measure and subtract for your disk setup. A flange to flange measurement that worked for someone else may not work on your car and cause the added expense of custom offset wheels.

              Go to the Doctor Diff website for your housing ends, disk setup, and new axles. Dr Diff is a good guy to do business with and even answers his own phone.
               
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              • jefflock

                jefflock 69 Dart 408 10.008 best pass so far

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                Mopar in post #6 talks about saving stock width A body rear ends. I narrowed a wider rear end and saved the stock width A body rear end
                 
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                • oi81b4uu812b4

                  oi81b4uu812b4 Well-Known Member

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                  At 48" you need to add 2.525" twice for axle gap (axle flange to housing flange) and .188" twice for the disc brakes... so your width should be around 53.425" disc to disc.
                   
                • Phillip Tillman

                  Phillip Tillman Member

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                  Thank you that should help me measure for the wright size tire that I can fit in the wheel well.
                   
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