Got the new 9 inch from Doctor Diff

Engine, Trans & Driveline

  1. andyf

    andyf Well-Known Member

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    My new 9 inch assembly showed up the other day. It is a full Strange Engineering unit ordered from Doctor Diff. I went with the Pro nodular iron case with polished gears (3.89 ratio) S trac differential, bigger pinion support, billet 1350 yoke, fabricated housing, boxed mounts for the leaf springs, etc. I have 13 inch Baer brakes to install and then it will be ready to go under the car. This is the third rear end I've bought from Doctor Diff over the years and they always show up ready to go.
    DSC_4415 (Large).JPG DSC_4416 (Large).JPG
     
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    • Bee1971

      Bee1971 Well-Known Member

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      That’s a pretty rear end
       
    • yella71

      yella71 Well-Known Member

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      you own a ford?
       
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      • Stanton

        Stanton Well-Known Member

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        This is a Chrysler forum.
         
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        • yella71

          yella71 Well-Known Member

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          Yes. It is
           
        • Stanton

          Stanton Well-Known Member

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          not small block chevy ... LS !!!
           
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          • 5wndwcpe

            5wndwcpe Huge Member FBBO Gold Member

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            Andy, do you get to specify the pinion angle ?
             
          • andyf

            andyf Well-Known Member

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            Yes, the assembly is custom built so you specify everything. Width, axle offset, bolt pattern, location and angle of pads, pinion offset, etc. Plus you have to pick all the parts. I upgraded most of the parts since I'm running a 512 inch low deck and didn't want to break anything.
             
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            • Mopar Hunter

              Mopar Hunter Well-Known Member

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              Smart, good time to take advantage of Strange Engineering’s 10% off and free freight through Doctor Diff.

              I saved a bunch of money by switching to Doctor Diff. too.
               
            • andyf

              andyf Well-Known Member

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              Yep, I knew I was going to buy a new rear end this year so I waited until the annual sale started and then pulled the trigger.
               
            • rolling_Thunder

              rolling_Thunder Well-Known Member

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              Not to be arrogant or an entitled pr!ck - but what made you go with the 9" over an 8 3/4? I know the 9" is claimed to be (and probably is) stronger and there is WAY more aftermarket support for it - but I personally don't see the draw beyond that. Do I need a rear that will take 1000lb-ft if I only make 600?

              Just curious why you went that direction vs the (arguably) easier 8 3/4 route
               
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              • beanhead

                beanhead Well-Known Member

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                Nice Andy...is it going in the Duster? Or your Coronet.
                 
              • andyf

                andyf Well-Known Member

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                The 9 inch will replace the S60 that is currently under the Duster. I got a new S60 with 3.23 gears from Doctor Diff last summer for the Coronet.
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                • andyf

                  andyf Well-Known Member

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                  An 8 3/4 wouldn't be a good choice for this car. The 9 inch was really the only choice that would work. The car currently has a S60 under it but I needed to make some changes and a 9 inch was the only thing that checked all the boxes.

                  I'll sell the existing S60 once I have the 9 inch installed and working. It is a nice setup with 4.10 gears and a Detroit Locker but I needed something different for the new setup.
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                  • andyf

                    andyf Well-Known Member

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                    I got the Baer brake kit installed and then weighed the full assembly. It is 212 lbs dry so it will end up right at 220 lbs once I add a gallon of gear oil. I need to weigh the S60 after I pull it out from under the car before I'll know the difference. I'm assuming that the 9 inch is lighter but I don't know by how much. I will need a new driveshaft though. The 9 inch is about 3 inches shorter than the S60.
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                    • 33 IMP

                      33 IMP FBBO Gold Member FBBO Gold Member

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                      I'm sure we are all curious about the weight difference. ( i will bet it's a lot less than most think. I bet it's not more than twenty pounds.)
                      Edit: also curious how well the true track holds up.
                       
                      Last edited: Nov 26, 2020
                    • F4R/T

                      F4R/T Well-Known Member

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                      The difference in drag or lost hp/ torque is what I’d be interested in. The 9” has a pocket bearing and smaller pinion diameter and bearings if I’m not mistaken. Hot Rod or one of those mags did a big study on them and the 8&3/4 is the disrespected slugger and the Dana is the knock out punch.. Best of luck keep us posted .
                       
                    • andyf

                      andyf Well-Known Member

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                      No difference in drag when rotating by hand. The 9 inch takes about 35 inch-lbs to rotate with the brakes installed. Roughly the same amount of rotating torque that the S60 takes. Maybe it is different when loaded but I'm not set up to measure that. I'm not really worried, I've worked on a lot of fast cars with this same basic 9 inch setup.
                       
                    • watermelon

                      watermelon FBBO Gold Member FBBO Gold Member

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                      looks awesome...yeah....i wouldnt know what else to spec beyond “Need it to fit a 1966 Dodge Coronet 500”


                      watermelon
                       
                    • 5.7 hemi

                      5.7 hemi FBBO Gold Member FBBO Gold Member

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                      A Dana 60 does require LESS hp to turn.
                       
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