Got the new 9 inch from Doctor Diff

[andyf]

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.

 

[Bee1971]

That’s a pretty rear end

 

[yella71]

you own a ford?

 

[gkent]

This is a Chrysler forum.

 

[yella71]

This is a Chrysler forum.

Yes. It is

 

[gkent]

not small block chevy ... LS !!!

 

[5wndwcpe]

Andy, do you get to specify the pinion angle ?

 

[andyf]

Andy, do you get to specify the pinion angle ?

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.

 

[Mopar Hunter]

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]

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.

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]

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

 

[beanhead]

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

 

[andyf]

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

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.

 

[andyf]

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

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.

 

[andyf]

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.

 

[33 IMP]

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.

 

[F4R/T]

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]

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 .

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]

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


watermelon

 

[5.7 hemi]

A Dana 60 does require LESS hp to turn.