Differential Case Sizes?

[summerinmaine]

As part of my investigation on re-gearing my D44 & D30, I ran across this site: http://www.drivetrain.com/dana44.html and it contains listings for different size cases for each of the D44 and the D30 (3.73 appears to be the break point).

 

I've never heard or read of any different size cases for a particular model diff, so I'm a bit confused. Is there such a thing? If so, how do you re-gear a 3.07 into a 4.10? I thought it was a standard size for the ring gear in each particular model (8.5" for the D44 IIRC), which shouldn't involve a different size case. They have two different prices, depending on whether the case is empty or loaded. Anyone know what they're talking about?

[Eagle]

They are using "case" to refer to the "carrier." For most differentials (the Chrysler 8-1/4" is an exception) there are two carriers, because as the number of teeth on the ring gear changes they get to a point where they need to change the thickness of the ring gear. That requires a carrier with a flange of a correspondingly different thickness.

 

It's referred to as the "carrier break," and the ratio at which it occurs is different for various axles. (In other words, the break isn't between the same two ratios for the D30, the D35, the D44, and the D60).

 

The answer is, if you are changing to a ratio on the other side of the carrier break from your current ratio, you buy a new carrier (or, depending on which way you're going, a ring gear spacer). That's why I was suggesting to you that you should really look into a limited slip. You have to buy a carrier anyway, so why not buy a carrier that improves your off-road functionality?

 

BTW - The carrier break for the D30 is between 3.54 and 3.73. For the D44 the break is from 3.73 to 3.92. This means you will need a new carrier for the front, but for the rear you can use the original carrier if you're changing to 3.73s, and you'll need a new carrier if you're changing to 4.10s.

[BLHTAZ]

When you say "case", it's the carrier that you are talking about. The carrier is the part that the ring gear mounts on and if you are going from 3.07 to 4.10, it will require a different carrier as the 3.73 & up carrier is different.

 

The empty vs. loaded simply means that it has or doesn't have spider gears in it. Get it empty if you are going to go with a limited slip or other type of in carrier style traction device.

[BLHTAZ]

:D Eagle & I are on the keys at the same time... ;) :cheers:

[summerinmaine]

They are using "case" to refer to the "carrier." For most differentials (the Chrysler 8-1/4" is an exception) there are two carriers, because as the number of teeth on the ring gear changes they get to a point where they need to change the thickness of the ring gear. That requires a carrier with a flange of a correspondingly different thickness.

 

I thought that might be the "case" but was confused as they also have price listings for carriers as well as cases.

[redneck23ms]

d30 carrier break is between 3.55 and 3.73

[Eagle]

d30 carrier break is between 3.55 and 3.73

Right you are. My bad -- I read the wrong line from my spreadsheet.

 

Good catch. Thanks.

[BLHTAZ]

A differential "case" ( to me ) would mean the complete axle housing (exterior) that the carrier is mounted in.

[CWLONGSHOT]

A differential "case" ( to me ) would mean the complete axle housing (exterior) that the carrier is mounted in.

 

Ditto

[summerinmaine]

A differential "case" ( to me ) would mean the complete axle housing (exterior) that the carrier is mounted in.

 

Same here. I would interpret "case" as "housing" not "carrier."

 

That's why I got confused.

[Eagle]

A differential "case" ( to me ) would mean the complete axle housing (exterior) that the carrier is mounted in.

 

Same here. I would interpret "case" as "housing" not "carrier."

 

That's why I got confused.

I think most of us here are in agreement. They used incorrect terminology. I have never heard a carrier referred to as anything other than a carrier ... until today.