HMMWV Differential Assy Question

[StormChaser]

I've searched like crazy to find the answer to this, but no luck. I have found that both the front and rear differentials have the same NSN and part numbers, thus are interchangeable. I have a good working understanding of differentials, but I am having trouble understanding how this is possible. If they are the same differential, then spinning one around for use in the front would mean that internally, it would have to be spinning everything in the opposite direction as the rear in order for all the wheels to turn the same direction.

Given the same part numbers for each unit, it stands to reason that they are internally the same as well (meaning, same gears, or, no reverse-cut gears for the front). This would mean that the front pinion would have to be applying it's pressure to the "coast" side of the ring gear, which is universally seen as a no-no for gear longevity.

So, what am I missing?

 

[gringeltaube]

So, what am I missing?

.... probably the fact that this being a MV, the designers choose parts interchangeability before parts longevity?

And BTW, look at the full-time FWD M880-series: their #44 front diff. also spins "backwards" and still seems to last forever.

 

[papakb]

These are Torsen differentials and their internal gearing is different from what your used to. Torsen is the differential type and not the manufacturer.

 

[86humv]

They are AMC 20 diff's

 

[Mogman]

Seems to me every 4WD vehicle I have ever seen uses the same gear set etc. in both differentials, if you look at the pinion flange on the front diff it is turning counter clockwise, the rear is turning clockwise, so the front diff is just running in "reverse" which makes all the wheels turn the same direction..

EDIT, of course I am speaking of 4WD vehicles that are running the same type of differential front and rear, many have a different type front/rear differential, theory is the same but technically they do not run the same gear set.

 

[AOR]

One example of a production vehicle off the top of my head is the 2003-2006 Jeep Wrangler Rubicon models have Dana 44 axles both front and rear and the ring and pinion gear sets are the same part number front and back

 

[Vapor Trail]

I have both my differentials laying on the ground ready to put back on vehicle but I don't know which is which. 2004 M1123 A2. When I took them off I thought they were interchangeable but I marked them anyway and now that they're painted they're not marked anymore. Can they be put in either place and if not how do you tell which is which?

 

[Coug]

a very quick look in the parts manual showed me that the front and rear differential are the exact same part number for all A2 trucks.

 

[Retiredwarhorses]

I have both my differentials laying on the ground ready to put back on vehicle but I don't know which is which. 2004 M1123 A2. When I took them off I thought they were interchangeable but I marked them anyway and now that they're painted they're not marked anymore. Can they be put in either place and if not how do you tell which is which?

The yoke is the only difference….front and rear are different size, rear being larger.