19-up gears

[BadRam3500]

Whats up fellas ?!
I’ve been calling Randy’s worldwide religiously every 3 months ever since I bought my 2021 3500 h.o. Back in 2021.
They still don’t have any gears for the trucks with the aam 12 inch axle . Does anyone know any other manufacturer that might have some ?
My truck needs help spinning the 42’s .

 

[RPS1030]

Dixie 4 Wheel Drive swapped a 4th Gen Axle into a project truck to re-gear it.

 

[BadRam3500]

That’s pretty much what I was thinking I was going to have to do .
You you think it’ll be an easy swap ?

 

[AH64ID]

Whats up fellas ?!
I’ve been calling Randy’s worldwide religiously every 3 months ever since I bought my 2021 3500 h.o. Back in 2021.
They still don’t have any gears for the trucks with the aam 12 inch axle . Does anyone know any other manufacturer that might have some ?
My truck needs help spinning the 42’s .

Drop to an 11.5” R&P if you really want to regear it. The SO trucks still use the 11.5” R&P in the same housing the 12.0” is in. I can’t see why you would need to do an axle swap.

 

[MDethloff]

Randy's now has gears and a carrier for the 12.0.

Based on my measurements it looks like the 4500/5500 gears are actually a direct fit into the 3500 axle, if you use a 4500/5500 carrier made for the higher 4.44/4.88 ratios. You would need to swap the spider gears in your current carrier into the new carrier, because the C&C's and dually 3500 have a different spline count than the SRW 3500 axle.

Drop to an 11.5” R&P if you really want to regear it. The SO trucks still use the 11.5” R&P in the same housing the 12.0” is in. I can’t see why you would need to do an axle swap.

This is unfortunately not the case, once Ram switched from the 11.8 to the 12.0 it all changed internally. The pinion/gear placement, bearing diameters and widths, etc. are all different. You cannot put an 11.5 gearset into a 12.0 axle.

 

[AH64ID]

You cannot put an 11.5 gearset into a 12.0 axle.

Yet Ram does it in all 19-24 SO 6.7’s and 6.4 Hemi’s.

All 19+ trucks have the 12.0” housing, but only HO’s get the 12” R&P.

 

[MDethloff]

Yet Ram does it in all 19-24 SO 6.7’s and 6.4 Hemi’s.

All 19+ trucks have the 12.0” housing, but only HO’s get the 12” R&P.

They do look almost identical at a glance, it's difficult to tell them apart without getting picky, but we have compared all of the factory CAD data and I have had a 2019 2500 Cummins and a 2024 3500 HO side by side next to each other - they LOOK very similar, but at close inspection they are different axles. Almost every part of the 12.0 is different than the 11.5" axle. Center casting, tubes, axle shafts, carrier, bearings, R&P are all different. There is a definite visual similarity between them, however they are different throughout their construction.

The 2019-24 SO/hemi trucks do have an updated 11.5 housing but it isn't the same as the 12.0.

If you're absolutely 100% positive that the gears interchange and you know people that have done it on a 2019+ truck I'd love to take another look, but so far we've sliced it every way we think we can and they're totally different axles. I'd love to get a locker in the 12.0.

 

[AH64ID]

They do look almost identical at a glance, it's difficult to tell them apart without getting picky, but we have compared all of the factory CAD data and I have had a 2019 2500 Cummins and a 2024 3500 HO side by side next to each other - they LOOK very similar, but at close inspection they are different axles. Almost every part of the 12.0 is different than the 11.5" axle. Center casting, tubes, axle shafts, carrier, bearings, R&P are all different. There is a definite visual similarity between them, however they are different throughout their construction.

The 2019-24 SO/hemi trucks do have an updated 11.5 housing but it isn't the same as the 12.0.

If you're absolutely 100% positive that the gears interchange and you know people that have done it on a 2019+ truck I'd love to take another look, but so far we've sliced it every way we think we can and they're totally different axles. I'd love to get a locker in the 12.0.

Hmm, that doesn’t make any sense with what I’ve seen.

Why have 3 axle variants? The PW still uses the 11.5/11.8 while the rest of the HD fleet has the 11.5/12.0.

 

[MDethloff]

Hmm, that doesn’t make any sense with what I’ve seen.

Why have 3 axle variants? The PW still uses the 11.5/11.8 while the rest of the HD fleet has the 11.5/12.0.

We primarily worked with the Power Wagons until a few years ago. I believe that the old 11.5 has been maintained under the Power Wagons so that the locker machining/wiring/install did not need to be redone on the new axle. The new 11.5 was most likely done for weight reduction or some other purpose. The new 12.0 may be out of a concern that the 11.5 did not meet their minimums for the HO torque/power.

It is interesting that there are three concurrent axles, but that is what we're seeing. We had a 21' Power Wagon, and 19' 2500 Cummins, and a 24' 3500 HO Cummins next to each other in the shop, and there was a different axle under each one.

 

[AH64ID]

We primarily worked with the Power Wagons until a few years ago. I believe that the old 11.5 has been maintained under the Power Wagons so that the locker machining/wiring/install did not need to be redone on the new axle. The new 11.5 was most likely done for weight reduction or some other purpose. The new 12.0 may be out of a concern that the 11.5 did not meet their minimums for the HO torque/power.

It is interesting that there are three concurrent axles, but that is what we're seeing. We had a 21' Power Wagon, and 19' 2500 Cummins, and a 24' 3500 HO Cummins next to each other in the shop, and there was a different axle under each one.

I agree on the locker for the PW. My understanding is that the new 11.5” was done to fit the new 12.0” housing to reduce cost.

What did you find different on the tubes between the new 11.5” and 12.0”?

I still think there is something being missed with the 11.5/12.0, GM is doing the same thing with one housing and different guts from what I’ve read…. But we also know that everything we read is accurate.