Cummins goes to 1075 lb-ft

[DeansRedRam]

Ah, yes my mistake. Yeah the route they take when they top the tank off two times.

 

[Ltngdrvr]

Towing our home on wheels West 20 TX right now. It’s 41 out and trans is running 163. If it were 100 the trans on a long 6% grade may get to 170. So that’s just one reason.

Only 34k combined

68RFE in mine never runs hot, no matter what I'm towing, think 177 is the hottest it's ever been, and that was before the swap to the mishimoto radiator, can't recall it going above 170 since.

Now, of course, don't ever get up to 34K towing with my 2500, more like 22K-24K max.

 

[AH64ID]

Bigger axles yes but I can't find anything about bigger brakes. I believe because of the larger axles/bearings the wheels on ALL duallies, HO or not, the wheels are different (8 x 200?) because Ram couldn't see complicating things with two different bolt patterns for duallies.

Ram is still updating their materials...HO HP rating will be 420.

It's not a bigger axle, it's the same 12" AAM axle. The difference is the ring gear bolts and carrier to accept the additional bolts.

The AAM axles have always had the same vertical load rating for SRW or DRW.

 

[Cummins12V98]

On the MPG, I was referring to the loaded MPG loop they do, which is separate from the Ike, and they hand calculate the mileage. I agree looking at the Lie-O-Meter for a foot to the floor run is pretty worthless.

You mean the click wait then click method? NOT hand calc in my book. I fill to the top every tank, that’s hand calculated.

 

[Cummins12V98]

68RFE in mine never runs hot, no matter what I'm towing, think 177 is the hottest it's ever been, and that was before the swap to the mishimoto radiator, can't recall it going above 170 since.

Now, of course, don't ever get up to 34K towing with my 2500, more like 22K-24K max.

My 11 HO DRW 68 towing 29k combined always ran cool. But AISIN is cooler.

 

[DeansRedRam]

It's not a bigger axle, it's the same 12" AAM axle. The difference is the ring gear bolts and carrier to accept the additional bolts.

The AAM axles have always had the same vertical load rating for SRW or DRW.

It's to my understanding you can only get the 12" rear diff on a Dually 3500 Max tow, read that on the Ram website and you'll notice it when you build a truck, but all 2500/3500SRW are 11.5.

2018 and lower (not sure how old back), with the Dually/H.O./Maxtow you got the 11.8 w/ the finned rear diff cover.

 

[TFucili]

You mean the click wait then click method? NOT hand calc in my book. I fill to the top every tank, that’s hand calculated.

Whatever the method, the Ford got better MPG when dividing miles by gallons. Ford's new combo gained MPG, whether it's attributed to tuning, or the 10 speed. The CGI Cummins are thirstier on fuel and DEF than -->'18s were.

 

[AH64ID]

It's to my understanding you can only get the 12" rear diff on a Dually 3500 Max tow, read that on the Ram website and you'll notice it when you build a truck, but all 2500/3500SRW are 11.5.

2018 and lower (not sure how old back), with the Dually/H.O./Maxtow you got the 11.8 w/ the finned rear diff cover.

Yes the ring gears are different, should have stated the same 12” axle housing. All 19+ trucks, GM and Ram, use the new AAM 12” housing, as far as I know.

Here is a build sheet for a 3500 SRW with the 12” axle listed on it.

https://www.jeep.com/webselfservice/BuildSheetServlet?vin=3C63R3KLXLG221740

Just as with a 11.8” vs a 11.5”, only a ring gear difference to support a higher GCWR and larger pinion gear on 4.10’s. The 11.8” gear will bolt right up to a 11.5” carrier thou, unlike the 12” gears to a 11.5” carrier.


Looks like 2500’s still use the 11.5” thou. I did not know that.

https://www.jeep.com/webselfservice/BuildSheetServlet?vin=3C6UR5CL7LG194074

Also didn’t know that the 3500 SO has an 11.5”. I guess I’ve only been following HO’s.

https://www.jeep.com/webselfservice/BuildSheetServlet?vin=3C63R3JL7LG220899

I need to look at pumpkins again, since I only recall seeing the 12” housing on any 19+ truck.

 

[AH64ID]

Ok, so I had to run an errand and the Ram dealer was a 1/2 mile down the road so I stuck my head up some skirts.

All 2500/3500 trucks have the same housing. Obvious width difference between SRW/DRW and suspension hard points. All are the same pumpkin and axle tube diameter. This is what I had noticed previously, but measured and verified today.

What I learned today is that only the HO and/or DRW trucks get the axle stuffed with the 12” R&P vs the 11.5” R&P.

So, just like the 11.5 vs 11.8, the axle is the same the R&P is different.

2500 Gas

2500 Cummins

3500 SRW SO

3500 SRW HO

3500 DRW

 

[DeansRedRam]

Interesting.. I'm not doubting you, but did you actually take measurements of the axle?

Maybe they do this to order a bunch of the same axle housings and save cost that way by just changing the R&P.

I'm surprised to not see a cooling finned diff cover on the 3500 DRW HO.

 

[Wiredawg]

So, the Max Tow trucks no longer have the aluminum finned cooler pumpkin cover. Haven't been looking at trucks since buying my wifes 1500 a couple years back.

Thanks, Ron

 

[AH64ID]

Interesting.. I'm not doubting you, but did you actually take measurements of the axle?

As stated, measured.

Maybe they do this to order a bunch of the same axle housings and save cost that way by just changing the R&P.

Most likely. Even the older 11.5” housing has more than enough load capacity for the current DRW. The difference is the ability to support torque and GCWR.

I'm surprised to not see a cooling finned diff cover on the 3500 DRW HO.

Honestly I’m not. I don’t think it was ever actually needed.

Not Apple-apples by my MH cover really cut fuel economy in the winter until it was up to operating temp, which was not fast when it was cold.

 

[AH64ID]

So, the Max Tow trucks no longer have the aluminum finned cooler pumpkin cover. Haven't been looking at trucks since buying my wifes 1500 a couple years back.

Thanks, Ron

They don’t. I can’t recall if they dropped in 19 or if it was before that.

 

[Ltngdrvr]

So, the Max Tow trucks no longer have the aluminum finned cooler pumpkin cover. Haven't been looking at trucks since buying my wifes 1500 a couple years back.

Thanks, Ron

They don’t. I can’t recall if they dropped in 19 or if it was before that.

Heck, they probably save 10 bucks a truck by not including the aluminum cover!

 

[mpaulson]

Somewhere in the last 10 years there was a post where someone had cut the axle tubes and the 3500 DRW tubes were 1/2" wall thickness and the SRW trucks tubes were 3/8" or a little lighter. Otherwise they were the same, looked the same and had the same 4" O.D. on the tube. I would bet this is still the case.

 

[AH64ID]

Somewhere in the last 10 years there was a post where someone had cut the axle tubes and the 3500 DRW tubes were 1/2" wall thickness and the SRW trucks tubes were 3/8" or a little lighter. Otherwise they were the same, looked the same and had the same 4" O.D. on the tube. I would bet this is still the case.

When I called AAM and asked about this they said that they were identical.

Both SRW and DRW versions used the same tubes, per application. He went onto talk about the differences in the GM and Dodge/Ram axles. Different size tubes, but same vertical load rating. AAM specs the tube thickness based on the requested tube diameter. He did go onto mention that Dodge/Ram spec better quality bearings than GM. He called them 3x life vs 2x life.

I’ve never cut them open, just going off what AAM told me.

There were also upgrades to the axle in the 06 timeframe, again around 13, and now the new 12 housing for 19.

 

[gsbrockman]

Not Apple-apples by my MH cover really cut fuel economy in the winter until it was up to operating temp, which was not fast when it was cold.

Do you attribute that to the efficiency of the aluminum cover, the additional fluid capacity, or a combination of both?

 

[AH64ID]

Do you attribute that to the efficiency of the aluminum cover, the additional fluid capacity, or a combination of both?

Both. Better cooling and more fluid.

If I were to do it over I would do the OEM cover or have stayed stock. My 18 is stock steel.

 

[DeansRedRam]

I plan to do the Banks Cover, have heard a lot of good things, and I like that it retains stock fluid capacity.

 

[AH64ID]

I plan to do the Banks Cover, have heard a lot of good things, and I like that it retains stock fluid capacity.

I saw one in the parking lot the other day and personally wouldn’t touch it, even it didn’t say banks. It hangs down to catch air, which to me is a huge hazard for road debris on and off the pavement.

I also don’t want that much cooling when running empty, as it will cost more fuel.

Then there is the banks aspect, but to each their own. I don’t think it’s a great design and it’s astronomically expensive for what it does.