3:73 or 4:10

[AH64ID]

Well, sorta. You get maximum torque multiplication at stall (i. e. , output speed of the torque converter = 0 RPM), but there's reduced torque multiplication available any time the converter is unlocked.



Rusty

Thanks... Never been much of an auto guy.

 

[RustyJC]

Buried in those numbers is one of the reasons that current automatic-equipped Rams often have higher trailer tow ratings than manuals (by the way, I'm NOT anti-manual - my previous truck was a 2002 ETH/DEE 3500 dually). Maximum launch force (in pounds) can be computed as follows:



Engine torque x torque converter multiplication ratio x 1st gear ratio x rear axle ratio / rolling radius of rear tire (in feet). For a 30 inch tire and a new HO Cummins with the MaxTow package, this would be:



800 lb-ft x 2. 25 torque converter multiplication ratio x 3. 231 1st gear ratio x 4. 10 rear axle ratio / (15 inch radius / 12 inches in 1 foot) =



800 X 2. 25 X 3. 231 X 4. 10 / 1. 25 = 18610. 56 lbs



If the same combo were available with the NV5600 instead of the 68RFE, launch force would be:



800 x 5. 63 x 4. 10 / 1. 25 = 14773. 12 lbs



Not considered in the above is the "softer" power delivery characteristic of the torque converter-equipped 68RFE powertrain that minimizes peak torque shocks on the truck's driveline compared to a ham-footed operator who might side-step the clutch at launch - something the engineers must consider as a possibility.





Rusty

 

[AH64ID]

But with those calculations you are forgetting tq management, as 800 ft/lbs isn't available until 4th gear in the 68RFE, and the manual is de-rated until a certain speed, I think its 35 mph.

 

[RustyJC]

But with those calculations you are forgetting tq management, as 800 ft/lbs isn't available until 4th gear in the 68RFE, and the manual is de-rated until a certain speed, I think its 35 mph.

Good point - you're right; I didn't take torque management into consideration, but the comparison in overall torque multiplication between the two powertrain configurations still holds.



Rusty

 

[AH64ID]

Yes it does, gearing aside it's too bad Dodge won't put in a clutch/trans that will hold 800 ft/lbs and have 2 OD's.

 

[AH64ID]

I spent a few minutes looking at the tow ratings...

3. 42's, the manual is rated at 2K lbs higher GCWR which translates to 1950 lbs more towing, based on curb weight differences.

3. 73's, the auto is rated at the same GCWR, but has 50lbs more towing capacity based on curb weight.

The only auto that has a higher GCWR is the Max Tow option on a DRW, the SRW auto has the same GCWR.

 

[RustyJC]

On my truck (see signature):



G56 with 3. 42 - 19,000 GCWR

G56 with 3. 73 - 21,000 GCWR

68RFE with 3. 42 - 17,000 GCWR

68RFE with 3. 73 - 21,000 GCWR

68RFE with 4. 10 - 26,000 GCWR



Of course, with my 2002, to get the maximum GCWR available that year, I had to order the 3500 dually with Cummins HO, NV5600 and 4. 10 gears to get a 21,500 GCWR. I guess that was my point - one couldn't get to the 26,000 GCWR with a manual when I ordered my current truck. So, the best GCWR in 2002 was with the manual, whereas the best GCWR in 2011 was with the automatic.



Rusty

 

[Phil Stuart]

Excellent information folks.



I've decided to go with the H/O , 68RFE and 4. 10 gears along with the max tow package (comes with 4. 10).



Phil

 

[AH64ID]

Of course, with my 2002, to get the maximum GCWR available that year, I had to order the 3500 dually with Cummins HO, NV5600 and 4. 10 gears to get a 21,500 GCWR. I guess that was my point - one couldn't get to the 26,000 GCWR with a manual when I ordered my current truck. So, the best GCWR in 2002 was with the manual, whereas the best GCWR in 2011 was with the automatic.



Rusty

Gotcha, I really don't understand why they don't offer 4. 10's with the G56? The 3500 C&C has a 4. 10's and a manual and a 26K GWR for both manual and auto, with lower power so it's not a power thing... I think too many people complained about highway rpms with 4. 10's and a manual and (just like the oil psi on the dash) they deleted the option to eliminate complaints.

 

[SearsK]

4:10's, got'em in my 2011 dually

 

[JJPage]

I guess everyone disagreed with me, For me it's still 3. 73, maybe the mini-max with low setting and turbo tune is why I have no preference to the 4. 10. I had 4. 10 in my 03 and could never cruise anything over 70 as fuel milage would plumit.

I would not disagree with you on general principle, I would personally have to tow with a 6 speed auto, before I could make the choice between the two ratio's.



75% of the folks on here(TDR) also believe 4:10's are the best choice for towing with a 48re. I strongly disagree, but that is based on my towing experience with my truck. I tow mostly on the Interstate + - 70mph, 4:10's would be miserably slow, or mileage would totally suck because I would be at 2k rpms+ to maintain that speed. Before someone chimes in and states the max torque is between 2000k/2200k rpm, and that's where you should be operating, I concede that may be the rpm where highest torque is achieved, I disagree it is the sweet spot for towing.



Go tow across I-90 in E Montana/Dakota(I-40 TX) with 4:10's, gonna be a long day! Now take a trip not towing w/4:10's.....



Why do you believe there are so few 4:10 trucks available if they are the ultimate towing configuration?



Before someone gets their panties in a bunch, these are my opinions about a 48re auto w/4:10's vs 3:73's, you will not change my mind. As stated first, I would have to tow with a 6sp auto before I could make a decision about them. My point is, just because most people believe 4:10's are the way to go... have they towed with a 6sp auto and 3:73's ? I would not pass up an available truck w/3:73's , just because...

 

[AH64ID]

The 48RE's tall OD made it a lousy combo with 4. 10's for towing. . You still couldn't hold 60-65 in OD, but were SCREAMING in 3rd. With double OD's on the 68RFE you can have gears and low cruise rpms.

 

[Turboman]

If you also factor in taller tires like alot of us do you get your rpms even lower. My current rig runs lower rpm (1825 at 70) than my '02 ETH/DEE did (1925 at 70) with same tires. I love the 4. 10s, but have not towed with 3. 73s either.

 

[RustyJC]

With factory tires and 4. 10 gears:



2002 3500 dually, ETH/DEE, @ 70 MPH - 2350 RPM



2011 3500 dually, 6. 7L/68RFE @ 70 MPH - 1880 RPM



Check the GCWRs to see how much more tow capacity the 4. 10s get you with the new trucks, in the Dodge engineers' analysis. Not much comparison!! I could have bought any number of 3. 73 trucks off of dealers' lots, but for my purposes, I ordered the truck in my signature with the 4. 10s.





Rusty

 

[Cummins12V98]

What are the rpm's at 60 with all 3 difs with the 6 sp auto?



Thanks

 

[JJPage]

The 48RE's tall OD made it a lousy combo with 4. 10's for towing. . You still couldn't hold 60-65 in OD, but were SCREAMING in 3rd.

I can hold 60mph+ in OD w/3:73's(35" Toyo's towing), no problem at all, cruise all day. So your statement about not holding 60-65 w/4:10's/Auto, is not accurate... I do have a built 48re.

I love the 4. 10s, but have not towed with 3. 73s either.

My point exactly, so many folks believe 3:73's are not "towing friendly", but have also not experienced the combo.

With factory tires and 4. 10 gears:



2002 3500 dually, ETH/DEE, @ 70 MPH - 2350 RPM



2011 3500 dually, 6. 7L/68RFE @ 70 MPH - 1880 RPM



Rusty

I could live w/1880@70mph, this is good 1st hand info. I would like to see real world w/3:73's.



I have not driven a 6. 7, I almost never run my 5. 9 above 2k for any length of time, and would not want to. Dad always wanted us to run his 220/250/335/350's @ 2250rpm, no exceptions. later when the 400's+ came out, Cummins wanted everything between 1650/2000, this was really against the grain, so to speak.



I know where my engine produces the most power, it is above 2k, I also know where it gets the best mileage, below 2k. It has enough power(stock program) below 2k to tow anything I want.



Jess

 

[RustyJC]

What are the rpm's at 60 with all 3 difs with the 6 sp auto?



Thanks

3. 42 - 1344 RPM @ 60 MPH



3. 73 - 1466 RPM @ 60 MPH



4. 10 - 1612 RPM @ 60 MPH





Rusty

 

[AH64ID]

I can hold 60mph+ in OD w/3:73's(35" Toyo's towing), no problem at all, cruise all day. So your statement about not holding 60-65 w/4:10's/Auto, is not accurate... I do have a built 48re.

Jess

That's 1550-1700 rpms, so at what weight (and your hardly stock)? With 4. 10's its 1700-1850 rpms (35's) and 1850-2000 (stock tires) and most motor's wont hold those rpms on any decent hill. 3rd with stock tires at 60-65 is 2700-2925, too fast for most.

Unless heavily modified on the trans/power department I stand by my comment. The 48RE and 4. 10's is not a great towing combo for highway/freeway speeds.

 

[JJPage]

That's 1550-1700 rpms, so at what weight (and your hardly stock)? With 4. 10's its 1700-1850 rpms (35's) and 1850-2000 (stock tires) and most motor's wont hold those rpms on any decent hill. 3rd with stock tires at 60-65 is 2700-2925, too fast for most.



Unless heavily modified on the trans/power department I stand by my comment. The 48RE and 4. 10's is not a great towing combo for highway/freeway speeds.

Your right, I am not stock, however I do tow with either a stock program or Smarty on sw1 max. I believe my Flux 1. 2's are around 60/65hp, and with the Arson III, I am probably 100hp over stock while towing and am certain that does make a big difference.



I also agree the 48re/4:10 combo would not be good at Interstate speeds for my driving style, but the 48re/3:73 is. .



I would really like to drive/tow with a new 6. 7 with a 6sp auto, and try out the different ratio's. Unfortunately, I know of no place a person can do that without a purchase.

 

[AH64ID]

I run about 100hp over stock all the time, towing or not, and yeah it makes a nice difference!

I haven't driven a new 6 speed yet either, but the numbers sure do make me think twice about one. . At least I'm not thinking about a new truck, the 05 does everything I need and more.