04.5 with 4.10's <vs> 07.5 with 3.73's towing 15,500lbs

[Top Gun]

Hello gents :



I'm thinking about moving from an 04. 5 to an 07. 5 and wanted to know if I will "feel" a difference towing 15,500 pounds. Both are automatics ( A4 vs A6 ) and the 04. 5 has 4. 10's and 07. 5 has 3. 73's.



Will the 2 extra gears in the Aisen A6 "make up" any difference for having higher gears ( lower numerically ) in this instance ? My towing is recreational and only a few times a month with it being approximately 100 miles round trip each time.



Thanks in advance !

 

[Wingate]

I thought the Aisin was only available in the 4500-5500 C&C trucks??? I thought the C&C trucks came with 4:33 and 4:88 gearing???

 

[Road Dog]

The pickups come with a Chrysler 68RFE and the C&C comes with an Aisin.

 

[RVTRKN]

Hello gents :



I'm thinking about moving from an 04. 5 to an 07. 5 and wanted to know if I will "feel" a difference towing 15,500 pounds. Both are automatics ( A4 vs A6 ) and the 04. 5 has 4. 10's and 07. 5 has 3. 73's.



Will the 2 extra gears in the Aisen A6 "make up" any difference for having higher gears ( lower numerically ) in this instance ? My towing is recreational and only a few times a month with it being approximately 100 miles round trip each time.



Thanks in advance !

This question is asked alot, and there are two basic answer's. If towing 50% of its life or less than the 3:73 is best, but if more than 50% 4:10 is the better way to go. The 3:73 was a good compromise from 3:54, which is way to low for a heavy GCVW. I ordered my truck with the 3:73, but mine has the G56 Manual, and except for the California towing at 55 MPH, I save lots of money in city driving. The California issue when towing has a disadvantage due to 55 MPH and slight grades where it causes you to bog your engine and you have to down shift to 5th and cause you to run higher RPM's. If running at 65 MPH, the slight grades at a heavy GCVW are within the sweat spot for your CTD. Normally I always downshift for any grade, but these grades are so slight, I shift back into 6th and you end up hunting for the right gear, I dread the 55 MPH towing law. With the 4:10 and heavy towing you save fuel because it easier on the engine, but lose that in the city/Hwy empty, so if your towing more than 50% of its life you save on fuel.

 

[AH64ID]

The 4. 10's offer a 10% mechanical advantage over 3. 73's. The 6. 7 makes about 6. 5% more torque than the 5. 9 so the difference will not be huge. If you do deletes I bet you can't tell most the time.

 

[p-Bar]

since we are talking gears would like some input . I tow a fiver a few times a year my truck is used for my work I carry 500lbs tools in the back . After a fill up my scan gauge II says my average mph is about 35 for the tank with this info would it be advisable to go fro 3:73 to 4:11 ?? looking for better mileage Thanks

 

[AH64ID]

I doubt you would see any difference, certainly not enough to justify the cost.

 

[HBarlow]

All automatic transmission cab and chassis trucks, Ram 3500, 4500, and 5500 use the Aisin six speed automatic. Differential gearing varies with the platform. 3. 73 and 4. 10 are offered in the 3500, 4. 10 and 4. 44 in the 4500, and 4. 44 and 4. 88 in the 5500.

Pickups never offer Aisin automatics, only the MOPAR 68RE.

3. 73 differential gears are okay with the G-56 manual but are never suitable for towing with six speed automatics. The six speed automatics have overdrive ratios in fifth and sixth gears. 3. 73 gears will force the owner to tow at 80 mph or downshift to a lower gear to allow the engine to operate within the torque band.

The six speed automatic trucks with 4. 10 gears will run about 1800-1900 rpm at 70 mph in top gear.

The fuel consumption rate differential between 4. 10 and 3. 73 or even 3. 42 gears is barely noticeable with the Cummins engine. Theoretically I'm sure there is some difference. In actual driving, not much.

 

[CUMMINZ]

Comparing the two trucks the real difference is between the four and six speeds not the rear gearing. The six gears will far out perform the four speeds.

 

[AH64ID]

If we assume that 2200 is the "sweet spot" here is what you will see.

48RE w/ 4. 10's
3rd gear 49 mph
4th gear 71 mph

68RFE w/ 3. 73's
4th gear 54 mph
5th gear 66 mph
6th gear 85 mph

68RFE w/ 4. 10's
4th gear 49 mph
5th gear 60 mph
6th gear 78 mph

Below 45 mph I am not sure the difference is enough to compare, 2nd on the 48RE is nearly the same as 3rd on the 68RFE and there are 2 lower gears on the 68RFE to get the load moving, with 1st being 33% lower on the 68RFE so 4. 10 vs 3. 73 is really a 45 mph and up comparison.

 

[Hoefler]

If we assume that 2200 is the "sweet spot" here is what you will see.



48RE w/ 4. 10's

3rd gear 49 mph

4th gear 71 mph



68RFE w/ 3. 73's

4th gear 54 mph

5th gear 66 mph

6th gear 85 mph



68RFE w/ 4. 10's

4th gear 49 mph

5th gear 60 mph

6th gear 78 mph



Below 45 mph I am not sure the difference is enough to compare, 2nd on the 48RE is nearly the same as 3rd on the 68RFE and there are 2 lower gears on the 68RFE to get the load moving, with 1st being 33% lower on the 68RFE so 4. 10 vs 3. 73 is really a 45 mph and up comparison.

These numbers are not what I have seen. My 08 had 3. 73's in it, at 2200 rpm I was going 78 mph. My 2010 has 4. 10's in it, at 2200 rpm, I am running 74 mph. I tow a 16k GVWR fifth wheel that weighs in around 15k, with the 4. 10's, I noticed that it will hold 6th much longer before down shifting when running around 72-73 mph. Fuel economy is negligible, no real noticeable difference. But the 2010 just turned 24,000 miles, and seems to be running better every time I hook the fifth wheel up.

 

[Top Gun]

3. 73 differential gears are okay with the G-56 manual but are never suitable for towing with six speed automatics. The six speed automatics have overdrive ratios in fifth and sixth gears. 3. 73 gears will force the owner to tow at 80 mph or downshift to a lower gear to allow the engine to operate within the torque band.

3. 73's are never suitable for towing with A6's ? Can you expand on the reasons, or point me to a link with the info ?



Downshifting into 5th is good advice and would be what I'd be doing to keep it in the sweet spot range.

 

[Top Gun]

If we assume that 2200 is the "sweet spot" here is what you will see.



48RE w/ 4. 10's

3rd gear 49 mph

4th gear 71 mph



68RFE w/ 3. 73's

4th gear 54 mph

5th gear 66 mph

6th gear 85 mph



68RFE w/ 4. 10's

4th gear 49 mph

5th gear 60 mph

6th gear 78 mph



Below 45 mph I am not sure the difference is enough to compare, 2nd on the 48RE is nearly the same as 3rd on the 68RFE and there are 2 lower gears on the 68RFE to get the load moving, with 1st being 33% lower on the 68RFE so 4. 10 vs 3. 73 is really a 45 mph and up comparison.

Good info, thanks for this.



I currently tow with the A4 overdrive locked out ( because I believe my t/c has started to slip ) so to do a 55/60mph ish speed I'm spinning 2700rpm ish. I'm either going to do a new valve body and torque converter from Dave to my 04. 5 or just buy this 07. 5...

 

[HBarlow]

3. 73's are never suitable for towing with A6's ? Can you expand on the reasons, or point me to a link with the info ?

Downshifting into 5th is good advice and would be what I'd be doing to keep it in the sweet spot range.

All you have to do is review the road speed vs. engine rpm charts for each differential to see why 3. 73 is a poor choice with the six speed automatic.

Dodge tells you it is a bad choice with the downgraded towing limits placed on the 3. 73 and 3. 42. Only the 4. 10 gear sets earn the highest towing ratings.

Use of the 3. 73 gears gives up some torque multiplication and load startability in the lower gears then forces the driver to downshift and run in a higher gear while towing. Any fuel economy gains, if even measureable, are so small as to be no advantage.

So tell me, why would anyone want 3. 73 or 3. 42 gears for towing?

 

[AH64ID]

These numbers are not what I have seen. My 08 had 3. 73's in it, at 2200 rpm I was going 78 mph. My 2010 has 4. 10's in it, at 2200 rpm, I am running 74 mph. I tow a 16k GVWR fifth wheel that weighs in around 15k, with the 4. 10's, I noticed that it will hold 6th much longer before down shifting when running around 72-73 mph. Fuel economy is negligible, no real noticeable difference. But the 2010 just turned 24,000 miles, and seems to be running better every time I hook the fifth wheel up.

Those numbers were with 265/70's, here is the data on 235/80's. This is pure math based on published rev/mile and gear data. 74 @ 2200 would be 4. 44's in 6th gear, something seem's off for sure!



48RE w/ 4. 10's

3rd gear 50 mph

4th gear 72 mph



68RFE w/ 3. 73's

4th gear 55 mph

5th gear 67 mph

6th gear 87 mph



68RFE w/ 4. 10's

4th gear 50 mph

5th gear 61 mph

6th gear 79 mph

 

[Hoefler]

Those numbers were with 265/70's, here is the data on 235/80's. This is pure math based on published rev/mile and gear data. 74 @ 2200 would be 4. 44's in 6th gear, something seem's off for sure!



48RE w/ 4. 10's

3rd gear 50 mph

4th gear 72 mph



68RFE w/ 3. 73's

4th gear 55 mph

5th gear 67 mph

6th gear 87 mph



68RFE w/ 4. 10's

4th gear 50 mph

5th gear 61 mph

6th gear 79 mph

No way! Both of my trucks have been as I have stated.

 

[HBarlow]

Gear Ratio Calculator

Everyone can calculate the numbers for themself.

I've had this link saved for years. Not sure if I ever used it. The one I have used was created by former TDR member Ken Lenger who has it on his website along with lots of other good information.

 

[RVTRKN]

Although mine is a manual G56, I like the compromise between high RPM when not welcomed vrs lower RPM when empty. Its a matter of preference, as stated before, the duty cycle I had planed for my C&C was to haul RV's during the winter and convert the C&C to a service bed for my HVAC company during the summer. That would be a lot of city driving during the summer, and my 2500 with the NV5600 had the 3:73, from the purchase off the lot, it was OK, so my preference was the 3:73. Its worked well for me so far, except the 55 MPH when towing law here in California, would I do it again? Who knows what the future has to offer.

 

[AH64ID]

No way! Both of my trucks have been as I have stated.

Not sure why there is such a drastic difference. What size tires on your trucks? Have you verified the speedo (I think 10% error is acceptable by the mfgr) The gear math comes out dead on with my truck (speedo is calibrated with Smarty and GPS using long drives), and for an auto will only work when the torque converter is locked.

78 at 2200 with 3. 73's is what 48RE's with a . 69 OD do. In fact, the same is nearly true for 74 at 2200, takes a . 68 OD with 4. 10's.

Gear Ratio Calculator

Everyone can calculate the numbers for themself.

I've had this link saved for years. Not sure if I ever used it. The one I have used was created by former TDR member Ken Lenger who has it on his website along with lots of other good information.

That calculator is similar to what I built in excel several years ago, I just update the trans ratio's when I work with a different trans.

 

[JJPage]

If we assume that 2200 is the "sweet spot"

AH64ID, Do you actually tow constant @ 2200rpm?



Just asking, because unless I'm passing I rarely ever hit those revs. In fact anything over 1800/2000rpm my mileage goes to heck, and I do not need to be in that range to tow comfortably. I understand my truck(48re/3. 73, 35" tires) is not configured to the OP's question, but I tow all day long at 70mph/1800rpm, usually only slow down for traffic, corners and nighttime.



2200rpm maybe the rpm that maximum torque is available, glad I don't need it. With exception of my injectors, my fueling is turned back to stock while towing, or Smarty sw#1, because I lose my tire calibration when I return to stock.



I'm thinking you were just using 2200rpm for a mph correlation in each gear to compare... Jess