Best gear ratio for towing

[garyp4951]

I have a 03 2500 cummins srw quad cab with 3.73 gears, and wondering about changing to 4.10. I know it would tow better, but probably get less fuel mileage. Has anyone towed with these ratios.
Thanks, Gary

[goducks10]

garyp4951 wrote:
The pacbrake would be a great mod, but for $1500 I could buy a lot of brakes. Also I forgot to mention that I'm running 285 tires instead of stock 245 or 265, and this increase in height changes the 3.73 to around 3.55.

Actually going from 245/70/17 to 285/70/17 with 3.73's gives you 3.46.
Considering the tow rating for a 12 Ram 2500 CTD it drops the tow rating from 12,500 to 9500. Not sure how gear changes affect all years. But undoubtedly it will in some way.

[Me_Again]

garyp4951 wrote:
Chris you are right on the OD because when it shifts to OD at 45mph, there is a big drop in rpms. It is a 4x4, and would cost about $1000 to do it myself, or $2000 at the dealer. I have done several dana, gm's, and fords, but never an aam. I think they are the same as dana, and gm's.

Have you considered a Smarty programmer? Has your been beefed up. Early 03's had the 47RE and later ones the 48RE.

Chris

[garyp4951]

Chris you are right on the OD because when it shifts to OD at 45mph, there is a big drop in rpms. It is a 4x4, and would cost about $1000 to do it myself, or $2000 at the dealer. I have done several dana, gm's, and fords, but never an aam. I think they are the same as dana, and gm's.

[Me_Again]

rhagfo wrote:
We run an 11,000# 5er with an 01 and 3.55's and a 5speed. We do just fine pulling flats and can pull at five over the speed limit on the hills to the coast. You have a good gear ratio, I am assuming a 48RE auto, Pacbrake makes a unit for your truck!

http://www.thoroughbreddiesel.com/pacbrake/03-04-dodge-auto.htm

Having an exhaust brake is good having the best EB is even better. Seldom touch the service brakes towing in the hills.

The 47RE and 48RE have a taller OD ratio .69 vs the manual trannys .73. It was generally considered better for towing with these auto's to get the 4:10 gears. At 2000 RPM's I am doing around 63 MPH which is a good freeway tow speed for me and my 4:10's. Also the manuals have much lower reverse and 1st gears vs the autos.

Now if OP truck is a 2x4 then swapping gears might be OK, I would not however spend the money to do it on a 4x4.

Chris

[maxwell11]

my 2005 dodge diesel does fine pulling my tow behind camper.
it has the 3.73 ratio, has tons of power and torque.
still gets good mpg

worst thing with it, you will find that you chew a lot of rubber off those back tires with that ratio and power.

but, I am not pulling backhoes or super heavy eq or a camper trailer near the tow limits of my truck, then I might want the 4.10 ratio.

your ratio should fit the job,

check out the ratio on some of these new trucks, its even higher than 3.73, maybe 3.42 or 3.27 guess they have so much more power and torque than my old 5.9 diesel.

[garyp4951]

The pacbrake would be a great mod, but for $1500 I could buy a lot of brakes. Also I forgot to mention that I'm running 285 tires instead of stock 245 or 265, and this increase in height changes the 3.73 to around 3.55.

[rhagfo]

We run an 11,000# 5er with an 01 and 3.55's and a 5speed. We do just fine pulling flats and can pull at five over the speed limit on the hills to the coast. You have a good gear ratio, I am assuming a 48RE auto, Pacbrake makes a unit for your truck!

http://www.thoroughbreddiesel.com/pacbrake/03-04-dodge-auto.htm

Having an exhaust brake is good having the best EB is even better. Seldom touch the service brakes towing in the hills.

[2500_Grunt]

4:10's will give the OP better use of 4th gear in the 4 speed tranny and keep running temp's down by not lugging the engine or by running high 3rd gear rpm's at 60 mph ish.. If you are not running any 6% grades or higher then you won't benefit much. I need to do the switch and can see with gauges and slight mods to the truck where I'm actually at. The above statement is true regarding hp and torque but operating temp's are another thing to consider (egt's) especially if you have done any engine mods to make it run hotter/more powerful. Pulling a hill here in AZ in 4th and downshifting into 3rd reduces my egt's about 2-300 degrees. I also burn more fuel but it's def. happier.

[Water-Bug]

Gassers love higher rpms to develope the ponies. Diesels on the otherhand develope the ponies at much lower rpm. My 2012 RAM Cummins with 3.73s, cruises at 60mph right at the 1400 to 1500 rpm sweet spot of max hp/torque. As a result it rarely feels the need to downshift to maintain the cruising speed. Changing to 4.10s would decrease my speed at 1400 rpm by 10% putting me at 54 mph at max hp/torque. Downshifting puts the engine completely out of the sweet spot. I'd rather cruise at max torque and let the tranny handle the very rare occasion that I don't have enough torque to maintain 60mph than have max engine performance at 54mph.

[C_Schomer]

I love my 4.1s. How much weight do you tow and how often and how far? I went from a 97ctd 3.54 to this 03ctd 4.1 (similar mods/power) and the 03 will handle way more weight and do it easier on top of it. My worst mpg empty is 18.3 no matter if it's city or long road trips and I get 12 towing my 15kgvw 5er. My 03 was also my only vehicle for 8 year and I still would rather have the 4.1s. I bought an old grand Cherokee just to keep the miles off the truck. Craig

[john_bet]

garyp4951 wrote:
I have a 03 2500 cummins srw quad cab with 3.73 gears, and wondering about changing to 4.10. I know it would tow better, but probably get less fuel mileage. Has anyone towed with these ratios.
Thanks, Gary

Mine has 3.73s and I am happier than a bull in a pasture full of heifers.

[whsk]

you already have the "RIGHT" tow gearing with the Cummins!-whsk

[garyp4951]

I agree the Cummins has so much torque it would not know the difference, except at a truck pull contest. My Silverback weighs around 11,500 and seems like a good match for the truck. As stated an exhaust brake would be great, but don't think it is an option for my truck.

[Ivylog]

With a 6 spd tranny going to a 4.10 with a diesel is backing up. Want a 4.10, keep it from going into OD. Granted a 4.10 will give you better 0 to 10 MPH times but after that it will not make any significant difference. I sometimes gross over 26,000 lbs with a 3.73 and even in rolling hills I use OD.

[retispcsi]

I had a 3:73 in my previous Ram CTD it pulled very well in the hills and mountains that I was in. New Ram CTD has a 4:10 pulls the same on the flats. and maybe a little easier in the mountains but I also have tow/haul with built in exhaust brake. That may help also. Fuel mileage towing is about the same. If the truck had a 3:73 I would leave it alone. If you order a new one get the 4:10.