Gear Ratio change

[134x4ctd]

Has anyone out there changed out the 3.42 gears yet? I tow around 12000lbs and sometimes find it a struggle to start off on a steep hill. Can the gears be changed? Does the truck need to be flashed or anything else? Do the 3.73 gears make a big enough difference? It tows fine once you get the weight moving. My truck is a 2013 2500 4x4 crew cab long bed 68rfe. Thanks

 

[photowrite]

I've yet to have a diesel re-geared, but I've had the gears changed in a few gas rigs, two that I still own. One had 3.73:1 and the other 4.30:1, both were changed to 4.88:1 and run only a 33-inch tire.

One should be conceded/aware about going too low, but if/when I re-gear I always want to receive a substantial change for my money. If I had 3.42:1 (and I do in my '14 2500) and was going to do a gear ring-and-pinion swap, I'd probably go to 4.10:1.

 

[mpaulson]

I agree with Photowrite, I'd go 4.10's. On my last truck I went from 3.73 to 4.56 and that was perfect for towing, but not so nice when you wanted to cruise a bit above speed limits while not loaded.

 

[Jim W]

Has anyone out there changed out the 3.42 gears yet? I tow around 12000lbs and sometimes find it a struggle to start off on a steep hill. Can the gears be changed? Does the truck need to be flashed or anything else? Do the 3.73 gears make a big enough difference? It tows fine once you get the weight moving. My truck is a 2013 2500 4x4 crew cab long bed 68rfe. Thanks

Are you sure it is the gear set and not the ECM of the truck. If I remember correctly I think the engine/transmission software is now being design to prevent the full HP/TQ from being applied at initial starting (launch) of the truck. This is to prevent transmission failures due to the higher HP/TQ that is now available for use. I might have read this in the TDR quarterly publication also.

Maybe one of the Ram techs or one of the writers in the TDR publications can chime in to say if I am correct or full of it!

Jim W.

 

[Brocky]

Jim may be right and modern day technically workable.

BUT, If your only main problem is getting started on hills, An old school underdrive auxillary mounted behind the trans might be cheaper, easier, and you would still have your top gears for cruising, especially when not towing. Just read the 4X4 and that complicates it..

 

[mpaulson]

There is definitely torque management in the lower gears. When I went to the 4.56 gears it literally felt like you were starting out in low range, no effort at all to get rolling and that was at 24,000 lbs combined total and on soft ground allot in fields where we camp and that was with the 68 RFE in my last truck. The lower gear set will multiply the torque more regardless of the ECM management. And you don't need to to any programming changes when you change a gear set, the speed in measured off of the rear ring revolutions which will be the same regardless.

 

[Stab]

Really like my 3.73s for towing 25k gross.

 

[Brocky]

I am with Stab.. My 3.73's are a great all around gear. Plenty of pulling power loaded towing and decent fuel mileage when not towing.

 

[Cummins12V98]

Try driving around in 5th that way you can tell if you can live with 4:10's because that is the RPM's you will be running in 6th with the 4:10's.

 

[AH64ID]

Since starting is your issue then a gear swap would be worth it. 3.73's are a 9% change and 4.10's are a 20% change.

Do what Cummins12V98 recommends and lock out 6th for a while and see how it works out for you. If it's good then go 4.10's.

My $0.02, if I bought a new truck today it would have 4.10's swapped into it before I left the lot. I do lots of low speed towing at 19-20K GCW on some steep and winding dirt/gravel/paved roads where I may not hit 15 mph for 10-20 miles and that is where the 4.10's are much better than 3.42's. Once rolling it's a matter of gear selection so a gear swap is really only needed for those folks who spend a decent amount of time at lower speeds where there is nothing lower than 1st.

 

[RVTRKN]

The costs are prohibitive with 4x4, my choice would be to install Dyna-Track front hubs and leave them unlocked and have 4x4 in low range until moving then to high range or 2x2. If your on gravel you'll be in 4x4 any way and lock your hubs.

 

[Cummins12V98]

Since starting is your issue then a gear swap would be worth it. 3.73's are a 9% change and 4.10's are a 20% change.

Do what Cummins12V98 recommends and lock out 6th for a while and see how it works out for you. If it's good then go 4.10's.

My $0.02, if I bought a new truck today it would have 4.10's swapped into it before I left the lot. I do lots of low speed towing at 19-20K GCW on some steep and winding dirt/gravel/paved roads where I may not hit 15 mph for 10-20 miles and that is where the 4.10's are much better than 3.42's. Once rolling it's a matter of gear selection so a gear swap is really only needed for those folks who spend a decent amount of time at lower speeds where there is nothing lower than 1st.

With the heavy loads it's all about getting off the line. I towed a lot with the 3:42's in 5th and the RPM's were around 1700+ at 62. The cab noise was fine so that clinched it for me when I ordered the 15 I went with 4:10's and Aisin and VERY happy I did!

 

[AH64ID]

With the heavy loads it's all about getting off the line. I towed a lot with the 3:42's in 5th and the RPM's were around 1700+ at 62. The cab noise was fine so that clinched it for me when I ordered the 15 I went with 4:10's and Aisin and VERY happy I did!

I'll bet you are quite happy with that decision.

I know why Ram decided to drop all gears but 3.42 in SRW, but I still don't agree with it.

 

[134x4ctd]

Thank you for all of the replies. Second question is have any of you guys with 4.10 gears done any unloaded highway driving and still gotten above 20 mpg? I do tow but I also drive unloaded as well and would hate to give up the excellent mpg that I currently get.

 

[photowrite]

You will definitely be giving up some unloaded MPG with the lower diff ratios. As suggested by other, use 5th instead of 6th. To see the theoretical difference, do an all freeway, empty baseline mpg test for at least 50 miles round trip, once using 6th, and then again using only 5th for the top gear. This should give you an idea of the fuel economy reduction. You may lose 1.5-3 MPG.

 

[AH64ID]

You will definitely be giving up some unloaded MPG with the lower diff ratios. As suggested by other, use 5th instead of 6th. To see the theoretical difference, do an all freeway, empty baseline mpg test for at least 50 miles round trip, once using 6th, and then again using only 5th for the top gear. This should give you an idea of the fuel economy reduction. You may lose 1.5-3 MPG.

With modern machining, oils, and ECM's I doubt there is even a 1.5 mpg difference let alone 3mpg. Modern engines just don't burn enough more fuel at increased rpms to make that difference, especially considering the engine has a 20% mechanical advantage.

There will be a increase in fuel burn, but aside from fleet use I am not sure it's enough to write home about.

 

[RVTRKN]

Then 3:73 should be your choice to help the 50/50 use of the truck. That's why I ordered my C&C with the 3:73 due to 50/50 use, but in the end I mostly tow with it now, should have gotten the 4:10. With the 3:42 the new truck runs to low of an RPM cruising around city and causes an awful pinging condition at 45 MPH and 1100 RPM, but on the freeway, its 1500 at around 65 MPH, which is nice

 

[Wertles]

I have the 4.10's and I'm lucky if I see 16 mpg unloaded at 70mph thruway driving. I'm a dialog so there goes a mpg or 2 on top of the gearing. My trailer was 18000 pounds loaded and I never had to worry about getting started. If I had to do it all over again, I would get the 3.73. I think it is a good compromise to towing and empty driving.

My advice is keep what you have. The cost of regearing plus the cost of increased fuel will be a high price to pay just so you can once in a while get going a little faster when towing while going up a hill. For you, this seems as described as an occasional thing, not an everyday, all day thing.

 

[Dieselnerd]

I have the 4.10's and I'm lucky if I see 16 mpg unloaded at 70mph thruway driving.

That's around what I get with my 4:10 Dually too and I'm happy with it. It's better than my 2005 SRW with 4:10's got. It pulls my trailer better than I expected too.

When I'm not towing I usually have my Lance camper on board. With the 4:10's it never feels sluggish. With the Aisin 6 speed and 4:10 ratio it never lugs or pings in the city and the rpms on the highway are not that high either.

 

[Mingoglia]

I think 16mpg is pretty good for something that weighs over 4 tons. My truck comes in in two days and I got the 4.10. In the back of my mind I'm thinking the 4.10's are going to be a challenge since unloaded I drive a lot faster than 70. On my 2nd gen I have the 3.54 gears. When I tow I get 14mpg, when I'm empty I get 10mpg. You decide how I get such "bad" fuel economy when 12,000lbs lighter.