I recently purchased a 2002 2500 with the cummins. it has an automatic... 3 spd with overdrive. i do a lot of highway travel, (600-1200 miles a clip) and at about 70mph, not towing a load, i am at about 2100 rpm. is there a way for me to tune the transmission to lower the rpm at highway speeds? just looking for any way to increase my mpg rating. Thanks

 

No, all that would do is change the shift points, which won't affect highway cruise RPM.
You're already locked up and in overdrive by then.

Bigger/smaller tires, or changing the gear ratio (in both diffs in a 4x4) is the only thing you can do.

That RPM suggests you have the 4.10, good for towing, bad for mileage.
3.55 will get you better mileage, but towing power will suffer.


phox

 

so do i want to find 2 ring and pinions? it is a 4x4, and who is a good supplier for new gears?
thanks again

 

I'd swap axles with you to get the 4.1's and give you the 3.55's. I will be in the lower 48 in August???

 

august i will be in mid florida...
this would have to be a close setup swap, but i would be happy to swap with you...
how many miles are on your drivetrain?
but yeah! for sure!
i would be in florida till the mid september in reality, i work for a traveling company, so i cant transport the truck from city to city, this would have to be tight... i cant stress that enough! please email me guyssets@hotmail.com or 2039485324.
Thanks alot, this may save me alot!

Guy