Gearing with G56

[LDobie]

Made a spreadsheet comparing the NV5600 and G56 and the speed at RPM increments for each gear, and like I've seen on here, the G56 with 3. 73's is very similar to the NV5600 with 4. 10's as far as 6th gear goes. Both are right at 70mph at 2200 rpm and 75-76 at 2400.



I wonder if they will offer 3. 55's or 3. 43's for '06?? 3. 43's seem like they would be perfect for me as I don't do any real heavy hauling. They would run right about 70mph at 2000 rpm. Does anyone know if you can buy aftermarket gears for the 3/4 ton's, I haven't had much luck finding any. Thanks alot.

 

[Tim]

This has been discussed quite a bit. I don't think the gearing change would ever net a significant enough MPG improvement to pay for itself. That's just my opinion as of now though.

 

[JLovas]

Because I do a lot of interestate driving (75 mph speed limit) I think my 3. 73's with the NV5600 is geared too slow, and your right, the new G56 is going to be worse. I don't know why why an engine that develops peak torque at 1600 RPM has to be running 2400 RPM at 75 mph???



The increase in fuel economy from an aftermatket overdrive has been debated many times, and its unclear, at least to me, if the savings will be there over time. Other advantages would include quieter cab at highway speeds, and you'd think that the slower engine speeds would reduce engine wear. Maybe in the end its worth it, but I'm not ready to fork over the $3000+ for a overdrive kit, plus the cost of shortning the drive shaft. A little too spendy for me.

 

[SRadke]

Taller tires helps the gearing, unfortunatly with the the added height and decreased aerodynamics your mileage will remain about the same



-Scott

 

[LDobie]

I couldn't agree more, that a motor with max torque at 1600 has no business cruising at 75mph at 2400 rpm, unless you are toating a big load. Especially when your redline is only 500 rpm higher. In comparison to my Dakota, thats like running down the interstate at 3500-4000 rpm, and this motor has a redline of about 5200. The '05 NV5600/610 that I drove 2 weeks ago seemed to be as responsive at 1800 as at 2400 to me.



Aero is huge, there is no question there. Even my little Dakota is extremely aero and speed sensitive. At 75, with no "drafting" help, I see 15. 5-18 max mpg, but with some good drafting help, it can go up to 20-21, I bet the big ride Rams are similar. Some aftermarket company out there has got to make aftermarket gears for these big rigs, but it's kinda disheartening to spend another $800-$1000 immediately on a $40K truck

 

[klenger]

I updated the Excel gear speed calculator on my website to allow comparrison of two or more (Dodge) transmissions, including two of the same type with different gear ratios and/or tire sizes. Just hide the columns for the transmissions you are not interested in. The worksheet includes charts for the NV4500, G56, RE47/48, or NV4500.



Download it at http://www.klenger.net/dodge/general-reference/gear-speed-calculator.xls