Lugging?

[HouseMouse]

Solo or Towing... At what RPM should you be mindful of to down shift to eliminate Lugging the drivetrain? I "think" it's about 12-1300 RPM. Just would like to hear what everyone thinks. Thanks.

 

[CdnHO]

Solo or Towing... At what RPM should you be mindful of to down shift to eliminate Lugging the drivetrain? I "think" it's about 12-1300 RPM. Just would like to hear what everyone thinks. Thanks.

Let the transmission decide.

 

[MacksRam]

Let the transmission decide.

That is right--let the tranny take care of that.
When you are towing and put in Tow/Haul mode--it will not "lug" anyway--the ZF 8 spd tranny will automatically downshift to prevent lugging. IF you are towing heavy and driving slower (say 50 mph)--the tranny will not let it go in 8th gear. Even driving empty lugging should not be an issue. I say that because the ZF does an EXCELLENT job of keeping itself in the center of the Cummins torque powerband.

 

[CdnHO]

That is right--let the tranny take care of that.
When you are towing and put in Tow/Haul mode--it will not "lug" anyway--the ZF 8 spd tranny will automatically downshift to prevent lugging. IF you are towing heavy and driving slower (say 50 mph)--the tranny will not let it go in 8th gear. Even driving empty lugging should not be an issue. I say that because the ZF does an EXCELLENT job of keeping itself in the center of the Cummins torque powerband.

If I recall correctly in Tow Haul it uses 1 thru 7 gears. In "normal" mode it uses 2 thru 8. All sorts of sensor inputs determine the correct gear. No sense the driver second guessing.

 

[LouNY]

I usually use the shift up/down buttons to make the current gear visible and it always shows first (1) unless I've felt it shift up getting going in the driveway.

 

[Shotgun]

There is a setting where you can elect to show which gear you are in at all times. Also, when towing my fiver, it will go into 8th gear at highway speed. The conditions have to be right and speed at a good clip.

 

[HouseMouse]

Thank You for the responses thus far. Ok, now the twister.... How does the Gear Limiter factor into the equation?

 

[oetkb00]

If I recall correctly in Tow Haul it uses 1 thru 7 gears. In "normal" mode it uses 2 thru 8. All sorts of sensor inputs determine the correct gear. No sense the driver second guessing.

Tow/Haul mode uses all 8 gears. It's quite gratifying to have a GCVW of 17,100 lbs, be cruising up a 3%-ish grade at 72 mph, and purring along at approximately 1650 rpm

As an aside, the cruise control in our '26 2500 Cummins running in Tow/Haul mode is much better than that which was in our '19 1500 5.7. Going down a grade it uses the engine brake extensively (assuming it's on) and will downshift when needed. The 1500 never downshifted on its own.

 

[MacksRam]

Thank You for the responses thus far. Ok, now the twister.... How does the Gear Limiter factor into the equation?

This is not a twister---say you "limit" the gear to say 6th gear---the tranny will not shift past 6th gear--it is that simple. Honestly, I see Gear Limiter feature used very seldom--for example: Pretend you are pulling a very heavy load up a steep hill (i.e short distance)--in this case you would want the tranny to stay in a low gear. You would want this because higher RPM causes more clutch pressure (to prevent slippage) and keep Cummins in the torque powerband.

 

[LouNY]

I frequently limit mine to 5th and even 4th some days on our back roads, now need to kick it up to 5th or 6th at 35 mph. or even 45.
Plus I'll most days button it down to 1st to go down or up the driveway.