2016 3500 C&C shifting

[jmorse]

I took delivery of a new 3500 C&C, 6.7L, Aisin trans,4.10 gears and max tow package about 3 weeks ago. Now that I have the body built and have been using the truck (548 mi.) I find the transmission down shifts on every small knoll on the highway (1-3 mph drop in speed). It doesn't matter if it is in tow/haul or not. Doesn't matter if the cruise is set or not. It will do it empty or when towing. My '07 was a 6spd manual, so I have nothing to compare it too. But our '15 2500 with the 68rfe/3:73 gears and 18" tires doesn't do this. I just don't like the idea of the transmission shifting so much. I'd think the engine should work a little before a downshift. Is this common with the Aisin?

 

[Hoefler]

What RPMs are you running when it downshifts?? If you're below 1800-1900 it will down shift when it senses a load increase. Turn on the Tow Haul and manually downshift it to keep the RPMs around 2000, this is where it likes to cruise at. Mileage will go up and will hold the gear better.

 

[jmorse]

Thanks for the response. The RPM @ 65mph is around 1700-1800.

 

[cerberusiam]

Thanks for the response. The RPM @ 65mph is around 1700-1800.

That is why it downshifts, way on the backside of the TQ peak. When it sense load it will find the correct rpm but that slow will cause more shifting. 1900-2000 rpms and it will be a lot happier.