Why do you Cummins guys want more gears
I’ve heard a number of Cummins fans saying they are waiting for an 8 or 10 speed transmission before getting a new truck. Why? Does the Cummins struggle to get your trailer moving from a stop? Or are ...
Forum Discussion
There are two factors that I think many people fail to recognize about the Cummins/ Aisin combination. One is that the over all speed range of the Aisin 6 speed is very close to the Ford 10 speed. That is, 6th gear in the Aisin is the same ratio as 10th in the TorqShift and 1st gear in the Aisin is half way between 1st and second on the Ford 10 speed. The second factor is that the new Cummins has tremendous torque rise so it can handle much wider gear spacing than can the Duramax or Powerstroke without sacrificing performance.
When pulling a heavy trailer up a hill the required rear wheel torque is largely dictated by the incline of the hill and weight of the truck and trailer. As the truck slows down the power requirement is reduced but the rear wheel torque requirement doesn’t change much. If an engine has little torque rise, such as the Duramax the truck will continue to slow down until it can grab the next gear to raise the rear wheel torque in order to meet the demands of the hill. The Cummins on the other hand is able to produce much more torque as it pulls down so a gear change may not be necessary. For every 100 rpm the Cummins looses in rpm it gains nearly 29 lbft of torque compared to 10 lbft rise in torque per 100 rpm for the Duramax.
I think it is nicer pulling a hill using the engine’s torque rise vs having more gears and constant shifting up and down.
When pulling a heavy trailer up a hill the required rear wheel torque is largely dictated by the incline of the hill and weight of the truck and trailer. As the truck slows down the power requirement is reduced but the rear wheel torque requirement doesn’t change much. If an engine has little torque rise, such as the Duramax the truck will continue to slow down until it can grab the next gear to raise the rear wheel torque in order to meet the demands of the hill. The Cummins on the other hand is able to produce much more torque as it pulls down so a gear change may not be necessary. For every 100 rpm the Cummins looses in rpm it gains nearly 29 lbft of torque compared to 10 lbft rise in torque per 100 rpm for the Duramax.
I think it is nicer pulling a hill using the engine’s torque rise vs having more gears and constant shifting up and down.
