2021 HHOO Cummins/Aisin trans downshift funkyness

[Scottly]

Noticed something on my 2021 3500/Aisin trans...When you are coasting to a stop, getting below 10MPH, into the speed range where it should downshift from 2nd to 1st gear, it seems to take it's sweet time between those gears...Literally, several seconds after it comes out of 2nd and into 1st. If you decide to accelerate during this time, the engine will wind up and slam into 1st. This normal? Hard to tell as this is a naturally clunky box driving around town. This issue reared it's head when I was up in the mountains last week.

 

[Billet Bee]

Mines a 20 model and had done that since new. I just tought myself not to hit the accelerater to early when coming to a stop and no problems since, but annoying yes. Theres a price to pay for us having the big hauling aisin.

 

[tjfdesmo]

Welcome to the world of the Aisin 2-1 "slam shift". Wait 'til you get the 2-3 shudder with a heavy trailer behind it. The Aisin is a very durable unit, but pretty unrefined in operation.

 

[JFV1134]

I have the Aisin as well and notice that the 2-1 downshift takes longer than the others. You can feel the engine rev a bit to accomodate the change in torque converter RPM. It "slumps" down into first. Usually, the whole process takes about half a second. I don't mind in the least, though. It is how it is when you are using a medium-duty transmission.

 

[CLOUDL1GHT]

Yup mine does this as well. It likes to lurch a little bit once it does get into 1st gear too. I also have the Aisin "chirp" when accelerating hard. It is an unrefined medium duty transmission in the end.