Clack Noise Upon Shift...Allison

[agraves138]

Good evening all, 

 

2016 Silverado 2500HD 6.6L Allison Trans. 59K miles

 

For a while I've noticed that sometimes (not always) there is a noise that can be heard from inside the cab when the transmission shifts gears. Best way I can describe it is a "clank or tick" type noise. I generally happens when the truck is either under load such as going up an incline, or if I accelerate a bit harder than normal, usually I'll notice in the 2-3 shift, but somethings also in the 1-2 shift. 

 

The transmission doesn't shift late, or even hard, but it makes this audible noise, and it can even be slightly felt through the truck when it does occur. 

 

In hoping to solve the issue:

I recently had the dealer perform a transmission service (fluid, inner and external filter). Noise still present.

I recently changed the front differential fluid. Noise still present.

I recently changed the rear differential fluid. Noise still present. 

Next up I'll be doing the transfer case fluid. 

 

Checked the U-joints, and I don't seem to find play or excessive play in the shafts/joints. May a tiny bit in the front drive shaft where it comes out of the transfer case, but even that seems minimal. 

 

Is anyone else experiencing this? Is this normal for the Allison/Duramax? This is my first diesel, so maybe it's just something I'm not used to. But if it is an issue I'd like to fix it early. Thanks! - Ant