Transmission hard shifing

[AccessMaster]

I have a 3000MH Allison transmission. I changed the oil and filters per factory specs. The transmission now slams into 4th gear when downshifting from almost any speed. All other shifts are smooth up and down.
I am located in the Houston, TX area. Any and all recommendations are appreciated including where to take it for trustworthy service. Allison has recommended Stewart and Stevenson (where I purchsed the filter and fluid by the way).

[Pusherman]

Take it to an Allison certified shop. They can download any codes which may have been set.

[Mr_D]

Correct filters?
Correct fluid level?
Exhaust or Jake brake on?

[AccessMaster]

I got the filter kit and fluid as recommend by Allison.
The exhaust brake drops the transmission to 4th gear with a bang. That is the problem.
I reviewed the codes with Allison that I could see from the shifter. No help there.
Their recommendation was take it in.
I am not looking forward to this.

[bigmur]

does it shift hard when up shifting from third.you can take it to an allison dealer and they can put it on {fast adapt] which makes it relearn the shift pattern. But saying that nothing should of changed from just changing oil/filters. when you took filters down did you notice any metal in filters.

[lonestarace]

Hard downshifts are normal for a couple hundred miles after a fluid/filter change. Your allison transmission will "relearn" how to downshift and make the required adjustments all by itself.

[AccessMaster]

The oil and filters were grit free. No metal shavings on the drain plug. Everything looked good.
From time to time I got a rough shift into 4th gear in the past but not as hard as it is shifting now.