ZF8HP995, 2->1 Downshift Help

Hello Folks,

I have an annoying downshift clunk going from 2->1.
When:
-All modes (normal, sport, perf).
-Trans is warmed up above about 125F (does not occur when trans is cold).
-Does NOT occur in 3->2. I have 1st gear tuned out for Track mode launch. Similarly, SNOW mode starts in 2nd and does not have the issue.
-Occurs at VERY low speeds, like when slowing from 4-1 mph.

Hardware: (2018 Jeep Trackhawk)
Trans- ZF8HO95, built by Southern Hot Rod (War Viking).
Transfer Case: built by Paramount Performance.
Rear Diff: Rebuilt.

I do not think there is play in the driveline components.

Looking / comparing a stock 2020 trans TCM file to mine, there are some differences in the many of the 2->1 downshift Parameters: inertia mode downshift, oncoming clutch pressure, oncoming clutch pressure ramp, offgoing clutch pressure, offgoing clutch pressure ramp, trans fill pressure offset ramp, nominal slip time.

I'm tempted to copy all the 2->1 downshift parameters from the stock 2020 file to my 2018 file.

Comments? Suggestions? Warnings?

OTHER: Can anyone please post which clutch pairs are used for each gear change?

Thanks All !!

I was having this issue also with my Audi A4, but shifting from 3-2 @ 5km/h.

What I did is set the downshift to 2nd at 5rpm (OSS) lower then when the TC unlocks around 12km/h, and it's a lot smoother now.

You could also set 1st gear down shift at 5rpm (OSS) and it shouldn't shift into 1st until you're stopped.

Hope this makes sense, and helps!