2003 TRAILBLAZER LT, 4.2, 4L60E. hard 1-2 shift

[Jburkhart]

what can i change to lessen the hard 1-2 shift on this transmission. this is the only issue i have with transmission. i just got mpvi3 yesterday so this is all new to me. thanks for any info. attached is the current tune, i believe stock

[TheMechanic]

First things first. Before you go messing with a stock tune, does it have a transmission, TAC, or any other codes in the PCM? If so diag those first before messing with the tune. Those do not typically have a harsh shift when everything is bone stock.

[Jburkhart]

0 codes and i forgot to mention po said they put in a corvette servo.

[TheMechanic]

That servo will firm up the shifts.
Shifts are pretty subjective. Do you have a stock vehicle to compare to? You could soften it up with some adjustments.

[Alvin]

I don't like to undo shift firmness from shift kit type parts like that.

I'd go back to the OEM servo to get the shift you want.

[TheMechanic]

I don't like to undo shift firmness from shift kit type parts like that.

I'd go back to the OEM servo to get the shift you want.

Totally agree. I tell customers no problem on aftermarket clutches, zip kits, etc etc but no mechanical shift kits given the ability to put the shift kit in electronically in a far safer better manner.

[blindsquirrel]

screenshot.10-08-2023 04.45.44.png

[Jburkhart]

Thank you. I’ll try this weekend

[blindsquirrel]

The 70E servo might be a better choice. (combined with adding some TM at the 1-2)

https://www.sonnax.com/tech_resource...for-the-4l60-e