A40 TCM Tuning

[08lmm72mm]

Hey guys,

I'm modifying my stock TCM tune so it has slightly higher shift points going into 5th and 6th gear so my truck doesnt bog and blow black smoke with my turbo. Now I've adjusted my part throttle 2-3, 3-4, 4-5, and 5-6 up shifts and the 6-5, 5-4, 4-3, and 3-2 downshift to how I want them in Pattern A, now I'am curious if i need to adjust anything in the TCC Apply/Release speeeds for each gear as well?

My goal here is to have the truck shift a little higher in part throttle driving and not have the truck shift into 5th until 56mph and not have 6th shift until 75mph. The reason is with 35s and the 72mm turbo is that it shifts into those gears too early for where the turbo is happy. Thanks for any help.

[kyledeg4]

Dont bother with 56mph. do 63 for 5th and 75+ fpr 6th. I have a 369 and 5th locked at 56 lugs.

[killerbee]

Hey guys,

I'm modifying my stock TCM tune so it has slightly higher shift points going into 5th and 6th gear so my truck doesnt bog and blow black smoke with my turbo. Now I've adjusted my part throttle 2-3, 3-4, 4-5, and 5-6 up shifts and the 6-5, 5-4, 4-3, and 3-2 downshift to how I want them in Pattern A, now I'am curious if i need to adjust anything in the TCC Apply/Release speeeds for each gear as well?

My goal here is to have the truck shift a little higher in part throttle driving and not have the truck shift into 5th until 56mph and not have 6th shift until 75mph. The reason is with 35s and the 72mm turbo is that it shifts into those gears too early for where the turbo is happy. Thanks for any help.

Your Torque converter isn't affected. If you have a light duty, it locks/unlocks in 3rd. You are on the right track. Just prevent hunting by created a large gap between your upshift and downshift speed. The 6 speeds have notoriously poor power band shifting. It's an EPA and sound emissions thing. Having 1200 rpm at 55mph can't pass anything until you wait 5 seconds for a downshift and turbo spool. Sometimes a double downshift, just hideous factory settings.