6L80 shifting adjustments

So my tune is working really well. Just cannot for the life of me get it to shift the way it should under very light throttle on the 2-3 and 5-6. If I take off and keep constant or heavier throttle, shifts nice and firm, like I want. If I accelerate and then let off or change the throttle percentage, it will almost slip into 3rd or 6th, but not all the time. temp doesnt matter. Doesnt matter if its on E85 or 93 either. Im assuming it is a command issue, or torque. Can post tune if needed. Anyone dealt with this? Other than that, truck screams.

Trans tuning can be a PITA.

As with any tuning questions, going to need a tune and a log, and thats where tuning a trans gets difficult, as in getting the log during the shifting issue.

are you trying to tune it with pressures or by shift time. Cause shift time is how you want to do it.

tuning with shift times. Im going to get a log at lunch today and post, along with the current tune. Appreciate all the help!

Attachment 143647


Heres the tune Im running now. If someone can point me in the right direction, Id really appreciate it. Not looking for a handout, just a general direction of what Im missing here. thank you!

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Originally Posted by Estep40511

Attachment 143647


Heres the tune Im running now. If someone can point me in the right direction, Id really appreciate it. Not looking for a handout, just a general direction of what Im missing here. thank you!

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Try this file. I made a few adjustments to your tune. Attachment 143651

can I adjust the inertia factor profile up to get the feel I want? I didnt take a log because I couldnt get it to act up, going to try today when I leave work.

I wouldn't touch the inertia tables at all. GM did a pretty damn good job with those. I always start with shift timing and possibly adjust the pressures up to +20% on a stock trans with a stock TCC. Take a look at the adjustments I made to your file and try it out and she how it does. Don't forget to reset your adaptives with VCM scanner as well.

I think I have it shifting nice and firm now. If anyone can steer me in the direction of getting it to shift quicker....Id appreciate it. Is it possible to get it to shift like the 6 speed in the Vette???

Well I lowered my shift times way down to .20 or .1934 in the 0 and negative torque areas and it fixed my soft shift under light throttle. weird it didnt happen everytime. I have the Sonnax zip kit and ZL1 converter in my 6L80 also, and it only has about 10,000 miles on it. So I couldnt figure it out lol. Im assuming to get it to shift harder or softer, you mess with the output torque factor? Just playing with things and seeing how it likes it.

shift time is usually all you have to do, after that then start upping the oncoming pressures 5-10 ft lbs at a time, and that is usually only if it isnt meeting the desired time. To delve deep is to go into the VTT tables, but if it is a "non- cammed" engine, then stay away from VTT.

You can touch inertia tables also. But start with the basics first. Honestly a lot of "big name tooners" on the gen V only touch the inertia.

when you adjust the inertia, is a lower number a faster shift or firmer? or a higher number? I cant find the information on that, thats clearly understood anyways. Guess I can mess with it and see lol

If your talking about inertia factor profile

It's just a reference to another table that adds (subtracts really) to the shift time tables. It happens in "desired output torque factor"


Shift time is where the money is made. However you get there.

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Originally Posted by Alvin

If your talking about inertia factor profile

It's just a reference to another table that adds (subtracts really) to the shift time tables. It happens in "desired output torque factor"


Shift time is where the money is made. However you get there.

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That makes perfect sense. Im going to adjust those now. My shift completion times all look good. just trying to adjust it how I like it to shift. I like the firmer shifts, but I like asking before I try....so I dont melt the old 6L80 down lol. thanks for the help!

Attachment 144133

Heres my adjustments so far. Let me know what ya think. Im all ears