6L80 WOT Shift RPM vs WOT Shift Speed

[KYSilverado04]

I'm looking to do some minor changes to the shift points on my 2011 GMC Sierra 5.3L with the 6L80E transmission. Part throttle seems straightforward enough and WOT would appear to be but there are two sets of WOT tables, one for shift speed and one for shift RPM and they don't seem to really line up.

Example, given the tires sizes, gear ratios, and final drive ratio one can convert road speed to engine speed (assuming the torque converter is locked) and vice versa.

For NORMAL transmission mode:

WOT Shift Speed:
1 -> 2 Shift 28 MPH (~4000 RPM)
2 -> 3 Shift 55 MPH (~4700 RPM)
3 -> 4 Shift 89 MPH (~4900 RPM)
4 -> 5 Shift 118 MPH (~4900 RPM)
5 -> 6 Shift 160MPH (~4900 RPM)

WOT Shift RPM:
1 -> 2 Shift 5525 RPM (~38 MPH)
2 -> 3 Shift 5425 RPM (~63 MPH)
3 -> 4 Shift 5425 RPM (~97 MPH)
4 -> 5 Shift 5200 RPM (~122 MPH)
5 -> 6 Shift 5200 RPM (~167 MPH)

Obviously there is quite a bit of discrepancy here. So the question is where do both sets of tables come into the equation? If it always used shift speed then the rpm table would be rather redundant, and likewise if it always used RPM the shift speed would be redundant. Can anybody give any insight as to what conditions must occur before it references one table over the other?

[village_idiot]

The way the WOT shift sequence happens is, it has to have BOTH requirements met before it initiates a shift. (with the exception that SOME will lean more towards paying attention to MPH only on the 1-2 shift).

An example of what SHOULD happen if you go WOT from a stop... as the RPM is climbing in 1st it should see the 28mph first (first requirement met), and then when it sees 5525RPM (second requirement met), it should initiate the shift.

It will help you understand better if you try not to associate an RPM with the MPH, and vice versa. Just consider them 2 different things that have to be checked off the list before shifting.

When tuning the shift points, watch the MPH/RPM in the scanner for each shift. If you see that it shifted earlier than the RPM that you would like, then raise the MPH until it shifts when you want. Do the opposite if it overshoots the shift RPM

[KYSilverado04]

Very interesting. May I just take a moment to say THANK YOU for actually answering the question at hand instead of saying "well have you done a search," "why would you want to do that," or "I don't understand that so you clearly don't need to either." It's good to see that there are still a few people out there willing to be helpful!

I love that the truck has the tow/haul feature and it is very handy for that purpose. For regular driving I wouldn't mind some of the behaviors of tow/haul but some would annoy me if I'm not towing (hill assist with cruise), etc. So what I was ultimately looking to do was kinda split the difference on the shift points. I tossed both the "Normal" and "Pattern A" mappings into Excel and had it calculate a middle point, which will be my new "normal" pattern. That's all well and good for part throttle but the WOT behavior was a little confusing. Your explanation makes sense and will help me dial in the behavior I desire.

One other quick question.... Do I need to do any kind of trans re-learn procedure if I'm only changing the part throttle and WOT tables?

[village_idiot]

I try to remember that everybody is new at some point. On the trans relearn, that will only be necessary when/if you change trans pressures. Just shift points will not affect that

[KYSilverado04]

That's a great attitude that I wish more people had. I'm actually not very new to tuning in general, I'm just new to tuning this thing. Back a long time ago in what seems like another life I made really good money tuning speed density chip cars. Fast forward several years and I had a 2004 Silverado that I was just starting to figure out when it had an unfortunate run-in with a tree. https://www.youtube.com/watch?v=T1NUX4i1bOE

To say the tuning of the 2011 is just a tad more complicated is a wee bit of an understatement! I'm learning, slowly, but I just don't have the time to tinker with it all day long like I used to.