6l80 2-3 Bind

[ns158sl]

I havn't noticed much of an issue with this transmission after being rebuilt, but now since my fueling and TQ tables are more inline from the dyno, I am getting a 2-3 bind/tie-up. I did remove the wave plate in the 35R as per sonnax. So far the consensus is that the wave plate needs to be there.

Ive played with almost all the settings in HPT with no luck. Well I should say, I don't have the bind at first, then the trans "adapts" to a tie-up. Also, seems it binds the worst after it goes into discreet shifting and line pressure clamps around 84 PSI.

I can't believe there isnt a table/setting that could help the TCM adapt. Only thing left is the Output Torque Shift Factor, ive halved that table with no noticeable difference, I also don't fully understand how to relate the oncoming shift pressure and offset pressures over elapsed shift time, to that table. Im not paying much attention to the other shifts being it is all put back to stock for testing.

Eric

[ns158sl]

Short update, it definitely seems to be related to when discrete shift is active. I am going to raise the TQ threshold a little bit to keep it out of High Torque Discrete, to save the trans for now until I can figure out a way to calibrate for no wave plate.

[TransGo Robert]

I don't know enough about tuning to know how to go around the problem that way. But removing wave plates, adding frictions or reducing clutch pack clearances always cause headaches on those. Not to mention it is not needed in the first place. If you ever have to go back in the unit, do yourself a favor and put all the clutch packs back to stock and install our 6L80-TOW&PRO kit in it and you will be amazed how great it will work.

[ns158sl]

I made all the clearances to spec and used GM methods with the special tools. Thats why I am having a hard believing there isnt a way to compensate for no "cushion" in the apply through the calibration.

I might be going that route. How would the tow and pro work with an added pressure Boost valve?

[TransGo Robert]

I made all the clearances to spec and used GM methods with the special tools. Thats why I am having a hard believing there isnt a way to compensate for no "cushion" in the apply through the calibration.

I might be going that route. How would the tow and pro work with an added pressure Boost valve?

There is a way to go around the problem that removing the wave causes, I just don't know how it is done in the tuning, that's not my strong point. No need to raise pressure on those they already crack drums and pistons, we actually limit it with our kit. The changes are done hydraulically in the unit moifying the rate at which the pressure increases as well as when it goes from regulated clutch pressure to full clutch pressure no matter what the computer does.

[hjtrbo]

Just thinking for your testing, perhaps keeping discrete enabled might help as its giving a repeatable pressure for you to judge other adjustments against. Saying that it gets worse in that mode, maybe the pressure for that threshold zone might need to come down a bit, which raises another question

With your torque tables, do you know how the numbers were generated?
I.e.
Matched up the rear wheel gear ratio corrected torque to engine torque PID or
Matched up the rear wheel gear ratio corrected torque plus drive line losses to engine torque PID

[hjtrbo]

There is a way to go around the problem that removing the wave causes, I just don't know how it is done in the tuning.

What is the gist of what needs to happen? Might be able to work it out between us.

[ns158sl]

I used the dynos calculated engine torque connected to the pro link. I'm not positive how accurate it is, but I figured it's closer than guessing lol. The little information I do have is it does factor in flywheel inertia, roller inertia, trans gear ratio, drivetrain ratio, drivetrain losses.

It seems discrete is for the adaptives to learn, but for some reason when it goes into High Torque discrete, it never "learns" correctly at 82 psi line pressure.

[TransGo Robert]

What is the gist of what needs to happen? Might be able to work it out between us.

The command for PCS 2 needs to change so that the 3-5 clutch it controls does not start to apply so quickly. It is applying during the fill phase of the shift (see attached graphs showing the 4 phases of the command for an oncoming elements). This phase is only supposed to fill the hydraulic circuit for that clutch without applying it. But once you remove the wave that is normally absorbing this pulse to fill the circuit it manages to start applying the clutch, and since the 2-6 has not started to release yet, you get the bind. So if you look at the two screenshot I am attaching of the OP's log you can see the bind in the red circle I added and the fill phase command in the read box I adeed. One is zoomed out where it is easier to see the bind, the other one is zoomed in more so that you can see better how the computer is controlling each phases of that shift. So what you need to change is how high the solenoid output pressure command is during the fill phase. I have no idea how it is done, but I know it can be done because the bind up when people remove waves or reduce clutch pack clearances is a very common issue, and many times the transmission techs will say "my tuner fixed it".
Shift Phases.png
Bind 2-3.png
Bind 2-3 (1).png

[mikez71]

Curious what vehicle is this out of?
I don't understand the details, but have noticed these differences on the tuning side.

'15+ have no adder modifiers. And 1-2 and 5-6 volume presets halved, extra disc (6l90?) or someother change?
'15+ desired torque ouput 1-2 has positive and negative numbers, '12 model only had negative numbers
'18+ desired torque ouput factor tables zero'd for 1-2 and 2-3 shift.
Also the '18 tune has 2-3 offgoing pressure reduced a little..

I tend to like the 18+ settings simply because less tables are used!

If anyone has basic explanation of desired output torque factor, adder modifier map, and transition times... I'm all ears.

[ns158sl]

This is exactly what I seen. There is a guy from SIU that put in pressure taps and recorded everything happening. My problem is I can't find a way to reduce the fill phase through HPT. There are presets, but the adapts just take over that after driving.

[TransGo Robert]

This is exactly what I seen. There is a guy from SIU that put in pressure taps and recorded everything happening. My problem is I can't find a way to reduce the fill phase through HPT. There are presets, but the adapts just take over that after driving.

Yea Sean Boyle does a great job as usual explaining each phases of the shift and it was quite interesting to follow along as he was doing all the testing. I will let others that know about tuning give you advice, but I can't help but wonder if you could not simply solve your issue by disabling the adapts?

[ns158sl]

Curious what vehicle is this out of?

2012 Yukon

[hjtrbo]

There is a few knobs to be turned. It appears from all my internet searching the fix is not public. I have a significant dis-taste for people hiding information, just small cock bull shit if you ask me.

ns158sl I have no idea to be frank, but here is a screenshot anyway.

My thought process is;

• Reset the adapts. You'll only get a small window to where it's adapted away from the initial settings. I imagine after every change whilst testing you would reset the adapts again.
• Clamp the fill volumes for 2-3. Raise or lower to find the 'kiss' point. To high it'll bind, to low it'll flare.
• Pressure presets, thinking leave alone whilst you're adjusting volume. We must only turn 1 knob at a time. Pressure and time would be proportional to volume I think.
• Discrete shift torque. I'd be inclined to leave that alone as its giving you consistent shift pressure to evaluate the changes
• Ideally a load bearing dyno so trans torque can be kept constant for back to back comparisons.

I have no idea but goodness me, ns158sl if you're willing, there will be some good data to look at.

[GHuggins]

Why not lower the adapts and fills for the clutch having problems? Don't know if these are anywhere near right, so ease up to what you're testing for throttle wise to make sure it's not going to slip. Goal is to apply enough to bleed air without applying the clutch. I'm not a fan of removing the waves. They're there for more than just cushioning the shift. They're also used to separate the clutch for the next application. You can wind up causing problems with them gone from a clutch not disengaging quick enough just as easily with them being there for other reasons only things are easier to set up with them there.

[GHuggins]

There is a few knobs to be turned. It appears from all my internet searching the fix is not public. I have a significant dis-taste for people hiding information, just small cock bull shit if you ask me.

ns158sl I have no idea to be frank, but here is a screenshot anyway.

My thought process is;

• Reset the adapts. You'll only get a small window to where it's adapted away from the initial settings. I imagine after every change whilst testing you would reset the adapts again.
• Clamp the fill volumes for 2-3. Raise or lower to find the 'kiss' point. To high it'll bind, to low it'll flare.
• Pressure presets, thinking leave alone whilst you're adjusting volume. We must only turn 1 knob at a time. Pressure and time would be proportional to volume I think.
• Discrete shift torque. I'd be inclined to leave that alone as its giving you consistent shift pressure to evaluate the changes
• Ideally a load bearing dyno so trans torque can be kept constant for back to back comparisons.

I have no idea but goodness me, ns158sl if you're willing, there will be some good data to look at.

I was apparently making changes when you posted this Don't forget the pressure presets too... Again, I don't know if what I posted is near right. Every one of these acts different depending on the build.

[ns158sl]

Well i appreciate all the info. I can get it on the Dyno here in a few days so I might as well wait until then to make changes.

[hjtrbo]

ns158sl are you all over discrete shift torque? Happy to go over it if needed.

[ns158sl]

Why not lower the adapts and fills for the clutch having problems?

because that is just presets. The algorithm is going to learn what "it" wants. I have tried that and found the outcome the same.\

all over discrete shift torque?

Not sure. I have a bit to clean up yet, but I will put this thing back on the dyno for testing.

[hjtrbo]

Not sure. I have a bit to clean up yet, but I will put this thing back on the dyno for testing.

Was meaning if you needed an explanation on how it worked.