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Thread: New A6 Transmission parameters walkthrough

  1. #21
    i'll try to put together something over the coming weeks, but ask away - can't guarantee you will understand the answer though...
    I count sheep in hex...

  2. #22
    Tuner carneb's Avatar
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    Just a few questions.

    - Shift time transition, initial and final. The units for the cells are %, but % of what? Is the initial and final related to the time of the oncoming clutch, and the offgoing clutch?

    - Desired output torque. Is this controlling torque output from the engine (torque management) or is it torque transmitted from the input of the trans to the output? What do the row headings represent (0,0.125,.25...)? Is this percentage of time through the shift? The cells have no units. What are they?

    - Base shift pressure. Lots of tables have pressures over 1000kPa but the max pressure setting is 758kPa. What's the point?

    - Discrete shift torque. Haven't got a clue about this one. Seems to only be used on 1-2 and 2-3 shifts on the tunes I've looked at.

    - Oncoming and offgoing pressure preset. What do the row headings represent (0,1,2)?

    That will do for now The rest of the stuff 'seems' straight forward, but knowing what to change won't be.
    Last edited by carneb; 06-11-2008 at 01:11 AM.
    VE Calais V 6.0L L98 V8 6L80E

  3. #23
    This is what i make of it...

    The trans mostly uses a inertia torque based "profile" to control the shift, ie. it manages the engine torque to try and achieve the desired torque profile during the shift progression (time) and then manages the shift pressure to achieve the desired shift time. You need to remember that the trans has individual pressure solenoids on each clutch *and* a main pressure solenoid (aka force motor on older 4l60e trans).

    Starting with the easy one, the main or "Base" pressure is controlled by the main pressure solenoid. This works quite simple compared to the rest of the trans. There are 3 possible pressure patterns X, Y & Z. Each shift mode or type can be set to a particular base pattern defined in the Pressure Pattern Select section. Note that another change we made in this new release was to remove Cruise and Performance tables and replace them with Pattern A Shift and Pattern B shift (note this is a shift pattern *NOT* a pressure pattern and you can see what A & B relate to under the Shift Pattern Type.

    So the base pressure X, Y or Z is selected by the current shift mode and then the actual pressure for the shift is controlled by the base tables themselves for each shift. The main solenoid feeds the line pressure to the whole trans, including the clutch pressure solenoids. So you can think of this like your water mains pressure at your house. Raising or lowering your mains pressure does have an effect on how fast the water comes out your kitchen tap but not as big effect as turning the kitchen tap itself (the clutch pressure solenoids).

    Sometime GM uses "Discrete Shift Torque" instead of the actual shift torque, to give a less modulated (more constant) base pressure to the main line so that the clutch solenoids and pressure learning is more stable. What this does is define a low, mid and high range for torque and then set the torque number to a fixed value while torque is in the range, so then the pressure lookup in the base table is also constant.

    Okay so that's the base pressure... now onto the torque based stuff...

    The inertia torque is "factored" into a number between 1 and 9 which is then used later to modify the base shift time and other things. From what i can tell this is the primary thing calibrators use to control the shift "feel" once the main things are calibrated. You'll notice in the Shift Intertia Factor Profile tables, higher numbers are used at higher torque and RPM. Further on in the Shift Time Inertia Adders you'll notice that these higher numbers equate to smaller additions to the shift times (ie. shorter shift times, which equate to higher pressures and firmer shifts). The basic idea here is that the shift is all about managing the rotating intertia change in a certain time between the shafts and clutches as some speed up and slow down during various shifts.

    You will also notice that the shift times have two primary type "Normal" and "Special". This is selected by the Pressure Pattern Mode options ie. each of pattern X, Y & Z can be set to shift times Normal or Special.

    So you end up with a base shift time + some adders based on intertia torque and other stuff. This shift time is then used to setup the desired torque profile.

    The Shift Time Transition Initial controls when during the shift completion (% of shift time) the torque based model starts, then the Shift Time Transition Final controls when it ends - kinda the ramp in time and ramp out time as far as i can tell. Probably used as a way to wait for things to stabilise enough for the torque based model to be accurate, then ramp out once the shift is basically complete. Again, at higher torque and RPM the numbers get smaller.

    The desired output torque factors and multipliers control the torque profile itself and experimentation will be required to see exactly what these do, from what i make of it they control the shape of the torque profile as the shift complete's. ie. more torque in the initial shift and less later or the other way around depending on probably a million other things that maybe one person in GM fully understands!

    If you have understood anything so far you will realize at this point there are two ways to change the shift feel. Either go in an change the shift times themselves *or* mod the inertia factor profile so that the smaller adders are selected at lower torque/RPM. If you aren't egtting good shifts at full throttle then you probably want to change the shift times themselves to be shorter, since you are already at Profile Factor = 9 in most cases. If you just want firmer part thorttle shifts and are happy with everything else then maybe just increase the Profile factor from say 3 to 4 or 5 in the mid range torque/RPM areas.

    Hopefully by now you've worked out that if shift time controls all this then the pressures must learn to achieve the shift times required, and yes they do. Individual pressure solenoids are controlled by the torque profile and shift time learning, they are adaptive. This trans is *very* good at learning in most cases and this is why you don't hear of many 6L80e trans breaking due to low-mid boost FI applications, unlike back in the 4L60e days which only in some cals had adaptive learning enabled (which was very primitive).

    So, you've got the various pattern selects, pressure mode, the base pressure patterns (main solenoid), base desired shift time + modifiers (mostly controlled by calibrated inertia factor 1-9), torque controlled pressure solenoids and adaptive learning to achieve the shift times. Easy huh?!?!?

    Please take small steps. You can see now why we were reluctant to add this stuff to the editor as it really does require a detailed knowledge of the theory behind it all and also the operation of the trans itself to fully comprehend what is happening. Even then i doubt there is anyone at GM who knows everything about how this sucker works! (btw, if that person does exist and reads this maybe they can post

    Bill, might be a good idea to sticky this someplace.

    Chris...
    I count sheep in hex...

  4. #24
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    Very helpful.

    The last wright up from Chris was extremely helpful. Thanks, Thanks, and Thanks again.

  5. #25
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    Okay, here's what could be a tough question:

    After blowing up the A6 transmission in my 2007 Corvette last week, I'm admittedly concerned about doing it a second time if I continue to race.

    Are there any specific parameters in this new version that I can adjust to help prevent that from happening again? I know that leaving TM enabled during upshifts will probably help keep the transmission safe, but I'm worried about how much of an effect it'll have on my ET.

    Any thoughts or suggestions?

  6. #26
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    No parameter is going to majically save your transmission in any vehicle, that is one of those "you gotta pay to play" scenerios where if you're going to race your vehicle you are going to break parts.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  7. #27
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    Quote Originally Posted by Bill@HPTuners
    No parameter is going to majically save your transmission in any vehicle, that is one of those "you gotta pay to play" scenerios where if you're going to race your vehicle you are going to break parts.
    That's a bummer.

    I've only got 27K miles on the car and only 417 HP to the rear wheels so racing the car may not have been the sole cause of why it failed since other people race with a lot more horsepower.

  8. #28
    you've got to remember we are at the very beginning of aftermarket knowledge on this trans from both a mechanical/electrical side of things from trans builders and also the tuning side. This time is even worse becuase it has to be the most complicated thing to tune i've ever seen, that's for sure.

    Until some serious racers and shops get out and start breaking this trans over and over again one of two things will happen, a) they will find the weaknesses or b) they will give up and resort back to t350/t400's just like they did with the 4Lxx trans.

    If the shifts are sloppy then yeah you gotta wonder why, becuase you know something will probably break eventually. But it will be an experienced guy who even notices that, for me it's damn hard to even tell when the first few shifts are even happening on the A6... lol
    I count sheep in hex...

  9. #29
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    Quote Originally Posted by BBA
    So, does anyone know what it would take to convert the external TCM wiring to the internal type? Say, wiring in a 6L80/90 in place of a 4L70? I'm thinking a wrecked escalade should be a good source for the trannies...might even be able to find an AWD compatible 6L90 trans for my TBSS...that would be the shiznit. Maybe the shifter from the escalade would be needed too...do they have console shifters?
    The TCM pretty well only has power/ground and the GMLAN connected to it. The exceptions are Stop Lamp input (TCC cancel), Accessory power line & Park/Nuetral output.

    Anyone contemplating changing to a 6L80/90 needs to take into account that they will most likely need a T43 compatible ECM.
    Last edited by LSX378; 02-20-2009 at 05:19 AM.

  10. #30
    Tuner carneb's Avatar
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    Anyone have any technical info on the 6l80? This is the best I've found http://www.cadillacfaq.com/stsfaq/ts...-07-30-023.pdf
    VE Calais V 6.0L L98 V8 6L80E

  11. #31
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    Quote Originally Posted by Bill@HPTuners
    Most of you know our engineers have been hard at work adding new features lately to all of our platforms, one project that is finally finished is adding ~460 new transmission parameters for the A6 which includes but is not limited to the Corvette, G8 & many trucks/suv's. Now with over 1000 editable tables & parameters for most calibrations we are confident we have one of if not thee most complete package for tuning these vehicles.

    In light of this for those who would like a glimpse of the added goodness I present to you the A6 parameter walk through which will show you all of the current & newly added parameters for the TCM.

    A6 Walkthrough
    Very impressive achievement.

  12. #32
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    Thank You! :bowdown:
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  13. #33
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    I'm curious to which vehicle you were looking at when thay screen shot was taken. I looked at an 08 G8 GT, an 05 C6 Corvette, and an 06 Corvette VCM file, but the trans section was not anywhere near that extensive.

    The verison of HPT I have is 2.22.3035 (just downloaded it from the cust support page).

    This is not all that importaint to me right now since I only have a GTP to play with, but I plan on a G8 next year (when the GXP comes out) and want to get familier with this as much as possible.

    Thanks guys, you are the best - hands down!!!!!!!
    -Eddie

    1998 GTP - 3.4 [3.2] [3.0] MPS - custom CAI - F.1 Ram Air hood - XP Cam - Ported Heads - 1.84/1.60 Si valves - 1.6 HS Roller Rockers - 72mm Ported TB - LQ4 MAF - 42.5# Lucas Injectors - Pacesetters
    1/4 PB - 13.025 @ 106.81 MPH w/ 2.069 60'
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  14. #34
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    G8 & 06 corvette would have those parameters available. The screenshot was from a denali I believe but the parameters are all the same. 05' Vettes use an A4 transmission.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  15. #35
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    Wierd

    I'll have to look at some others than, I guess I missed it. Here is what I see for a G8 GT in the repository. The 2008 Sierra, Corvette, and 2007 Silverado are all the same.
    -Eddie

    1998 GTP - 3.4 [3.2] [3.0] MPS - custom CAI - F.1 Ram Air hood - XP Cam - Ported Heads - 1.84/1.60 Si valves - 1.6 HS Roller Rockers - 72mm Ported TB - LQ4 MAF - 42.5# Lucas Injectors - Pacesetters
    1/4 PB - 13.025 @ 106.81 MPH w/ 2.069 60'
    2021 Chevrolet Colorado 2.8 Baby Duramax

  16. #36
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    Quote Originally Posted by Eddie-98GTP
    I'll have to look at some others than, I guess I missed it. Here is what I see for a G8 GT in the repository. The 2008 Sierra, Corvette, and 2007 Silverado are all the same.
    Then you are running a version thats several weeks old or older.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  17. #37
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    Huh, I just downloaded it yesterday...

    Maybe I need to check again, I may have installed the one I downloded a few weeks ago.
    -Eddie

    1998 GTP - 3.4 [3.2] [3.0] MPS - custom CAI - F.1 Ram Air hood - XP Cam - Ported Heads - 1.84/1.60 Si valves - 1.6 HS Roller Rockers - 72mm Ported TB - LQ4 MAF - 42.5# Lucas Injectors - Pacesetters
    1/4 PB - 13.025 @ 106.81 MPH w/ 2.069 60'
    2021 Chevrolet Colorado 2.8 Baby Duramax

  18. #38
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    Or you may have downloaded & install a cashed version or something(I've seen this happen). The newest version is 2.22.3079.28837 which was built ~8 days ago.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  19. #39
    Chris,

    I played a fair amount with a C6 A6. 1 thing I would like to know is if by chance there is 1 more table that can/may be available. Right now it seems that the "Base CT downshift - select" table relates to the Tap up/down shifts.
    It really makes a nice impact on the down shift speeds when tapped down. But, I do not see its upshift counter part and hoping its in the background somewhere. The down shifts are now so much faster than the upshifts and I cant seem to find the knob to balance it .

  20. #40
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    A quick question about the Oncoming and Offgoing Pressure preset tables. What do the row headings mean (0,1,2)? Are they the start, middle, and end of shift, are they low, medium, and high input torque, or something else? I've experimented with most of the other parameters to see what they do but haven't been game to play with these ones.
    VE Calais V 6.0L L98 V8 6L80E