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Thread: 8L90E I want a crisp shift. Seems to drag between gears

  1. #21
    Quote Originally Posted by lucas287 View Post
    Curious what your TCC suggestions have to do with directly making the shifts crisp?

    I never had luck with the inertia tables. I left all the pressures alone too. I've only changed the shift timing tables, up and downshift, modifying the areas that feel slow by about 10% quicker at a time. The big results are in the Shift Torque Factor Adder Modifier tables.

    Here's how I have mine set up:

    Attachment 104118

    Attachment 104119
    I really like the idea of the tq adder thing. Didnt even know that was a thing.

    Quote Originally Posted by Joshinator99 View Post
    Your max pressure is half of where it should be. TCC Apply Pressure Ramp is way too conservative. I'd suggest TCC Desired Slip to zero across the board too. Just my humble opinion, of course.
    Are you referring to Max Line pressure 5100? 2000KPA?

    Zeroed Desired slip across the board.

    What should the ramp rate look like 15235?

    TCC Lockup is all part of the equation. I like a firm lockup.

    Quote Originally Posted by lucas287 View Post
    ^ These changes alone will bark the tires on the 1-2, 2-3 shift at WOT. That's crisp enough for me. At light throttle it feels stock but quicker.

    I like to monitor the TQ MGMT spark at higher throttle inputs and try to keep the timing advance slightly positive.
    Modifying the minimum spark table on the engine side can help with that part.

    I have taken the few shorter desired shift times you have in your tune and added them to mine. Can re-post if you were interested.

    Quote Originally Posted by lucas287 View Post
    Feels normal, nothing weird or clunky about it. In fact, I haven't touched anything on the downshift side. Upon looking at my latest tune a bit more, I actually left the downshift times completely alone. I feel like they are intentionally slow on the multiple gear downshifts to prevent damage. Plus, if I'm romping around I don't leave it in D. I'll limit it to 5th or 6th to prevent having to go from 8th to 3rd/4th (the shifts that take FOREVER)

    You can get more downshift response/aggressiveness by modifying Shift Scheduling --> Part Throttle Shift --> Normal: Downshift.
    See I like that downshift bump. Did you change your desired shift times for the down shifts? If so that's when mine started to show up.

    Also I'm working on a tuning guide for these transmissions. Ill convert the first post to a guide. Input welcome.

    8L90E T87A Controller.doc
    Last edited by HellKnightHicks; 10-18-2020 at 01:22 PM.

  2. #22
    I honestly feel that the Adder tables arent workin on my Controller. The shifts are lighter than ever after Removing the modifications I had on the Torque factor. I even set the adder tables to add -.45

  3. #23
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    Quote Originally Posted by HellKnightHicks View Post
    I honestly feel that the Adder tables arent workin on my Controller. The shifts are lighter than ever after Removing the modifications I had on the Torque factor. I even set the adder tables to add -.45
    Interesting! Try this as a test,...

    Trans --> Torque Management --> Torque Reduction --> Upshift (TCM 421) : change this to disable.

    Then go for a drive and tell me how it feels. It should be very violent. Like anything past 50% should get your attention. That's why I dialed in my Shift Torque Factor and Adder Modifier. It was way too violent with it removed, so the adder modifier will only remove how much you tell it to. Make sure you have it set up like this for the formula to work correctly (adder modifier is however much reduction you want)

    STF.JPG
    STF 2.JPG
    Adder Modifier.JPG

  4. #24
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    Quote Originally Posted by HellKnightHicks View Post
    I honestly feel that the Adder tables arent workin on my Controller. The shifts are lighter than ever after Removing the modifications I had on the Torque factor. I even set the adder tables to add -.45
    Just scrolled through your word doc and it seems like you understand everything I just explained about the adder modifier tables....so idk man! Vehicles are fickle, that's for certain.

  5. #25
    Quote Originally Posted by lucas287 View Post
    Just scrolled through your word doc and it seems like you understand everything I just explained about the adder modifier tables....so idk man! Vehicles are fickle, that's for certain.
    Yup. Might be something with my particular OS that doesnt want to use those tables. I had 40% tq management removed from 1-2 2-3 shifts and it was noticeably softer on both of those shifts when attempting to use the tq adder tables.

    There area some other odd things Ive run into while tuning this truck.


    I did take some of your shift timings that were lower than mine. Im afraid to go to low because ive heard reports of hung shifts or binding in the transmission between gears.

    Still if those tables work thats a great thing for those it does work for. I wander what the safe limits are for removing tq management. I know we need to keep some to protect the transmission but id like to know what peoples experiences are.

  6. #26
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    Quote Originally Posted by HellKnightHicks View Post
    Yup. Might be something with my particular OS that doesnt want to use those tables. I had 40% tq management removed from 1-2 2-3 shifts and it was noticeably softer on both of those shifts when attempting to use the tq adder tables.

    There area some other odd things Ive run into while tuning this truck.


    I did take some of your shift timings that were lower than mine. Im afraid to go to low because ive heard reports of hung shifts or binding in the transmission between gears.

    Still if those tables work thats a great thing for those it does work for. I wander what the safe limits are for removing tq management. I know we need to keep some to protect the transmission but id like to know what peoples experiences are.
    Some people on here just use that master disable switch for upshift tq mgmt I mentioned. Russ Kemp specifically. I tried it, but it was crazy violent. So, for me and my truck, it appears I need some tq mgmt. I think with a heavy truck it's more important than a light Camaro and even lighter Corvette.

    Side note, I've had zero issues with shift timing! Take a look at Pattern A (Tow/Haul) shift times and you'll see how low GM programmed some of the shift times. I did reduce downshift times too. I don't have a single table now that exceeds "1.0" second. It's a noticeable difference.

  7. #27
    I've been dropping the timings to the lowest I can find in the stock tables from multiple stock vehicles running that Transmission.

    1-2 is great 2-3 feels clunky... The rest feel great.

    Will post a completed guide once Im happy with the results.

  8. #28
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    Quote Originally Posted by JR2010 View Post
    Here is my current tune. All stock but with AFM/DOD disabled, MAF x 1.05.
    why the maf x1.05?
    honest ?

  9. #29
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    Just playing with the airflow to see if would make a difference. It really did not do anything with a stock rig. So went back to stock maf, put the transmission back to stock, reset the adapts in the transmission and let it do its thing.

    I made some minor changes in the VVT hi baro table and increased timing by a few degrees down low. Feels real good right now, have the occasional flare in 2-3 and 3-4 but not all the time. I still get some bucking when coming off the highway at higher rpms, it seems like its staying in a higher gear then dropping down, haven't figured that one out yet.

    With these changes my mileage has improved and as much as i drive that's a good thing.
    2016 Sierra Denali 5.3L - All stock but the air filter & GMPP Borla exhaust

  10. #30
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    I don't believe we have near the things we need for proper control of this transmission, the 6L80s I've seen and Allisons all were the same way, you can put whatever you want for shift timing in the tables. Sometimes it will start to follow what you put in there after a relearn, sometimes it will completely ignore it, and the after a while if it did work, it will "learn" back to the same bad/sloppy/clunky/pushy/harsh shift feel.

  11. #31
    Quote Originally Posted by cmitchell17 View Post
    I don't believe we have near the things we need for proper control of this transmission, the 6L80s I've seen and Allisons all were the same way, you can put whatever you want for shift timing in the tables. Sometimes it will start to follow what you put in there after a relearn, sometimes it will completely ignore it, and the after a while if it did work, it will "learn" back to the same bad/sloppy/clunky/pushy/harsh shift feel.
    What really seemed to help was the pressure offset. I can tell a difference and it seems to stick. Especially tow haul mode.

    Most of my timings are now down to .240 and then ramps up as power increases.


    I do feel that the shifts aren't quick though. There's still some dip in the power during as shift. The minimum spark table helped with that some.

    Maybe im just wanting what i used to feel in the old 4l60e's instant shift and these just dont shift that way.

  12. #32
    [QUOTE=JR2010;628731 Also, soak the bolt in Mouse Milk or something to release the rust and not strip it out. I spent more time getting that off than doing the rest of the system.[/QUOTE]

    where do you get mouse milk? don't tell me i have to squeeze it out of a rat's titty

  13. #33
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    One trick that I use is in the Coefficients table in the ECU. It's essentially a requirement for the A10 transmissions since there is less control. Basically you are increasing the torque value the ECU reports to the TCM and it will improve the shifting a bit.
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  14. #34
    Quote Originally Posted by TriPinTaZ View Post
    One trick that I use is in the Coefficients table in the ECU. It's essentially a requirement for the A10 transmissions since there is less control. Basically you are increasing the torque value the ECU reports to the TCM and it will improve the shifting a bit.
    What table specifically are you talking about?

    Thanks

  15. #35
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    I think he is talking about the virtual torque coefficients, I guess you would increase the virtual torque where you wanted firmer shifts. That sounds like it could mess up some other stuff you don't want to mess up though? I would think its less of a workaround by raising minimum timing advance? but I'm not sure i've never tried it, I always try to keep virtual torque stock.

  16. #36
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    Quote Originally Posted by HellKnightHicks View Post
    What table specifically are you talking about?

    Thanks
    Quote Originally Posted by cmitchell17 View Post
    I think he is talking about the virtual torque coefficients, I guess you would increase the virtual torque where you wanted firmer shifts. That sounds like it could mess up some other stuff you don't want to mess up though? I would think its less of a workaround by raising minimum timing advance? but I'm not sure i've never tried it, I always try to keep virtual torque stock.

    Yes I am talking about the Virtual Torque Coefficients. Don't go crazy here and only adjust the WOT EQ Ratio area. What is the torque control method set to in the TCM? Have you tried changing it to "Immediate"? This isn't recommended for high power cars though. Minimum spark tables will reduce the torque pulled on shift but can also make decel drive-ability feel weird.
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  17. #37
    Quote Originally Posted by TriPinTaZ View Post
    Yes I am talking about the Virtual Torque Coefficients. Don't go crazy here and only adjust the WOT EQ Ratio area. What is the torque control method set to in the TCM? Have you tried changing it to "Immediate"? This isn't recommended for high power cars though. Minimum spark tables will reduce the torque pulled on shift but can also make decel drive-ability feel weird.
    Yea I've not changed the shift to immediate. I should be putting out a good amount more than stock.

    Virtual TQ isn't something I've messed with. But likely needs to be adjusted.

    Ill probably get a dyno tune when I swap the CAM and see what they do. Where these A10(? i think) Trans controllers are locked and you cant read from them. I dont know what whipple did in the there tune.

    Ive made a lot of progress with it but i still really hate the shift points on the regular drive mode. Havent had much luck getting blue cats to work either.

  18. #38
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    I really hate how we still have to work around things on the T87 and have to adjust minimum spark to tune torque reduction on upshifts.

  19. #39
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    Quote Originally Posted by cmitchell17 View Post
    I really hate how we still have to work around things on the T87 and have to adjust minimum spark to tune torque reduction on upshifts.
    You will considerably shorten the life of the clutch packs in the transmission if you don't let it pull timing on shift. The best bet is to use Immediate setting in torque recovery. This will pull timing on shifting and then immediately return the timing once the shift completes rather than ramping it back in softly. It works great for bolt on cars but when you start getting into 800+ rwhp on the 10 Speeds it can cause the 4-5 gear to slip the clutches and the trans will flair when trying to shift.
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  20. #40
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    Quote Originally Posted by TriPinTaZ View Post
    You will considerably shorten the life of the clutch packs in the transmission if you don't let it pull timing on shift.
    Some people like Russ K just recommend turning off upshift TQ mgmt entirely. I'm guessing recommendations like that are for all out performance and don't have longevity in mind?