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Thread: Removing TM on a 6L80E - helpful, hurtful or hard to say? (the answers are inside)

  1. #1
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    Removing TM on a 6L80E - helpful, hurtful or hard to say? (the answers are inside)

    Consider this a Public Service Announcement if you will, but for those of you driving your 6L80-equipped car hard but still have at least some TM enabled you're actually hurting your transmission rather than protecting it. (I know this is likely to start a heated debate and/or big controversy so I'm more than open to any and all opposing viewpoints on the subject)

    Contrary to what most people believe, TM is there for the purpose of having the transmission shift smoothly, not to protect it. Under normal, part-throttle driving conditions it's fine if you leave some (or all) of it in but if you regularly run the car balls-out (i.e. at the dragstrip like I do about 300 times a year) you'll kill the trans much faster that way as compared to turning it all off.

    The reason being is that there are roughly 30 or so clutch disks in the 6L80 and TM actually introduces slippage in order to achieve the smoother shifting which works great around town but not so much at full throttle. To illustrate this using a manual transmission as an example, think about how long your clutch would last at the track if instead of shifting it hard and fast you slipped it into each gear.

    As for a more relevant example we can use my car - I'm running a built transmission from Century using the new Alto clutch disks and I've made 157 low 10 second passes on it since September 2010 and it's still shifting perfectly every time. Granted it is a built transmission with more durable clutches but the same rules also apply to stock transmissions.

    I set up a friend's 2007 Corvette (with almost 70K miles on it) around two years ago and despite making over 300 passes while running high 10's/low 11's (depending on the DA) it shifts perfectly 99% of the time and shows absolutely no signs of any problems whatsoever. For the 1% of the time where it has acted up it's always after he got a REALLY good launch. This sort of goes against the grain with respect to traction issues on the 6L80 as it's usually a case of the more traction the better.

    So there you have it, let the debate begin I guess.

    Christopher

  2. #2
    Advanced Tuner midevil1's Avatar
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    THERE IS NO DEBATE. You are 100% correct. I have been saying it for years. I have been beating on mine for 4 years now. 5800lbs AWD 420whp. Broke a yoke but thats it.....
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    Quote Originally Posted by midevil1 View Post
    THERE IS NO DEBATE. You are 100% correct. I have been saying it for years. I have been beating on mine for 4 years now. 5800lbs AWD 420whp. Broke a yoke but thats it.....
    One for the good guys, I like how this thread is starting...

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    No TM for my 08 vette!

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    This does make perfect sense....

    How do you smooth the shifts though...Pressure? Times?

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    Quote Originally Posted by Jordan927 View Post
    This does make perfect sense....

    How do you smooth the shifts though...Pressure? Times?
    Honestly I really don't know as my car is pretty much a dedicated track car now. I do drive it on the street and freeway but that's pretty much just to get me to and from the track.

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    Cool man...thanks.

    I'll play around a bit I guess...find a compromise somewhere.

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    Advanced Tuner Bluecat's Avatar
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    I'll be back when I have more time.... alot more time.

    I've got to travel out of town today to tune a cammed zr1 for another shop and need to be getting on the road. I'll be back with my two cents. Until then everyone google and try to learn about the differences between how a standard automatic changes gears vs a clutch to clutch automatic. That way I'll do more to help this topic be contructive than piss everyone off.

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    ok I see everyone keep saying I kept 50% or less of the torque managment. Now unless Im completly overlooking something, where are you removing only a percentage of the torque nannies? As well how do you reduce it in certain modes, such as drive, sport mode, or tap up/down? as well competitive modes.

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    Quote Originally Posted by Goofyguy View Post
    ok I see everyone keep saying I kept 50% or less of the torque managment. Now unless Im completly overlooking something, where are you removing only a percentage of the torque nannies? As well how do you reduce it in certain modes, such as drive, sport mode, or tap up/down? as well competitive modes.
    Not sure where (or if) it can be done based on different driving modes but for removing just a percentage of it across the board take a look at Transmission->Torque Management->Shift Torque Factor.

    If you have TM enabled in the Torque Reduction dropdowns (just above STF) then the values here dictate how much TM should be left in the car with 1.00 representing 100% and 0.00 meaning it's all taken out.

    I've only experimented with this briefly (so somebody please correct me if I'm wrong) but what I've found is that it's not perfectly linear. What this means is that if leaving TM fully enabled pulls (as an example) 24 degrees of timing when the car shifts, leaving 50% of it in won't necessarily correlate to seeing only 12 degrees of timing being pulled.

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    I was told to use the modifier tab at the bottom...torque multiplier...maybe

    You also use -1.00 to 0.00 This modifies the other tables you were talking about, but VS rpm...so you can have different amounts removed at different rpm's

    The TM works on an equation,
    This table makes the equation negative therefore removing a percentage of TM

    -1.00=-100%...taking away 100%of TM.

  12. #12
    Senior Tuner IDRIVEAG8GT's Avatar
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    Introduces slipping..... Where's the table that controls T/M override of line pressure? And T/M's main function is to slow down shift times and pulls lots of timing out of the engine so basically you have a half assed method of RPM Matching in your auto transmission. Basically GM needs to step it up and start build trannies that take abuse and don't need all this Management crap.
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    Advanced Tuner madvette08's Avatar
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    They need to use a DCT Transmission like in the BMW M3 or something like AMG 7-speed MCT Transmission. But only one can wish lol.

    Ian
    2008 Corvette A6 - Comp Cams 231/239 617/624 109 ICL 113 LSA, Patariot Extreme Dual Springs .660", Milled .30" Stock LS3 Heads, Mahle -4cc pistons, FTI 3600 Converter, 1 7/8 kooks cat-less 3 inch X-Pipe, air raid intake, ported TB, SLP Loudmouth I. 512hp/464tq

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  14. #14
    Senior Tuner IDRIVEAG8GT's Avatar
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    Quote Originally Posted by madvette08 View Post
    They need to use a DCT Transmission like in the BMW M3 or something like AMG 7-speed MCT Transmission. But only one can wish lol.

    Ian
    Yep. I want one of those seven speeds in my truck.
    Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.

    PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.

    Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
    618/618 motor
    906/862 spray

    Caterpillar 50 Forklift- Duramax swap

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    I guess i'll start being the bad guy since i don't really know , but guess, that having some TM can benefit the trans as to not having TM at all. yes the trans slips with TM, like it does in those Chevy trucks that are used for heavy duties and can go 200-300k miles without trans work.

    On the other side, we have subfloor with 1000 track passes and possibly how many trans rebuilds already ??? 3 -4 ? in maybe 20-30k miles ??

    Hey, i don't know how the clutches work inside this trans, but i'm all ears. i'm running about 50% TM at part thottle, and as the requested torque increases, i decrease the TM to be about 10-12% left AT WOT during the shift, (gear dependant, i have 40% in 1st gear during the WOT shift, 18% during the 2nd gear WOT shift, and 10% during the 3rd gear WOT shift) this way i'm not roasting the tires during a 1-2 shift while having the quickest shift i can on Continental DWS Tires.


    I use the shift torque factor per gear/shift torque factor adders per gear (only for gears 1 through 4, i have 100% TM for gears 5th and 6th), and the adder modifier.
    Per the formula

    Final Torque Factor (FTF) is calculated like this:

    FTF = {Shift Torque Factor + (Shift Torque Factor Adder * Shift Torque Factor Adder Mod)} * Torque Factor Cold

    I don't change the torque factor cold at all since it's not needed.
    I even have a little excel spreadheet to calculate TM%

    I have 33K miles, driven hard,(This a DD that sees the track 6-7 times a year, i don't even use DR's on this car) and my trans seems to be holding up pretty well, i don't have trans flares, the trans temp is actually a little bit lower than stock most of the times, so how am i putting more stress on my trans compared to you guys that run without TM at all??

    Again, without TM, my 1-2 shift can be a handful at anything past mid throttle, the shift is hard, and frankly, it feels like complete shit that way.
    Last edited by bluegoat06; 03-23-2011 at 08:39 PM.

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    Quote Originally Posted by bluegoat06 View Post
    I guess i'll start being the bad guy since i don't really know , but guess, that having some TM can benefit the trans as to not having TM at all. yes the trans slips with TM, like it does in those Chevy trucks that are used for heavy duties and can go 200-300k miles without trans work.

    On the other side, we have subfloor with 1000 track passes and possibly how many trans rebuilds already ??? 3 -4 ? in maybe 20-30k miles ??

    Hey, i don't know how the clutches work inside this trans, but i'm all ears. i'm running about 50% TM at part thottle, and as the requested torque increases, i decrease the TM to be about 10-12% left AT WOT during the shift, (gear dependant, i have 40% in 1st gear during the WOT shift, 18% during the 2nd gear WOT shift, and 10% during the 3rd gear WOT shift) this way i'm not roasting the tires during a 1-2 shift while having the quickest shift i can on Continental DWS Tires.


    I use the shift torque factor per gear/shift torque factor adders per gear (only for gears 1 through 4, i have 100% TM for gears 5th and 6th), and the adder modifier.
    Per the formula

    Final Torque Factor (FTF) is calculated like this:

    FTF = {Shift Torque Factor + (Shift Torque Factor Adder * Shift Torque Factor Adder Mod)} * Torque Factor Cold

    I don't change the torque factor cold at all since it's not needed.
    I even have a little excel spreadheet to calculate TM%

    I have 33K miles, driven hard,(This a DD that sees the track 6-7 times a year, i don't even use DR's on this car) and my trans seems to be holding up pretty well, i don't have trans flares, the trans temp is actually a little bit lower than stock most of the times, so how am i putting more stress on my trans compared to you guys that run without TM at all??

    Again, without TM, my 1-2 shift can be a handful at anything past mid throttle, the shift is hard, and frankly, it feels like complete shit that way.
    I'm basing my observations on a few different factors:

    1) The 157 passes on my current trans while making close to 600rwhp and having zero TM in the car
    2) My buddy who has a few hundred passes on his 70K stock transmission and zero TM and zero problems
    3) My LS2 setup, where I made hundreds of passes without TM.

    I didn't start blowing them up until I went past the 550rwhp mark.

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    So i guess the question is then for us who still have some TM left, how are we hurting the trans ?

    This is 2nd automatic performance vehicle i've had, the other was a 99 Z28 with the a4 trans. rest of the cars were stick shift. so base on observations as well, although hard to compare a T56 trans with a 6l80e trans, but i started hurting clucthes and transmissions when i started powershifting with only 400-430rwhp. during the powershift, engine timing was flat, like we would see when we remove TM. if i was hurting the car clutches and transmissions doing powershifts, how is that so desirable to do the same with those 80 clutches inside our transmissions when GM designed them with slip in mind ???

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    I have my TM turned off also. Its the best way to go.

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    TM aside...how do you guys set up your pressure tables.

    Also, shift speed tables...I heard setting them at like .1, .25, .35

    I am going to likely remove all my TM...but I don't want the shifts to be too harsh. I heard a lot of guys just bumping the pressure tables and shift speed tables up and using the Shift Torque Factor Adder Mod to adjust the shift feel.


    What do you guys recommend for a 5600lb truck.

    I'm not gonna be racing it, yet, but I would like it to jump and run when I drop the pedal.

  20. #20
    I agree. There is no reason for torque management unless you want a soft/smooth shift plain and simple. Torque management is not there to save the transmission as some may think, it is only there to lower the power at the time of the shift to allow for less shift pressure and therefore a smoother shift. I turn off torque management in 98% of the vehicles I tune and do not have issue's of transmission failures as a result of that. Transmission tuning must be performed properly in full scale to make it all work as well as upgrading the trans as needed. This includes the engine tuning being done right. If the engine tune is not done correctly then the estimated torque reading that the computer calculates will be incorrect and the transmission shift pressures will not be correct since they are based on calculated torque output. The 6L80E transmission calibration is most often done incorrectly since it is not being done by people who understand shift timing and shift pressures. Too many people are using the tune it themselves method with information that they are getting from others who don't know either. Tune the trans tables right, tune the v.e. tables right, tune the maf right, etc, and your trans will live just fine. If you're putting down more power than even tuning can help, you may need to do some valve body work or servo work for those transmissions that use them, but they will live.

    I rebuild transmissions and tune professionally for a living. I have the experience to prove this as well as years of testing. GM's transmissions are just fine. People who kill 4L60/65/70E's all the time for example are either people who beat the crap out of them, people who have shitty trans builders, or people with shitty tuning. The 6L80E's will run 600RWHP for quite a while with good tuning in completely stock form. Eventually they will fail since parts will wear out, that's just what happens. As the 6L80E grows some age it is only going to get better. Hell the good old 700R4 that had a hard time handling 200FWHP when it came out is taking 700RWHP in trucks with good builds and tuning in the form of built 4L70E's.