Shift flare

newdude · April 27, 2017

This.... Exactly!

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I'll do ya one better to my other post:

#PIP5429: 2-3 Upshift Slip or Flare

Some customers may comment on a 2-3 upshift slip or flare.

This condition is a NORMAL characteristic of the transmission, it will not cause durability concerns and no repair attempts should be made.

At this time this flare condition has been recognized in two different driving conditions:

During the first 2-3 upshift after the vehicle has been sitting, engine off for several hours. This condition may be caused by air that is trapped in the 3-5-R clutch assembly.
When the first 2-3 upshift is made this trapped air is purged and the following 2-3 shifts will be normal with no flare.

When diagnosing this condition a garage shift into reverse before drive will purge this air and prevent the 2-3 flare from occurring. This condition is a NORMAL characteristic of the transmission, it will not cause durability concerns and no repair attempts should be made.

When transmission ATF temperature is at or below 85 degrees F (30 degrees C). This 2-3 upshift flare can occur until the ATF temperature warms. If the 2-3 flare is determined to be ATF temperature sensitive use a Tech 2 to make note of the throttle position when the flare occurs. Drive the vehicle to get ATF temperature to at least 104 degrees F (40 degrees C) and then make several 2-3 shifts at the throttle position determined to be the most sensitive to the 2-3 flare. This will allow the transmission adapts to tailor the shifts and may help to eliminate the cold 2-3 flare. This condition is a NORMAL characteristic of the transmission, it will not cause durability concerns and no repair attempts should be made.

This covers the 6L50, 80 and 90 from 2006-2017, and all vehicles that use them.

rocnrol · April 27, 2017

That's awesome information! Thanks!!

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sdeeter19555 · April 29, 2017

I just had a thought on shift flair...maybe it's not all in the trans?

Now, I'm not into the weeds on these newer trucks, but I do know they pull the power back just for a split second when the trans shifts and locks up, for longevity. Could the trans be doing its thing and the rest of the system not pulling the power off, and that's what causes the flair?

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SMiller · May 12, 2017

I spent hours having the 6L90E in my truck tuned via EFI live, even running tons of line pressure, no torque management, speeding the shifts up, doing everything my tuner could and guess what, still has a insane 2-3 shift flares, only does it once every week or so, not every day or every shift, just a certain throttle position at a certain time, weird drives me crazy, at least we can say we tried.

For those that have a tuned 6.0/6L90E you have no idea what you are missing, my truck drives 110% different, upshifts when you want, downshifts when you want, nice torque converter lockup, nice firm shifts, no dead pedal, no speed limiter, better mileage, nothing but love!

rocnrol · May 12, 2017

I spent hours having the 6L90E in my truck tuned via EFI live, even running tons of line pressure, no torque management, speeding the shifts up, doing everything my tuner could and guess what, still has a insane 2-3 shift flares, only does it once every week or so, not every day or every shift, just a certain throttle position at a certain time, weird drives me crazy, at least we can say we tried.

For those that have a tuned 6.0/6L90E you have no idea what you are missing, my truck drives 110% different, upshifts when you want, downshifts when you want, nice torque converter lockup, nice firm shifts, no dead pedal, no speed limiter, better mileage, nothing but love!

You're killing me with this

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deesherman · May 18, 2017

My 2009 2500HD silverado 4x4 was rebuilt by the dealer and that did not fix the up shift.

Putting the transmission in reverse for 1 minute in the mornings will bleed out the air and reduce the slip.

alkaspeltzar · April 25, 2018

i have a 2014 that my dealer says has this issue, provided me bulletin PIP5429: 2-3 Upshift Slip or Flare

But does flare mean HARSH SHIFT?

My truck has a harsh 2-3 shift when cold until tranny temp is 100F. Then it is smooth. Like a manual transmission dropping clutch.

Any opinions or help wanted. I want to fix truck before I loose my warranty. Thank you

sdeeter19555 · April 25, 2018

Mine only occasionally flares, but it is not a harsh shift.

2012 2500hd 6.0l CCSB 4wd

SierraHD17 · April 26, 2018

My 09 did it bad... stupid pos would rev up and bang the limiter if you had your foot into it a bit. That same 09 locked the back tires up at 30 mph with a part throttle tip in and it banging up and down a couple gears lol. My 17 sitting at 20000 miles has yet to do it and its been tuned via hp since I bought it new... luck of the draw lol. I'm not complaining haha.

bobsiding · April 26, 2018

my 17 hd does it when in the mountains. I wish I could tune it but only have 800 miles on it. I hate the way it shifts.had a stick before and wish manual mode was a true manual mode. not just something they dreamed up. I hate when it pulls hard and downshifts then upshifts right away like it cant make up its mind or searches for the right gear. when I had a stick didn't have any trouble in the mountain passes as I controlled it .I didnt have to worry about gms trans tuning. bring back the stick. last truck with a stick I had 175000 miles on the clutch. pressure plate let go. clutch was still good. had a snowplow and an 18 ft tool trailer and a dump trailer. lets see an auto trans do that. and I changed the clutch myself. lets see you do that with an auto trans