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Thread: unusually hard 1-2 shift

  1. #1
    Join Date
    May 2005
    Posts
    23
    Lately my 1-2 shift is exceptionally harder than normal. All the other shifts are like usual, but unless I let off the gas for the 1-2, it practically bangs the shift. It's just a stocker 4L60E with nelson's tune.

    Any ideas?

    It's almost like its doing the super firm shift for WOT but it does it everytime with even the slightest bit of gas.

  2. #2
    Join Date
    Nov 2003
    Location
    Denton Texas
    Posts
    20,540
    Did you have Allen remove torque management? If your TPS is bad you will get the same effect, 1-2 shifts will bang hard as hell.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  3. #3
    Join Date
    May 2005
    Posts
    23
    ^^ No, I just had him do "the reccomended ammount"

    The tune's been in the truck for about 9 months now, this is the first I've ever had this happen.

  4. #4
    Join Date
    Mar 2003
    Location
    San Marcos Texas
    Posts
    4,393
    Do you have any SES codes? Tranny codes will cause the PCM to go to full pressure and bang the shifts.
    2006 Superior Blue Trailblazer SS AWD, Stock as a rock

    Sold: 2002 GMC Sportside Denali front end with a 2002 LS1, FLT level 5, Yank 2600, Trick Turbo, T76, Nelson intercooler, 60LB injectors, Warbro fuel pump, Eaton locker, Magnaflow, 3.42, Nelson Performance Tuning (speed density).

    Sold: 1981 GMC LB RC 1500 2002 4.8L 4L60E 12 bolt 3.73 Richmond Lock Right AC PS Nelson Performance tuning

  5. #5
    Join Date
    Dec 2004
    Location
    Andrews, NC
    Posts
    204
    Originally posted by GMCwantsLS1@Dec 8 2005, 06:22 AM
    Do you have any SES codes? Tranny codes will cause the PCM to go to full pressure and bang the shifts.
    Your 1-2 accumalator may be bad or sticking. Did I spell that right?
    2002 GMC Seirra scsb, 5.7LS1, Twin 62-1 turbos, Compcam 222/218, 4l80e, and Hptuners

    2006 GTO Black/Red, 6.0 M6, 238/240 cam, SW LT, exhaust & bolt ons = 438rwhp411rwtq!

  6. #6
    Join Date
    May 2005
    Posts
    23
    The SES light hasn't come on.

    YellowSierra - that's what I was thinking but wasn't sure if it is possible. Or maybe a solenoid is bad. Need a tranny whiz like Hitman to say for sure.

  7. #7
    Join Date
    Jun 2005
    Location
    Morehead City, NC
    Posts
    32
    I had Allen remove every "ounce" of TM possible. Shifts are firm but I would not say they "bang". I've had Transgo shift kits in previous vehiclss and they were much firmer than this... I lived up north back then it required a lot of care to dry those modded turbohydros in the ice and snow on the 1-2 shift... especially the modded '74 454 shortbed 4x2 on L70x15 Positraction tires.
    '07 Trailblazer SS 1SS 2wd. Jet-Hot Kooks & cat'd Y, Mufflex catback, Taylor TV 50's, TuneTime-Westers, CAI, new e-fans/160 stat, pulleys, built 4L70 & Vig 2800, trans cooler. Window tint soon!
    David-Morehead City, NC
    ############################# http://i177.photobucket.com/albums/w...tb/TBSS4-1.jpg ##############################

  8. #8
    Join Date
    May 2005
    Posts
    23
    Thanks for the suggestions fellas. I finally had the time to drop the valve body and poke around. Sure enough a spring in the 2nd accumulator broke and that was causing the harsh shift. Finally put the shift kit in that had been collecting dust for almost a year only taking 8 hours of wtf'n around under there.

    The final result is exactly what I was hoping for. I put in the HD2 kit with NO washers, vette servo, sonnax 4th gear servo, servo release check valve, and aluminum accumulator pistons. I used the transgo sep plate and didn't touch the 1-2 feed hole, drilled the 2-3 to .130 and all others to .093.

    Shifts are crisp in all gears and the 1-2 is not overly harsh. In fact it banged harder with my broken spring setup

    Hope this helps anyone who encounters a similar problem or looking for a good shift kit setup.

    Happy Holidays

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