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Thread: Skip/lock out 1st gear on 8HP70 or 90?

  1. #1
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    Skip/lock out 1st gear on 8HP70 or 90?

    Has anyone ever successfully tuned to skip 1st on the 8HP70 or 90?

    I've got a truck with a 3.92 rear gear and a bunch of nitrous off the line, the chassis holds the power but the 1-2 shift kills it, I was wondering if anyone has figured a way to lock out 1st like the Ford 10r80 guys are doing for the big power builds.

  2. #2
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    Eco mode locks out first.
    Attached Images Attached Images

  3. #3
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    I do this on lots of pd blower cars.
    Just zero the 1-2 2-1 columns in whatever mode you want it to launch in 2nd.

  4. #4
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    Thanks guys, Eco mode isnt an option on the trucks but zeroing the columns in tow haul mode made it so that when i press tow haul it eliminates first. Actually pretty nice to be a ble to have it on a button. Seems to function correctly, will have to finish it up and get to a track to see if its making any difference in ET.

    Hemituna, did you ever have any issues with some of your PD cars not wanting to complete the 1-2 shift? thats the reasoning behing my desire for this, i had a ton of trouble with the 1-2 shift, and I'm thinking its because of the steep gear with the 3.92s out back and launching on so much spray.

    Thanks again.

  5. #5
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    Quote Originally Posted by BigSloth View Post
    Hemituna, did you ever have any issues with some of your PD cars not wanting to complete the 1-2 shift? thats the reasoning behing my desire for this, i had a ton of trouble with the 1-2 shift, and I'm thinking its because of the steep gear with the 3.92s out back and launching on so much spray.
    Thanks again.
    The Jeeps with 4wd we use 1st to launch, but often the big power rwd cars work better using 2nd.
    Trouble with 1-2 shift is often the result of guys turning off most/all of the tq management
    These things will shift way faster and harder with tq mgmt utilised and trans tuned.

  6. #6
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    Can you post any of the edited transmission tune files please? Or at least help identify what table corresponds to what. For example there are five tow tables. One for cold weather, normal operating temperature, high altitude, 4lo 4hi.

  7. #7
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    Quote Originally Posted by Hemituna View Post
    The Jeeps with 4wd we use 1st to launch, but often the big power rwd cars work better using 2nd.
    Trouble with 1-2 shift is often the result of guys turning off most/all of the tq management
    These things will shift way faster and harder with tq mgmt utilised and trans tuned.
    I've learned a lot by trial and error, these last few tunes I've written for it have felt a lot better and have no TM modifications. The best changes for shift feel and quickness seems to have come from the torque converter settings. The ram converter settings are weird, I have an old stock scat pack file I got from the repository, the difference between the normal mode scat pack and ram is stark. The only thing I ever changed for TM was mimicking the TM settings from the scat pack file for normal mode. Figured it wouldn't hurt it.

    I'll find out in a few weeks how it does with the new motor.


    Quote Originally Posted by Spooby View Post
    Can you post any of the edited transmission tune files please? Or at least help identify what table corresponds to what. For example there are five tow tables. One for cold weather, normal operating temperature, high altitude, 4lo 4hi.
    You want to see all the settings or are you just asking about the tow haul mode? I just zeroed out the 1/2 2/1 table in all the 0-4 tables for tow haul. Press tow haul= no 2nd gear.

  8. #8
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    Digging out an old post, did anybody tried to skip other gears then first. I would like to try to skip 1,3,5 and 7 in low gear so the truck does not shit as much in low range (Jeep with 5:1 t-case ratio)