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gm 6 speed auto

Discussion in 'The Garage' started by rancid, Oct 9, 2006.

  1. rancid

    rancid 1/2 ton status

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    anybody have any info on the 6 speed auto in the newer trucks. i thought might help get the best mpg and power out of my 502. any adapters to mate them, or are they needed. im wanting to put this into my 71 4wd crew project.
     
  2. ryan22re

    ryan22re 1/2 ton status

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    The best I can tell, they are not available in the trucks yet, but are available in the cadillacs with the northstar. Which means the goofy bellhousings. Have to wait till they put them behind a 6.0 in a truck.

    There are several designations of this transmission, like the 6L50 or the 6L80 with the last two numbers indicating how much torque it can handle.

    http://media.gm.com/us/powertrain/en/product_services/2007/Spec%20Sheet/Transmissions/2007%20Automatics/07_HydraMatic_6L80_MYC.xls

    That's the specs on the caddy version 6L80.

    http://media.gm.com/us/powertrain/en/product_services/2007/Spec%20Sheet/Transmissions/2007%20Automatics/07_HydraMatic_6L90_MYD.xls

    That's for a truck spec 6L90. (note you need Excel to open the links)


    The good thing is they have an intergrated transmission controller in the tranny itself. No idea on how to make them work as I'm pretty sure they communicate via a GMLAN network which would make it difficult to adapt to a non computer engine to it. Probably have to wait until the aftermarket steps up with something (manual valvebody or GMLAN interface) to make it work.

    Good luck with your swap.
     
  3. neverendingproject

    neverendingproject 1/2 ton status

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    Only thing I can tell you is its gonna be $$$$$$$$$$.
     
  4. rancid

    rancid 1/2 ton status

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    what do you think about a t56 manual trans out of like a newer vette or camaro, it should be able to handle enough power.
     
  5. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    What do you have now? For the money (and what you could do now) a 4L80E and a stand alone controller can handle a lot of power and is available in tons of vehicles that have been on the market for years so you could snag one from a wrecked truck.

    this was on wikipedia....
    http://en.wikipedia.org/wiki/GM_6L80_transmission

    says they are in the '07 Yukons, Tahoes, Escalades, etc. so that takes care of the funky Northstar bellhousing issue if you wanted to go that route...

    -Avery
     
  6. bowtiepower00

    bowtiepower00 1/2 ton status

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    AFAIK, GM is only able to keep up with production demand at this point, I would expect that it will be a year or two before you'll be able to purchase one. Having six speeds isnt going to increase economy with an engine that has as much power as a 502. The NV4500 and 4L80/85e would be the best choices, IMO. The NV5600 weighs about 100lbs more than the 4500 and the extra gear doesnt change the overdrive ratio. You could look for an Allison trans from a Duramax or 8.1. If economy is really important to you, look into diesel.
     
  7. DEMON44

    DEMON44 Low-Tech Redneck

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    OH ya the 5600 is over 100lbs more than a 4500. the 5600 may handle more input TQ but the gear ratios in the 5600 are better suited to the deisel power band. with my cummins and 4500 my 3-4 shift is too wide for my likeing the 5600 keeps the ISB in the sweet spot.
     

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