Auxiliary trans

Discussion in 'Transmission & Transfer Case' started by 1984dually, Nov 28, 2018.

  1. 1984dually

    1984dually Full Access Member

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    recently swapped out a set of 3.73 gears to 4.56 in my 84 Dually. Nice for pulling but would like more gear for running around empty. Current trans is a 4L80e. Anybody ever add a auxiliary trans like a two speed brownie?
     
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  2. 84 M1008

    84 M1008 Full Access Member

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    Put a Gear Vendors on it. I'm swapping out the 4.56 gears to 3.73 on my M1008 so I can run the 6.2 on the highway without having the engine fly up through the hood. You can split each gear with the Gear Vendors also depending on the load you are towing.
     
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  3. SquareRoot

    SquareRoot Full Access Member

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    I'm running a th400 with 4:56 gears. I just want an OD so I don't redline trying to do the speed limit. And then theres guys who have an OD and they want another! Lol
     
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  4. 1984dually

    1984dually Full Access Member

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    Gear venders out of my price range and they don't recommend towing in OD. On flat ground I did just fine with the 3.73 set up. Lots of hill pulling here and the reason for the 4.56. Rpm at 60 went from 1700 to around 2100.
     
  5. Matt69olds

    Matt69olds Full Access Member

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    What’s wrong with 2100 rpm? If a gear vendor is not in the budget, a 4L80 is your only other option, and I doubt you could do that any cheaper.
     
  6. 84 M1008

    84 M1008 Full Access Member

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    The other solution is a 700R4. In lockup, it's essentially a 5 speed dropping another 200 Rpm's because of no torque converter slippage. In a gas engine it's not that much but in a diesel it makes a big difference .
     
  7. Matt69olds

    Matt69olds Full Access Member

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    If gear vendor is advising against towing, I’m guessing the payload is far beyond what a 700 would be reliable. Gear vendor is suppose to be good to 1500hp, and was originally designed for motor homes and RVs. I can’t imagine why they would advise against towing. I know the offer a deep sump pan with provisions for coolers.
     
  8. SquareRoot

    SquareRoot Full Access Member

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    A 700 in a 5k# truck is not an option. Had a built 700 in an El Camino and it worked fine. Probably save the money and get a good used of LS/4l80. I've learned my lesson on going backwards technology wise.
     
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  9. 84 M1008

    84 M1008 Full Access Member

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    What do you mean by 'built?
     
  10. Blue Ox

    Blue Ox Turning Diesel Fuel Into Fun

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    I get the impression from reading their material that it's not about the overdrive unit itself, but where the engine power curves end up at the lower RPM that make it unsuitable for towing.
     
  11. rpcraft

    rpcraft Full Access Member

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    Plenty of 700R4's went behind big blocks and lasted ages. Just add a trans cooler and make sure its not rebuilt by a hack and it should be fine. Otherwise you can go with a 4l80e and get a trans controller. The GM 0411 PCM can be used as a stand-alone controller as well as the ones that are made by companies like TCI and whoever else but those things can be quite spendy and the 4l80E still does not have as good as a low first gear as the 700r4/4l60e does... Just offering some feedback.
     
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  12. highdesertrange

    highdesertrange Full Access Member

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    if you are getting that a Gear Vendor shouldn't be used for towing it's not because of the strength of the unit it's because you are out of your power band and would be lugging your engine.

    double overdrive rarely works. you would need a super low axle ratio and or massive increases in the speed limit.

    highdesertranger
     
  13. Croc1990

    Croc1990 Full Access Member

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    Or this...
     
  14. CSFJ

    CSFJ ----------------- Supporting Member

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    Oh, yeah, that's great. IF, you don't mind driving something that looks like a refugee from a junkyard. I'm sorry, but the whole point of an automatic trans, is that it's AUTOMATIC. Why every time someone comes up with a more complicated way to do something half-assed, it gets treated like the greatest thing since sliced bread, is beyond me. yeah, that looks much better than hooking up a controller, putting it in drive and enjoying the ride. This world really needs some chlorine dumped into the gene pool.
     
  15. Croc1990

    Croc1990 Full Access Member

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    I saw it a few years ago was left kind of confused but whatever to each their own.
     

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