"Brownie Box" Aux Trans Questions

Discussion in 'Drivetrain & Suspensions' started by TBigLug, Nov 15, 2013.

Which would you use?

  1. 3 sp. "Brownie"

    5 vote(s)
    33.3%
  2. 4 sp. "Brownie"

    4 vote(s)
    26.7%
  3. GV Unit

    2 vote(s)
    13.3%
  4. US Gears Unit

    4 vote(s)
    26.7%
  1. TBigLug

    TBigLug I Miss U Baby Girl

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    Basically four different options here. 3 sp "Brownie", 4 sp "Brownie", GV OD Unit or US Gears OD Unit.

    Truck is "potentially" 1992 Chevy Kodiak LoPro, 5.9 Cummins (mild), AT545, 60" sleeper, 9' flatbed, 245/70R19.5 tires, weight ~10,000#'s, pulling 10,000# gooseneck horse trailer or equivelant (sp?) size camper. I don't know what ratio the rear end is but the two options I found on the heavy truck parts websites was 4.33:1 and 4.8:1. For the sake of discussion we'll assume it's a 4.33:1 since the truck started life as a 366 gasser.

    Using http://www.ringpinion.com/Calculators/Calc_RPM.aspx and 245/70R19.5 (33.5") to figure out rpm's and such, 55 mph gets 2,389 RPMS's and 65 mph gets 2,829 rpms. Fine numbers for a gasser but way to high for a diesel. I would like to get down to the 2,000 rpms at 55 and 2,300 rpms at 65.

    I've never had one or used any of the above so I'm looking for some input for the guys who have. Here's the questions...

    Can a "brownie" be mounted "divorced"? I'm thinking about where the midship bearing is.

    Will a US Gears unit hold up to heavy towing?

    With a "brownie" is it possible to leave it in OD while cruising around empty then just leave it in Direct for towing? The AT545 has enough gear reduction (3.45:1 1st) that even with it left in OD (20% reduction) still leaves you at 2.76:1 still deeper than a TH400's 2.48:1.

    Where do you even find the old brownie boxes and is there anyone left to get parts from?

    So, enough rambling, on with the ideas and suggestions. Hoping this will spark some ideas and help anyone else who is thinking of something similar. And remember "THEORETICALLY" is the key word here. Just thinking ahead, don't even have the truck yet.
     
  2. TBigLug

    TBigLug I Miss U Baby Girl

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    Just learned something new, got an email from Kathy Stehn and US Gears hasn't made the aux trans in years. Lol, looks like these new heavy duty Allison OD's are removing the niche for auxiliary overdrives.
     
  3. Smokininmo

    Smokininmo Registered User

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    I have an old 3 spd Brownie out of an F600 believe it was made be spicer. It is double underdrive 1:1 and .56 overdrive. Ive had it for years bought for a project that never came to be. Would sell it if your interested.
     
  4. Smokininmo

    Smokininmo Registered User

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    And to answer you question Yes this is made to be a divorce mounted trans. Has u joints on both ends. Cant answer the other questions for sure.
     
  5. m885

    m885 Registered User

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    Brownie box for sure, but remember they need a small air source to do the shifting, assuming it has juice brakes.
     
  6. Smokininmo

    Smokininmo Registered User

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    The one I have is a manual shift..........Guys used to run them on hotshot rigs. Make em a twin stick. I've heard of running a stick brownlite behind an auto, just gotta shift it when the rpm is right........And My overdrive is .76 not .56 I think.....Been a couple years since I looked it up. By my calculations assuming your transmition in high gear is 1:1 your ring and pinion is 4.33:1 and tire height is 33.5" a .76 overdrive should put you at about 2050-2100 rpm at 65. That cummins would love it.
     
  7. TBigLug

    TBigLug I Miss U Baby Girl

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    I think one would work for me behind an auto cause I wouldn't be shifting "on the fly". I would most likely leave it in OD for cruising around and shift it into Direct (from a stop) when I pull my trailers.
     
  8. Jake2670

    Jake2670 Registered User

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    I'm working on kinda the same project, think I have a source for rebuilds, n prob parts, c if I can find em. Smokin, we pretty close, if he don't take I'd like 2nd chance, I have box located in a 48 GMC, gotta get under it n see what it is, it too has a floor shifter, I was thinking of trying to put a air piston on it, anyone ever do that? I do want to split gears, n thats one concern I've had, asked n no good answer on how well they work that way.
     
  9. Smokininmo

    Smokininmo Registered User

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    Sure thing Jake. There is a shop here in Springfield that claims they can get any part for that trans as well so I dont think that would be a problem. There used to be a guy around here that ran a hot shot in the 70s and 80s it was a 1970 Chev 1 ton streched out with a custom sleeper. He ran a 500 CID Cadillac Motor and turbo 400 trans with a three speed brownie. Just shifted when the RPMs where right. If your a driver splitting gears shouldnt be a problem.
     
  10. Jake2670

    Jake2670 Registered User

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    yeah, just takes practice, box I found is so old, not sure was built for splitting,idk, my rig is a 84 C3500, has a 6.2L with NV4500 now, she getting 5.9L down the road, but had more gears bad right now and be great behind 5.9L :D Do you know how old ur box is?
     
  11. Smokininmo

    Smokininmo Registered User

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    I dont remember You could probably look it up with the serial number though if you found a good shop. It was set up to split gears in the truck it was in though. it's syncroed from what they told me.
     
  12. Jake2670

    Jake2670 Registered User

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    Yeah, I gotta get by there n take pics n get #s, but still interested n urs too. He said this box was 2 spd, but I'm pretty sure he never seen it really used, its in truck his dad used to move a Allis D-3 dozer, I got dibbs on the dozer too :-D
     
  13. Smokininmo

    Smokininmo Registered User

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    It is possible that it only has a low gear and straight through. Mine was in an f600 so its a bit bigger than the little 1 ton trannys. the ones like mine with the overdrive where not as common.
     
  14. Jake2670

    Jake2670 Registered User

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    i c this is in a pretty big truck, i'll c if I can post pic, prob at least 1.5T, this is parts try, other one has flat dump, it has the old style babbitt engine though, but still cool truck.
     
  15. Smokininmo

    Smokininmo Registered User

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    That may be close to the same size then. If we can get numbers we can figure out if it is two or three speeds and what the ratios are. Also since mine is out of the truck i can shift it and spin it. It is obvious what gear you are in by the different speeds of the input and output shafts.
     

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