Output shaft strength

Discussion in 'OffRoad Design' started by Ryan Melton, Dec 15, 2000.

  1. Ryan Melton

    Ryan Melton Registered Member

    Dec 15, 2000
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    Someone advised me that Klune-V has experienced two broken transmission output shafts with their boxes, and they were both 23 spline Dodge. Klune confirmed they had experienced 2 broken 23 spline Dodge shafts. I spoke with Hughes Performance and they advised me that in a 4x4 application a hardened 23 spline output on a 727 TF should handle my approx 400 h.p., large tires, and a Doubler system with no problem. They advised the mentioned breakage was probably because the shafts were factory. Will a 23 spline 727 TF output stand up to 44’s, 400 h.p., and a Doubler? I would think a U-Joint would blow before the transmission output shaft. I already have a 727 with a married 203 (1979 Dodge) so I think the Doubler is definitely the way to go, but am concerned about the shaft strength where it feeds into the 203.
  2. Stephen

    Stephen 1/2 ton status Moderator Vendor

    Sep 15, 2000
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    Carbondale Colorado
    I don't have any real experience with the dodge trans shaft, but just remembering it seems like it's at least similar in size to the 27 spl. GM. I'm not sure what to tell you, but the extra gears with the Doubler will be easier on it that anything else. You won't have to put out as much power to make it really move. I also don't know of any shaft upgrades for the 727, but you might shop around some trans shops. As for mating to the 203, your best bet would be to go with a 31 spl ford pattern shaft, or a 32 spl gm type shaft. that's assuming that somebody out there makes a different shaft for the 727. If not, just go for it. I think you'll probably be OK. I've flogged on my Doubler pretty hard with the 27 spl. coupler and input on the 205 without any problems. And that's down stream of the 2:1 reduction of the 203 gearbox.
    if you're still worried about it, get a new shaft, that way it won't have any fatigue from previous use.
    If you just can't find parts to beef it up, it may mean it's a pretty isolated problem. You're surely not the first to really abuse a 727!


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