Discussion in 'OffRoad Design' started by seattlek5, Jul 2, 2001.

  1. seattlek5

    seattlek5 1/2 ton status

    Feb 23, 2001
    Likes Received:
    ...with one hand on the bender.
    Just as I thought I was getting close to having the 400/205 ready to go in my K5, I found the splines on the 400 are too short. I think I need to get a double and just get it over with. Here are the parts I have, could you let me know what else I will need to buy to finish this nightmare project. I have:
    TH400 K-case (had a 208 behind it)
    203 from a TH350 (27-spline male input)
    205 I just built and upgraded to a TH400 32-spline female input
    TH400 to 205 tall adapter

    I will also need one of your shifters to go with the doubler. How far away am I from having the right set-up? Any help is very appreciated.

    By the way what are all those levers in your rig for? (Turning brakes?)
  2. Stephen

    Stephen 1/2 ton status Moderator Vendor

    Sep 15, 2000
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    Carbondale Colorado
    Ok, first the fun stuff, there's 2 levers to control the 205, one to run the 203 gearbox, a pair for the cutting brakes, and a line-lock for both rear brakes. the proportioning valve for the rear brakes is right in there too, but more under the corner of the seat.
    OK, theres 2 ways to go with the trans and 205.

    1. we can get you an input gear that will allow you to use the 2.5" output shaft from the TH400 with your 205. You will have to replace the input gear again, but it'll work. It basically is a couple inches longer so it engages the splines. It's a direct bolt in. Price should be about $150 or so, we'll have to see for sure.

    2. Go for it with the Doubler. there are 2 ways to attach the 400 and 203:

    1. factory, find a th400 shaft that sticks out 1 1/2" from the back of case, find a factory TH400 to 203 adapter plate, and use a 32 spline input gear in the 203. We periodically have some 203/400 adapter plates available, and can get the 32 spline input new for about $140 or so.

    2. the offroad Design way: we've started development on a plate that will bolt the 203 to the TH400 using the 2.5" stickout shaft that originally was used with a 208. This is the most common shaft, which is why we're messing with it. The plate will increase the overall drivetrain length by about an inch. Then you will still need the 32 spline input in the 203 and of course the Doubler kit to bolt to your 205. Price is a little preliminary now, but should be about $225 or so for the adapter plate.

    Good news is your 205 is ready for the Doubler, and always will be since you already have the short 32 spl input. You can do the Doubler now, or use the "long" input gear in the 205 and swap it all around later.
    Hope this helps.

    Making the world better, one truck at a time.

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