Mitsubishi Transfer Case to Tera Low231 NP231 ...
Update: April 28, 2008 The doubler is finished and ready to bolt in. Its now sitting at the shop with the Terra Low231 t-case so I can do mock ups to make sure everything fits correctly and also to help make sure I don't forget something critical. There wasn't much of interest in getting the block off plate welded in. I had the machine shop surface the entire case half to help insure there are no leaks. It wasn't horrible - not off by more than 30 thousandths. I did take the time (I was bored) to have the shop weld up the two center divots (stops) in the doubler shifter mechanism - 4HI and N - and then I ground the weld down and polished it up nice. I figured that there wasn't much of a point to having stops in the shift sequence for something that doesn't exist anymore. Besides, if someone else has to drive it'll be a little less confusing.
The adapter shaft is moving along. The shop cleaned it up and drilled the center hole for the female end. I'm waiting for them to cut the electrode so they can stick everything in the EDM and cut the female splines. Hopefully that'll happen tomorrow or Wednesday.
They finished cutting and welding the last revision of the transfer case support bracket Friday. I hope. I test fit everything and this time it appears I got all my measurements correct and didn't forget anything. You can see the support mounted to the doubler plate in the picture following the mockup of the new adapter. I counter sunk the lower bolt anyway just so I wouldn't have to make the slot any larger than necessary. It's probably more than I need or will ever use but the slot gives me enough room to rotate the doubler a good amount if necessary. I doubt I'll have to mess with the doubler at all but the plan is to get EVERYTHING completely done and run through several mock ups before actually hauling it all to the garage and swapping things around. I want to make sure that if any adjustments are necessary they can be made right then and there and not require modifications or return trip(s) to the machine shop or anywhere else.
For those wondering: The slightly covered counter sunk hole to the mid left is the bolt for the shift assembly shaft. That's bolted in before it all goes together so there's no problem with it being covered up by the support. The slightly covered counter sunk hole to the mid right is another story. I don't know how much I will need to shift things - if at all - and I figured rather than guess and remove metal where I don't really want to remove metal I'd leave that as an 'on the spot' modification. Once I'm sure things are set I'll take my RotoZip and snip out a little bit to clear the alan head wrench or the whole bolt if necessary. Same goes for the lower drain plug at the lower left.
The Terra Low231 shifter mount plate for the tunnel and the cable mount bracket are both due to be picked up this week. All I have left is the cable mount bracket for the doubler. I've been kind of holding off on that until the adapter is closer to completion. I'll probably get that drawn up this week and off to the laser cutting shop by Monday. That's the last piece and then everything goes to get treated so it doesn't rust.
I put everything together this week to get an idea of what goes were, etc. Looks good but the length is pretty intimidating. I don't think the guy doing the adapter is at all convinced that it'll actually fit in my Sport. :-) You can see the cleaned up welded in block off plate on the doubler. Nothing real fancy there. I'm still toying with installing a drain plug - a la NathanC. :-) I'm not quite sure the plug will clear the drive shaft yet. You can also see the redesigned shortened shift arm bolted to the doubler. It's shown in 4LO. 2WD would be back towards the case (down in the picture) . I left 1/4" of clearance between the lever and the housing so I ended up with about 2" of travel in the lever. Figured decreasing the angles the cable cycled through would cut down on wear and tear on the cable.
So, from top to bottom in the two mock up pictures - 5-speed transmission tail shaft housing, new adapter, doubler, transfer case/doubler support and Terra Low231 transfer case. It's hard to believe that the entire assembly is only about 9" longer than the stock transfer case.
I did find out something interesting the other day regarding the electronic version of the 4WD indicator switch on the NP231. The plug is a standard WeatherPak two prong male plug. Nice! I picked up two for about 5 bucks from a local speed shop. MUCH better than the $37 dollars EACH Jeep wanted to charge!
So, if I get around to it I'll order the rear drive shaft. Probably that will have to wait until next Monday. End of the month is busy at work so I doubt I'll have time until Saturday to measure for the length.