Mitsubishi Transfer Case to Tera Low231 NP231 ...
Update: March 5, 2009 It's been a while since the last update. This hasn't been a real time consuming or complicated project. Its just taken some time for everyone to get their parts completed.
It's finally time to install everything! I striped out the old transfer case and installed the new adapter, doubler and transfer case assembly. I had a flat bed haul it to Four to Go here in Wheatridge where they built the cross member and installed the a new rear, CV style slip drive shaft from Front Range Driveline.
Driveable again, I took it back to the garage and spent a few hours wiring in the speedometer using the Dakota Digital SGI-5 speedometer adapter and 2WD/4WD switches and running the doubler and transfer case vent lines up inside the engine bay above the water line.
The assembly so far has been pretty painless and incident free. A transmission jack is a MUST for this project. Trying to manage the doubler/transfer case assembly even with a big floor jack is awkward. That is a LONG assembly!
So far, the worst problem I've run into is a leak at the adapter drain plug. I need to either get a better drain plug or a different gasket for the existing drain plug.
All the wiring is installed. The Jeep pulse generator mated up with the Mitsubishi speedometer using the Dakota Digital SGI-5 C adapter without a hitch. OK, without a hitch once I figured out that the Jeep pulse generator requires that the SGI-5 dip switch 1 be set to the ON position.
The SGI-5 documentation is pretty good and combined with the few write-ups available on the Web I was able to put together a wiring diagram that would work for me. Some notes (besides dip switch 1):
- Everything I read stressed that the SGI-5 should be wired into the same circuits as the speed sensor. Since the Mitsubishi power lead (B-W) supplies 12V DC I taped it to provide power for the SGI-5.
- Even more stress was placed on making sure that the SGI-5 was on the same ground plane as the pulse generator. I taped into the Mitsubishi ground lead (B) to supply ground to the SGI-5. Since this is the 'Sensor Ground' the wire is run to 'Sensor Ground' on the SGI-5 - NOT 'Ground'.
- For some reason Output 3 caused the speedometer needle to jump slightly every once in a while. The documentation suggested switching to Output 4 so I figured I'd give it a try. Changing to Output 4 seems to be working fine.
I ran into a little glitch with the wiring of the NP231 electric 2WD/4WD switches. I found out after wiring both switches in parallel to the Mitsubishi 4WD Sensor Switch harness that the Mitsubishi 2WD-4WD Sensor Switch harness needs to be run in a closed circuit. Easy enough to snip off the switch and then use a butt connector to connect the two free wires - I just wish I'd known that before installing the wiring so I wouldn't have had to do rewire that part while upside down and half wedged into the tunnel.
The new transfer case support cross member is in. It hangs down a bit further than I'd like but there's not really a lot that can be done about that. I dropped the original transfer case cross member 1/2" to increase clearance between the new transfer case and doubler and to give me just a tad more space between the tunnel and the top of the transmission, tail shaft housing and the new adapter for the shift assembly and cable.
Dropping the original cross member had one positive, unintended side affect. Due to the length of the new assembly the drop was considerably more than 1/2" at the rear output yoke. The result was that the pinion angle ended up not being off by nearly as much as I'd originally calculated. In fact, if I remove the 4 degree shims currently in the springs the alignment should be dead on.
The new CV style rear drive shaft is great! It is a definite improvement over the old Mitsubishi unit. The original front yoke assembly had seen better days.
The next major piece of this Frankenstein puzzle is the front drive shaft assembly. A single piece drive shaft wouldn't fit with the original forward transfer case cross member as the driveshaft would intersect the cross member at some point in its travel. The other, much more serious issue is the length of the new drive shaft. Moving the front output yoke almost 19" further back means I'll have close to a 40" drive shaft; of itself that would not be problem. Unfortunately, the drive shaft would now be the lowest point on the vehicle and stretch from just behind the center-point of the vehicle to the front axle; dangling close to a dozen inches below the chassis. All the better to land on a ledge with, says I!
I'm not interested in seeing that vision become reality so I'm opting for a two-piece drive shaft. That should be done within the next week. A two piece will keep the majority of the drive shaft within the tunnel and out of harms way and also allow me to use my front axle in its original configuration. We'll see how this goes. The angles are a little weird but the driveshaft shop seems to think they can get it pretty close if not dead on. I'm keeping my fingers crossed it's the latter.