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Dana 300 Transfer Case Indexing Ring - Product Review

Dana 300
Mark R. Werkmeister | Writer
Posted May 1, 2001
Photographers: Mark Werkmeister

The Twister Dana 300 Indexing Ring
Our chosen paths are getting more extreme, and the rocks are getting bigger. The result of this trail evolution is that enthusiasts are seeking every little edge they can get over their companions and the stubborn obstructions we all love to face. One of the biggest challenges we face is clearance; clearance under our differentials (shaved diffs, bigger tires), clearance under our axles (springover conversions), and clearance under our skidplates.

One of the limits to improving skidplate clearance is the angle of the dangle. That is, the front output end of the transfer case, typically the lowest point of the drivetrain. If you are blessed with a CJ, then you know that the Dana 300 is the single most vexing part on your rig when it comes to rock passage. The front output shaft on this venerable T-case hangs a full 5 inches lower than the rear output shaft in stock configurations, which makes it the greatest hindrance to producing a bellypan that stands a chance at unobstructed rock passage. If only you could rotate the transfer case to increase clearance.

Go2Guy Engineering has come to the rescue. Proprietor and tinkerer, Ken Blume, has developed a quick and easy adapter ring that allows the Dana 300 to be rotated, or indexed, to three different positions that dramatically improve the clearance under the Dana 300. The ring bolts to the T-case with flat-head socket cap screws. Another set of studs is then screwed into one of the three sets of holes. The new studs fit in the holes in your existing transmission output adapter. That's it. Sounds easy, doesn't it?

The thickness of the adapter is only 5/16-inch, so it does not appreciatively change the depth of engagement on the splines of the input shaft. Consequently, the possibility of a failure in transferring power is not an issue. In some cases, the seal depth will prove inadequate, so the kit includes an extra-wide seal and sleeve to extend the input shaft sealing surface.

At its highest position, the adapter ring can add 4-1/4 inches of clearance. Of course, rotating the transfer case can potentially create a few new limits of its own. You are responsible for checking such things as speedometer wiring, exhaust routing, fuel line clearance, shifter linkage, and front driveshaft clearance. You should note that the driveshaft actually swings up and away from the transmission as it rotates. This increase can be as much as 1.4 inches on the transfer case end.

On most typical installations, these potential problems will be non-issues. For those who choose the more extreme positions, though, body modifications may also be necessary. But access to a heavy hammer is pretty straightforward, and the skills needed are minimal. The final step is to fabricate a new skidplate to take advantage of all this newfound clearance.

Once installed in a rotated position, be sure you have an adequate amount of oil to provide good lubrication of the transfer case. If you just fill to the old plug location, you will dramatically overfill it A good rule of thumb is to fill the case so the oil level is just at the bottom of the intermediate shaft.

Now, a few readers are going to say, "Hey, I managed to rotate my 300 without the help of an indexing adapter." Congratulations. For the rest of you out there without easy access to a qualified machinist, the Go2Guy has solved this one for you. Get twisted.

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Sources

Go2Guy Engineering
Lowell, AR 72745

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