Go 2 Twister - Dana 300 Re-Indexing Adapter
March 3, 2001
Go 2 Guy Engineering has come up with a product that achieves that holy grail of "something for nothing." They've come up with a way to increase ground clearance under a Dana 300 transfer case by up to 4.25" without sacrificing vehicle stability or adding a host of other expensive modifications.
The Dana 300's well-known strength, reliability, good low-range gearing, and short length make it a desirable transfer case but its droop has always been a source of annoyance among its users. From the factory, Jeep has indexed the Dana 300 so that the front output shaft is positioned considerably lower than the rear output shaft. The reason for this is unclear but the end result is as plain as day. The front output end of the transfer case becomes a rock bashing lump that is the lowest point under the vehicle. Compounding this problem is the fact that it is positioned almost halfway between the two axles, in the perfect spot to reduce the vehicle's break-over angle by as much as possible.
Experienced shade-tree howler monkeys have solved this problem by drilling a new bolt pattern in the transmission-to-transfer case adapter. This pattern would be offset or "re-indexed" by a few degrees so as to raise the Dana 300's front output. By and large, this technique works but there are a few "gotchas" that you must be aware of:
- As with real estate, "location location location" is the key to doing this job correctly. You MUST measure correctly and ensure that your new bolt hole pattern is circular and perfectly centred around the transfer case's input shaft.
- Even with a perfect pattern, you will have to give up one of the bolt holes because there will either be interference with the webbing on the adapter or a bolt will become unreachable during the installation.
- You might be able to take a different approach and drill a new bolt pattern in the transfer case itself. However, it is even more critical that you do not screw up because replacing a case will definitely cost more than an adapter. To avoid getting metal shavings in your gears, you also need to gut the case before performing this work. The benefit to this is that you will be able to use all six bolt holes.
- You get to do this whole job over again if you decided to change the indexing.
For those of us who want an idiot-proof way to perform this job or don't have access to machine shop tools, Go 2 Guy Engineering has the answer. Go 2 Guy is Ken Blume, a mechanical engineer and an avid Jeeper with over 20 years of back country experience. He approached this problem by producing an machined steel adapter plate that would allow us to use all six bolt holes without requiring any modifications to either the transmission-transfer case adapter or the transfer case. As an added bonus, he also included 3 bolt patterns in his adapter to allow for three indexing position besides the stock location:
Designed for those who don't want to do a body lift or floor modifications.
Designed for popular 1-1.25" body lifts or floor modifications.
Requires a 2" body lift or floor modifications.
Besides providing additional ground clearance, re-indexing the Dana 300 will cause the front output to extend further toward the passenger side, allowing for additional front drive shaft clearance. With a TorqueFlite 999, this is an important consideration because it may then allow a CV joint to be used. This might also be beneficial for other transmissions as well. It might also allow a Dana 300-equipped 4x4 to be flat-towed without disconnecting the rear driveshaft or welding sling paddles inside the 'case. This point, however, is only speculation based on the fact that a horizontal case will allow all the gears to be bathed in oil during flat-towing.
As you might expect, the Go 2 Twister can also be used with any Chrysler transmission that has the same bolt pattern (ie: those transmissions that came from the factory mated to an NP231 [or similar] transfer case). So even if you have a stock NP242 or NP231 transfer case, you can use the Go 2 Twister to gain additional ground clearance.
After going through the trouble of a spring-over axle conversion and swapping in Scout axles, I decided that it would be criminal to simply get by with the Dana 300 droop. I wanted Project YJ to be all that it could be, so to speak. So, beginning next week, during the transmission overhaul, we will be installing the Go 2 Twister on Project YJ. I'll post some before/after photos, along with photos of the installation procedure.