Harry Wagner
Contributor
The Dana 300 is arguably the best factory transfer case offered in a 4-wheel drive. Yes, an NP205 is stronger and is available in either left- or right-hand drop, but it is also heavier and larger and only offers a 1.96:1 low range. Like the NP205, the Dana 300 uses a cast iron case and helical-cut gears, but boasts a 2.62:1 low range from the factory and was available only with a passenger front output.
“The company that makes the mightiest aftermarket transfer case can also make your Dana 300 better”
As great as it is, these is still room for improvement with the Dana 300. It makes sense that the company that makes the mightiest of aftermarket transfer cases can also make your Dana 300 even better. That’s right, Advance Adapters, the people who brought you the Atlas II, have everything you need to make your Dana 300 live behind big power and turn even the largest of tires on the trail.
We did one-stop shopping with Advance Adapters to make our Dana 300 stronger and more functional. These upgrades included 4:1 low range gears for more torque multiplication on the trail and a heavy-duty (NP205 sized) 13⁄8-inch, 32-spline output shaft to replace the factory 11⁄8-inch, 26-spline output. We also added the Advance Adapters twin stick kit, which includes rod ends for all linkages and new shift rails that allow front wheel drive in low range. “Front digging” with the rear output disconnected can be extremely useful on tight technical trails, which is exactly where we plan to head after stabbing this Dana 300 back in to our latest project vehicle.
Dana 300 Specs
Case: Nodular cast iron
Internals: Helical-cut gears
Input: 23-spline (female)
Outputs: 26-spline
Gear Ratio: 2.62:1
Bolt Pattern: Round 6-bolt (most common)
Weight (lb): 85
Length (in): 11 1⁄2
Width (in): 16
Found In: ’80-’86 Jeep CJs, ’80 International Scouts (Texas pattern)
When Should You Consider an Advance Adapters Atlas?
As good as the Dana 300 is, we put $1,400 worth of parts into making our transfer case as strong as possible. Of course, you don’t have to perform all of the upgrades at the same time; you can pull out your transfer case and upgrade components as your budget allows. We performed the labor ourselves and already had a Dana 300 to start with, but if you needed to pay labor and didn’t have a core, you could easily get into an Advance Adapters Atlas transfer case territory. Two-speed Atlas II cases start around $2,400 and offer strength that surpasses even our beefed Dana 300.
1. The factory low range ratio is 2.62:1, but the gears we selected from Advance Adapters (bottom) offer a 4:1 low range. The lower gear ratio provides greater torque multiplication and control on the trail.
2. The physically larger gears required us to remove material from the transfer case housing to allow for proper clearance. A die grinder made quick work of this.
3. Only remove a little material at a time from the housing, and test-fit the gears as many times as necessary to ensure fitment without removing too much material.
4. The first snag we ran into was that the clearanced shift rail included with the 4:1 gears would not work with our twin stick kit. We had to modify the twin stick shift rail to work with the larger gears.
5. We used a 50-grit abrasive disc to modify our shift rail to clear the larger 4:1 transfer case gears. Once again, remove a little material at a time and test-fit the parts regularly.
6. We had the standard Jeep Dana 300 transfer case, and the Advance Adapters HD output added 11⁄2 inches in length. Advance Adapters makes kits for long Dana 300s and Scout Dana 300s as well.
7. The stock Dana 300 output shaft is 11⁄8 inches in diameter with 26 splines. Advance Adapters manufacturers a larger, 13⁄8-inch-diameter, 32-spline output shaft that is comparable in size to the Atlas II and NP205 transfer cases.
8. When we added the heavy-duty output shaft we upgraded to a 1350 yoke at the same time. This is an option from Advance Adapters, as the 1310 yoke comes standard.
9. The Advance Adapters cast aluminum tailhousing accepts factory Jeep speedometer gears. A cover plug is also included if you don’t need the speedometer gear.
10. Shims are included with the 4:1 gears to set the endplay on the front output shaft. The 32-spline output comes with a shim installed for the proper endplay for the main shaft.
11. We used a band saw to cut the factory mounting ears off of the aluminum shifter housing. A Sawzall or cutoff wheel could be used as well.
12. The Advance Adapters twin stick kit uses 3⁄8-inch rod ends for precise shifting. These resist binding much better than the factory shifters do.
13. The most difficult part of reassembly is aligning the shift rails, detent balls, and springs.
14. The link plate and the shift rails should be parallel with the transfer case in neutral to prevent binding. Note how the hardware mounts with the threads towards the outside.
15. The twin stick kit comes with plastic shifter knobs standard. Laser-etched aluminum knobs are available as an option.
16. The completed Dana 300 is strong and compact and makes an excellent transfer case for Jeeps, buggies, and other lightweight rigs.
