Step By Step
You need to remove the transfer case from the vehicle to install the kit. Youll need to remove the access cover, rear yoke, and speedo gear, which gets transferred to the new housing. Since the case was apart, we removed the intermediate shaft and gear for inspection, but this isnt necessary to install the kit.
Remove the six Allen bolts that hold on the input retainer. Remove the whole thing and set it aside.
Remove the five bolts holding the tailshaft to the case and gently pry it off. For those of you who home-brew, you can melt it down to make beer cans.
Advance Adapters recommends using a puller to remove the tapered bearing from the output shaft, but since we were going further into the case, we used a brass drift to knock the shaft out.
The 13/8-inch, 32-spline Advance Adapters output shaft on the right is massive compared to the 11/8-inch, 26-spline stock unit. The Advance shaft is 1/2 inch longer than stock, so you may want to check your driveshaft before any big-air takeoffs.
More comparisons. The Advance tailshaft (right) is a modified Atlas piece and houses a larger bearing.
The input shaft is fed through the slider and gear, and the included thrust washer and bearing are installed. You must use the included washer for proper alignment. Dziezyk used a length of tube to drive the bearing onto the shaft.
Next, the speedo gear snap ring, speedo gear, and shim race are installed onto the shaft. You must use the shim race included in the kit, as its tailored for each specific input shaft and tailhousing.
Install the input retainer with the stock hardware. Dont forget to use silicone on the mating surfaces.
The tailhousing is bolted to the case using the supplied Allen bolts. Install the supplied yoke and torque the nut to 150 lb-ft. You should be able to spin the gears easily by hand unless you messed up. If you cant, go back and make sure everything looks good.
Finally, roll the supplied O-ring onto the stock speedo housing and install the speedo gear into the tailshaft. If you installed the kit on an early short version Dana 300 youll need to buy the later speedo housing, gear, and retainer clip from Jeep.
Its got a beefy cast-iron case, an all-gear design, and twin shift rails just like an NP205. But its got a little weenie output shaft just like a Kia Sportage. Well, maybe its not that bad, but compared to the rest of it, the 11/8-inch, 26-spline output shaft has caused way more headaches for hard-core four-wheelers than any other part of the Dana 300 transfer case. Imagine throttling up a steep, off-camber hill only to hear a sickening pop followed by the sound of your rear driveshaft whacking the floorboard of your rig. Youd have about 0.02 second to enjoy it before you needed to hit the brakes to prevent an unwanted reverse and tumble.
Thankfully, for hundreds of hard-core enthusiasts, Advance Adapters has come out with a tailshaft upgrade kit that includes a monstrous 13/8-inch, 32-spline output shaft and aluminum tailhousing that uses a bigger bearing. The kit even includes a 1310 yoke since the yoke for the stock shaft wont fit the larger-diameter Advance piece. Once installed, the new tailshaft kit is ½ inch longer than stock, but that shouldnt be enough to necessitate driveshaft modifications.
We took our parts to MIT in El Cajon, California, where Rick Dziezyk showed us how to replace the weakest part of the Dana 300. Although the installation doesnt require the removal of the intermediate shaft and gear, Dziezyk needed to check the condition of the needle bearings for wear in this particular application. Since the case is out of the vehicle and partially disassembled, nows a good time to diagnose any weird noises that may have been emanating from your case.