JEEP DANA 300
In 1980 Jeep introduced the rugged and dependable Dana 300 Transfer case. It would prove to be an incredible success. This light weight compact unit set the bar for other transfer cases to follow. Even today many consider the Dana 300 as the best transfer case ever used by Jeep Dana 300 TC
History: The Dana 300 was the result of engineering advances put into play by the Dana Corporation. Prior to the Dana 300, Dana was limited to modifying and perfecting the Dana 18 and subsequent Dana 20. Improvements were clearly needed as Dana saw the writing on the wall to American needs and wants: Strength with Silence. Clearly this was not an easy task for Dana as the two don’t necessarily go hand and hand. Development for the Dana 300 began in August of 1976. Engineers were focused on some key points while still maintaining certain parameters. These parameters were weight, size, centerline, strength, manufacturing costs and quiet running gears. Engineers submitted their final design changes for approval in July of 1978. Although not leaps and bounds from other transfer case designs like the Dana 20 or NP205, The concept models produced by Dana were “dead on” and destined for ultimate success. By 1979 the stage was set for the first introduction of the new helical geared Dana 300. The first candidates were the 1980 Jeep CJ and the I.H. Scout.
Identification: The Dana 300 was a cast iron transfer case featuring a passenger-side front drive shaft. The rear output shaft was centered or in line with the transmission output shaft. New for the Dana 300 was a round, circular six-bolt front mating surface pattern. The previous Texas bolt pattern from the Dana 20 had been retired with the exception of the Scout Dana 300. The case was generally smooth with little webbing as seen with modern transfer cases. One unique design change was the 23 spline female input for the Dana 300. The previous Dana transfer cases were equipped with a coarse transmission output shaft having the transfer case input gear mounted and retained. The new 23 spline female input basically made the Dana 300 an isolated unit where the input rode on its own bearing and seal. This input assembly was retained by a removable aluminum indexing retainer. The helical cut input gear was manufactured to accept the new input which had 31 male splines on it.
The Dana 300 weighed in at approximately 85 lbs. The unit was clocked down on a 23 degree angle. The overall width was 16”. The output shafts were 26 splines on both the front and rear outputs. The factory configuration used 1310 non-cv yokes front and rear. The first Dana 300 units introduced in 1980 measured approximately 10-1/2" in overall length. This was known as “The Short 300”. In 1981 this length would increase to 12”. The added length was not a result of a longer cast iron case as many are misled to believe. The difference was a design change to the rear nose cone area of the Dana 300. The short 300 was factory with a nonadjustable fixed gear for the speedometer in the rear aluminum nose cone. This design proved difficult for calibrating the speedometer for tire changes or ring and pinion swaps. The newer Dana 300 used a longer rear output and aluminum nose cone. A removable speedometert drive with a replaceable plastic gear replaced the older non-serviceable design. This allowed the consumer to easily exchange his plastic gear for another with a different tooth count. The design change proved so successful that Jeep continues to use this basic design on a majority of their transfer cases even today.
Jeep offered 4 different transmissions for use with Dana 300. These would include the SR4, T4, T5 and T176. The T176 was the strongest and shortest of these applications
Features: The Dana 300’s compact design and durable construction was accepted with huge fanfare. Not only was the transfer case stout but the case was significantly quieter than the Dana 20. The Dana 300 had other features adding even more respect for this unit. Obviously the 2.62 low range was the first appreciative offering. This was a significant improvement over the 2.03 previously offered by the Dana 20. The actual internal gear shifting design evolved from a sliding gear to a sliding clutch sleeve with fixed speed gears.
The 300 was introduced with a single shifter for the transfer case. The unit shifted from top to bottom 4L-N--2H-4H. The transfer case had a large aluminum shifter base on the front of the transfer case where the single lever assembly mated with two shifts rails. Inside the shifter housing were interlock pills between the shift rails. The original shifter design was clearly not the best design for the transfer case and many feel Dana engineers may have contemplated offering the Dana 300 as a twin stick option. This however was never followed through. The aftermarket would take care of that and many other options.
Jeep Dana 300s all use a 23 spline input. Some of the adapters we manufacture include a new Dana 300 input with a different input spline and other adapters retain the stock input. The various Dana 300 input shafts we manufacture include a 10 spline, a stock 23 replacement, a long 23 spline which is .750” longer spline engagement than stock, a 27 spline, a 21, 29, 31, 32, and 35 spline. Therefore, if you obtained a Dana 300 from a salvage yard, please verify the input spline.
Dana 300 input shaft:
PN52-0203 - Dana 300 35 spline input shaft
PN52-0208 - Dana 300 32 spline input shaft
PN52-0229 - Dana 300 29 spline input shaft
PN52-2910 - Dana 300 31 spline input shaft
PN52-3001 - Dana 300 23 spline input shaft Stock replacement
PN52-3002 - Dana 300 long 23 spline input shaft .750” longer
PN52-3021 - Dana 300 21 spline input shaft
PN52-3034 - Dana 300 34 spline input shaft
PN52-6309 - Dana 300 27 spline input shaft
PN52-9810 - Dana 300 10 spline input shaft
The aluminum index retainer incorporates a front seal to protect the transfer case fluid from entering the transmission. The transmission adapter housing normally has a seal that is installed with the open side towards the transmission. This seal can be omitted on transfer case adapter installations, provided a gasket or silicone seal is used in between the adapter and the transfer case. The original Jeep adapters have a small weep hole that is located between the two seals. This weep hole is an indicator that one of the seals has gone bad and needs replacing. We do not use this concept on the transfer case adapters that we manufacture.
The Jeep Dana 300 has a stock rotation of approximately 35 degrees. All of the adapters we manufacture for this transfer case have the provisions for this rotation. Most of the adapters have two sets of six adapter-to-transfer case mounting holes. The illustration (left) shows the correct holes to maintain this degree of rotation. The second rotation option is used for New Process transfer cases.
With ground clearance being an issue or concern with some vehicles, we also offer a Dana 300 rotation kit that allows the transfer case to be clocked up higher to provide additional ground clearance. The rotation kit will require transfer case shifter handle modifications and possible floorboard modifications. This kit comes with a new 23 spline input shaft and adapter plate to maintain proper indexing, P/N 50-8604. Using this indexing plate with one of our adapters that uses a different spline count than the 23 spline will cause a loss of some spline engagement and may not be recommended.
TRANSMISSION & TRANSFER CASE SUPPORT PLATE:
All of the adapters we manufacture offer a support pad machined on the casting. In most cases, this pad will not line up with your original skid plate mounting slots. Jeep vehicles 1980-86, have a boxed-in frame that has the skid plate mounting holes embedded into the bottom of the frame rail. It makes it difficult to move the crossmember due to this enclosed frame. On most applications, we found that retaining the skid plate in the stock position and adjusting the mounting slots on the skid plate works the best. On longer transmission assemblies, it may be necessary to modify the skid plate for front driveshaft clearance or relocate & mount the skid plate further back on the frame rails using 4 of the 6 mounting holes. On some applications, a spacer between our adapter housing foot and our new rubber crossmember may be required. We offer a 2” spacer for such applications.
If you are planning to reuse your stock rubber support, use PN716017 to assist in the mounting. We also offer a new support bracket which replaces your stock transmission rubber support.
PN716021 - New rubber support (Jeeps 1980-86)
PN716017 - Aluminum adapter block (used to help retain your stock rubber support)
PN716048 - 2.0” Spacer between adapter foot and crossmember
FRONT DRIVESHAFT CLEARANCE:
On most vehicles, we have tried to allow for proper clearance. However, we are unable to allow for this with some automatic transmissions. These applications will require the centerline of the drivetrain to be offset 1” to the driver’s side, and you will be limited on your driveshaft diameter.
TRANSFER CASE SHIFTERS:
The Dana 300 shifters are always supported off the front of the stock transfer case. On some of the truck 4 speed and NV4500 adapters, the shifter support and pivot shaft may need to be modified to fit to these transmissions. Most applications will not require any modifications.
Another option for the Dana 300 transfer case is a twin stick shifter. Our twin stick application requires the installation of two new shift rails. This kit is a securely mounted assembly off of the stock aluminum shifter housing. The new shifter rod allows a heim joint linkage for a smooth, positive shifter motion.
PN403300 - Deluxe Twin Stick kit (with new shift rails included)
(If using this kit with a 4.1:1 gear set, the shift rails do require modifications)
PN403330 - Aluminum Knobs for Twin Stick kit
The new deluxe twin stick kit does require the installation of new shift rails into your transfer case. This kit allows the Dana 300 to be shifted to the following configurations: 2WD High, 4WD High, 4WD Low, Rear Low, and Front Low. This is a universal-type kit that may require the handles to be bent for specific applications.
PN400300R - Dana 300 seal and bearing rebuild kit
HEAVY DUTY DANA 300 OUTPUT SHAFT:
About the only weakness we’ve seen on the Dana 300 is the output shaft. The stock Dana 300 output shaft is a 1-1/8” diameter, 26 spline. We now offer a new, larger 1-3/8” diameter 32 spline output shaft for this transfer case. The Dana 300 has two different stock tailhousing lengths. We offer kits to fit both lengths of the Dana 300 tailhousings.
PN50-3032A - Heavy duty 32 spline Dana 300 output shaft without yoke.
PN50-3034A - Heavy duty 32 spline Dana 300 short output shaft kit without yoke.
Kits come complete with a new tailhousing, output shaft, tapper roller bearings, yoke, and speedometer drive. If you require strength and reliability, the Advance Adapters Dana 300 output shaft kit is a must have.
To install the H.D. output shaft into the Dana 300 transfer case, the transfer case must be removed from the vehicle. Once the transfer case is out, the front retainer, the stock yoke, and the access cover must be removed. Next, the stock tailhousing gets removed and the tapered roller bearing must be pulled off the output shaft. With these items taken off, the stock output shaft will exit out of the front of the transfer case. The new H.D. output shaft kit comes loosely assembled into the new tailhousing. The new tailhousing and shaft have had the proper end play set with shims on the output shaft. The shim set should not be changed or modified. The new kit gets installed exactly the same as the old, small diameter output shaft that was removed. This is a short description of the install procedures. A complete set of instructions is included with our H.D. output shaft kits.
Our kits are 1/2” longer than the stock Dana 300 tailhousing, and 1-1/2” longer than the short version Dana 300 tailhousing. The 3.5” short version tailhousing will require driveshaft modifications since our kit is 1.5” longer than stock.
Note: When replacing the short version Dana 300 tailhousing with our new tailhousing, you will gain speedometer calibration options.
The Dana 300 would serve the CJ7 models until 1986. The Dana 300 transfer case would be replaced with the lightweight NP207 in 1987.