Dana 300 swap from Dana20

[marc59]

Have a CJ7 AMC 304 with Borg Warner T-18 . Want to swap out my Dana 20 for a Dana 300 . Is it a clean swap or do I need some sort of hardware to make it work?

 

[HackFabrication]

You'll need to adapt the T-18 to the Dana 300 . Adapting the T18 & T19 Transmissions to the Jeep Dana 300 Transfer Case

Skid plate/cross member may need some modifications. Drive shafts may need some modifications.

 

[Posi]

Below is the T-18 I use to mate to the Dana 300 . I removed the Dana 20 , adapter, and b-housing.





The first thing you have to check is if the adapter came with the correct 23 spline mainshaft because they make a 27 spline for a Ford T-18 as well.

The adapter has 2 bottom mounting holes that the T-18 does not so I have to drill and tap the case. I installed the adapter with 4 of the 6 mounting bolts and scribed the case. I used whiteout as a base to help ID the marks.



I then removed the bearings and mainshaft. There are 22 roller bearings that will fall to the bottom of the case.

Bearings, mainshaft, retaining and lock clips

 

[Posi]

Just a note about removing the mainshaft bearings, they make a bearing remover that slides behind the bearing snap ring that makes removing the bearing a breeze but it’s not needed. After removing the snap ring I used a brass drift working from inside the case to remove the rear bearing. I left the lock ring on the front bearing and used a dead blow hammer on the tip of the clutch shaft to remove the bearing. Both front and rear mainshaft bearings are ball bearing type opposed to the cylindrical or tapered roller bearing.


Next remove the lock plate from the rear of the case that locks the countershaft and reverse idler gear shaft. I tapped out the countershaft to the rear of the case using a brass drift once the shaft was out I was able to remove the countershaft gear assembly. The countershaft assembly has 88 roller bearings and the reverse idler has 74 bearing rollers.


The reverse idle gear shaft does not come out as easily as the countershaft because the front of the shaft is located inside the case unlike the countershaft that is on the outside of the case. I used a long extension and dead blow hammer.


Note the magnet at the bottom of the case it’s a well thought out option.





I cleaned the case for a second time and chased all threads as well. I used a 5/16 bit and drilled 2 holes for the adapter.





After cleaning the burs I tapped the hole using a 3/8” 16 tap. You can drill a hole in a block of wood and use it to keep the tap going in straight I chose to use a torpedo level it worked for me.


I test fit the adapter and all holes lined up perfectly.





I cleaned the case of metal filings, washed, and prepped for paint.

 

[Posi]

While test fitting the adapter to the back of the Transmission I noticed the supplied bolts are too long and will interfere with the reverse idler gear and the front clutch assembly. There are two other bolts that are not in the pic that are too long as well.


One bolt was a 1/4” too long and the other three 1/8” so I used a drummel to cut off the tips and cleaned them up with a fine file.





After cleaning and inspecting the small parts I decided to purchase a new kit.





I used a 1” dowel with some assembly grease to install the 88 roller bearings and 6 washers.





I put some stickum on the two rear washers and the front thrust washer. I used the two shafts installed just enough to help hold them while I installed the counter shaft.





On the second try I dropped the countershaft in.





I removed the reverse idler gear, 74 bearing rollers, 2 thrust washers, 1 spacer,1 bushing, and 2 snap rings off the shaft. All the bearings look fine and it was a good thing because their not supplied with the kit.





All packed and ready to install on the shaft.







This is a massive countershaft




Next is the dismantling of the mainshaft to be replaced with the AA shaft.



After removing the front snap ring you need to be careful not to let the clutch sleeve slide off the clutch hub. Inside the clutch hub are springs, shift plates, and lock balls that will come flying out with force. Eye protection is a must. The best way to remove the clutch sleeve is to wrap a towel around it to contain the small parts.

There are two clutch hubs, (from left to right) item number 2 and 4.



Mainshaft and replacement, note the shoulder on the new shaft. One snap ring and one thrust washer will be omitted on the new shaft.



New shaft assembled minus the thrust washer and snap ring.



I drilled and tapped the lock plate using a 1/4 bolt cut to size.

 

[Posi]

I packed the 22 roller bearings in the clutch shaft then put it through the front bearing bore from inside the case. Then I dropped the rear end of the mainshaft assembly through the bearing bore at the rear of the case (won’t drop straight in). I installed the snap rings on both bearing and used a pipe and soft plow hammer to install the bearings. Make sure you tap on the inner part of the bearing and not the outer.


To keep the 22 roller bearings in place I used a piece of wood at the end of the shaft and tapped on the bearings.





Complete






Hope this helps