Article Quick Jump To:

• Clocking The Transfer Case

• Transmission Crossmember

• Doubler Support Bracket

• Linkage

• Extending The Shifter Fork

• Speedometer Cable

• Driveshafts

• Wisdon To Share

From Kage:

This is my first foray into any transfer case. Thankfully it turns out that they’re quite a bit simpler than I thought they would be. I don’t know if the gear driven cases are any more complicated, but my guess is that they’re even simpler.

I’m using the D&D Machine kit from Duffy (he also makes the “Box For Rocks” kits for the Jeep stuff as well). The kit really is quite simple to put together (heck, even a goofball like me managed to get it done without too much of an issue). If you really had to hammer though it, you could probably knock this project out in a day easy (day + plus whatever time you need for the form-a-gasket to cure).

Duffy’s kit comes with the adapter plates, block off plates, all the bolts needed, shorter shift rail, and the all important splined shaft.

Once you have the kit, you’ll need a BW1354 (either an electric shift or manual shift will work as this is the rear case):

And also a BW1350 (Manual) case for the front:

Rear case portion of this is stupid simple to put together (BW1354 case). But before you can slap it together, you’ll need to do something about the breather as it will be in the way of the doubler adapter plate. Either drill and tap a new one, or make a 90° elbow work as I did.

Remove the stock breather and do a little clearance grinding on the case. Then grind your 90° elbow to allow it to spin onto the case, and stick your old breather vent into the 90° elbow to finish this part off.

Once that’s done, you get to move to the first portion of your doubler build. That being, slapping on the rear adapter plate. Don’t forget to seal it up!

You can either have these welded on, or just use some form-a-gasket to seal them off. I opted for the latter as this is just an Aluminum transfer case, I want to be able to pop these blocks off in the future if something were to happen the doubler case.

Once the blocks fit to your liking, its time to clean out the case and swap the shift rails out:

Seal up the adapter and block off plates, don’t forget to tighten up the screw for the new shift rail!:

After the sealant has set on the front case, slap some sealant on the surface between the adapter plates and screw them together. This is my only other complaint about this kit. Instead of having the shift rail screwed to the back side of the adapter plate (another place to possibly leak). It would have been nice to have the rail ‘float’ instead which would allow you to pull the shift fork out while tightening down these screws. 

Getting under the shift fork is a pain for folks with big hands! 

TIP: Drill a hole in the shift fork to allow you to get to the allen bolt underneath it (I forgot to do that, it would have made life easy). This is also the point in which you get to clock the rear case.

Plop the shaft in and slide the planetary set back into the front of the case (It helps to rotate it as you insert it). Don’t force it! It will slide in easily once everything lines up. Give everything a spin to makes sure it feels good while you’re at it. (And yes, you’re allowed to giggle as you make it spin in double low while its on the bench).

Now you just need to address the vent tube for the front case. In the latest revision of this kit, Duffy put a tapped hole on the adapter plate to be used for a vent. Since that hole sits higher than the stock vent, it’s wise to just plug up the stock vent tube hole:

For the Main vents, I made them “T” into each other to less the amount of lines running around under my truck. At this point I think I’m going to run the vent line out back behind the cab, but that’s subject to change once I get the doubler under the truck.:

Fill it up with fluid (about 3/4 of a quart) and slap it in the truck (I don’t have it in my truck yet so no pics). It looks like I’m going to get lucky with the linkage as my case came with the 1350 linkage for the AL4D. So it should work with my M5OD tranny and make life simple. If not, I’ll make it work.

As a side note, when looking at the guts of the 1350 and the diagram of the 1354E. I’m thinking it might be possible to take the mechanical linkage out of a 1350 and make it work in the 1354E case to lose the electric shift motor. If I come across a couple of cheap cases in the future, I might have to give this a try.

As another side note, If you have a spare 1354 laying around, you can pull the Planetary, shift fork, and slide gear to upgrade form the 4 gear set to the 6 gear set (1993+ 1354’s). I didn’t have that luxury, so I’ll just rock the 4 gear set. If it breaks, I’ll worry about it then.

Edit: The doubler add 6.75" to your driveline

Clocking The Transfer Case:

The following photos show the differences between the cases clocked together in a stock position, and then clocked by (1) bolt hole.

The Cherokee drive shafts are 1.75-inches on the ID, and they are made with 0.120-inch wall HREW tube. Since its HREW, you can’t just slap a slug in there and call it done.

Step 2 - Find some “Plug” material and mill (grind with a grinder) a couple of slots to clear the weld slag inside the tube. I’ve got an extra 1-inch that was driven into either side of the DS (I needed to extend the shaft 6.75-inches and my plug was 8.75-inches long, dig?). The extra bonus of the slots is that it makes it easier to keep the two ends of the drive shafts even:

Step 4 - Step 4 is a little tricky. I don’t have a good way to hold everything in line, so I bolted the DS back in its home to check for the correct length. While it was there, I slapped a dial indicator on it to rotate and tap in line. This is far from ideal so I’m not so sure on how accurate my 0.020” run out reading really was. But as I said, worse case is I just have a spare shaft now. Add to it, I can’t really remember if this was a good shaft to start with so who knows how good it is at this point

Step 5 - Remove the now tacked together DS from the truck and burn everything home, clean off your slag and you’re done!

Wisdon To Share From the discussion 'Building a 1350/1354 doubler- any wisdom to share?':

Alignment: 

Make sure the two cases are perfectly aligned with each other so the shaft doesn't fatigue and break prematurely. Make sure it shifts correctly and holds in gear/position.

Planetary gear & Shift Fork (By slammer67): 

Basically my problem was the shifting setup on the BW1350. There was too much play in the shift fork/planetary, and the plastic shift guides would wear down fast causing the doubler to pop out of gear. It left me stranded twice. I started researching and found that you could use the planetary gear and shift fork setup out of the BW1354 in the BW1350.

I haven't had any more problems since I switched to the BW1354 shift setup. You can use a BW1354 for the doubler, it's the same setup, but finding a BW1354 manual might be frustrating. You can get a BW1350 manual and an electronic shift BW1354 to rob the planetary and shift setup. 1993 and later BW1354's have 6-gear planetaries vs 4-gear for the earlier ones. I would suggest switching to the later shift setup. I think my problem came from a leak in the doubler. I didn't watch it closely enough and the fluid got low and it overheated - which is probably where the excessive wear in my shift fork and planetary came from.

Leaks (By slammer67): 

Be careful when you cut the case and weld on a block plate. I think that was one of my leakage problems. I left a small gap that the sealant didn't fill too well. Some JB Weld and careful filing solved that. I don't seem to have leaks now, and it's been a good 6 months since I've messed with it.

Breather (By Bray D):

I relocated the breather hose to the top of the case, and used the old breather location as a filler hole. This raises the fluid level in the case by a substantial amount. Problem is, it burps fluid out the top of the case, through the relocated breather hose. I've got the case out now (replacing slave cyl in trans), and am having a guy weld a baffle inside the case to hopefully prevent the fluid from getting into the breather hose.

Helpful Discussion In Our Forum:

Kage's Build Thread - The Lone Ranger – Kage’s ’94 X-Cab Leaf SAS and Bed Bob

Bray D's Build Thread - Daily Doubler Build

Wisdom To Share - Building a 1350/1354 Doubler- Any Wisdom To Share?