Transfer case swap

[Haas]

Bought a 78 CJ7 with a QuadraTrac Transfer Case . Did not know anything about the Transfer Case until after the purchase, my fault. Decided to go through the power train this winter, when we pulled the drain plug on the case a chunk of metal came out. We tore the Transfer Case apart and found the broken pieces, as you probably know we can't get the parts that we need and probably don't want them anyways.

I was thinking about the Dana 300 . I know I will have to swap the rear end to a center pumpkin style, but can I use the front axle and install locking hubs? It has AMC20 's front and rear. I also plan to upgrade the axle to the one piece design. I will need an adapter to go from the auto 400 Transmission to the Dana 300 and drive shafts. Am I missing any major components? Does anyone have a better suggestion? I know I could use the Dana 18, if I could find one, but I think now is the time to change.

Just looking for thoughts or suggestions. This is the first Jeep project.

Thanks in advance.

 

[GARGOYLEJEEPER]

You mean a Dana 20 offset, which would be the closest match and have the adapter to the 400, and keep your rear axle for when or if you get another QT.

 

[Posi]

The rig I just picked up has a 360, 400, D-18, and off-set rear 44 that out of a 79 Cherokee with a QT case. It has the #50-1300 adapter from AA that mates the 400 to either D-18/Dana 20 . Yes, on the hubs.

Side note: your rig has a Dana 30 front. I used to have a boat load of 18's, I still have a few, easier to find then you think. Lower geared then the 20 as well.

 

[Peanut Butter]

The two biggest hurtles for you will be the adapter between the Transmission and the Transfer Case , and the rear drive shaft. Adapters are expensive on top of buying another Transfer Case . Once you are pass the sticker shock, the choices are easy. An automatic Transmission in a Jeep CJ leaves little room for any other combination. The drive shaft angle and length will be the tuff to do without a custom drive shaft. Again just money.

I think the bigger question is what you intend on doing with your Jeep. Is it a daily driver, hard core 4x4, or will you do some mild 4 wheeling. This should drive you decision. There are people that will tell you the QuadraTrac is a good Transfer Case and you should stick with it. Others will tell you that you should never have bought one to start. I think more important you should pick a system tailored to what you plan on doing, then seek advice on how to proceed.

Finally, parts to the QT can be had. I have a QT in mine, but I've also bought 2 more of them to rebuild and use for parts. I paid $300 for those two and a GM Turbo 400 together.

Good luck with whatever you decide. Rod

 

[Saddle Tramp]

I’m not an automatic Transmission expert by any means but as others have stated if stock your automatic Transmission is also going to be an issue as the rear output shaft on it (GM Turbo 400 ) is too long for anything but a Qudratrac Transfer Case . Novak Adaptors and AA make an adaptor that includes a new shaft but they will lighten your wallet $400 to $600 give or take, and then the Transmission needs to be disassembled to install the shaft. If the Transmission is torn down to that extent you may as well just do a full rebuild.

Peanut Butter is on the mark about deciding just what the jeep is going to be, a daily driver or a trail rig or both as it may well guide your decisions. If wanting to keep the auto it is a matter of the expense of the adaptor and the rebuild or try to find another GM Turbo 400 that is already set up for either the Spicer 18 /Dana 20 or a Dana 300 . (Even then a rebuild may be in order.) The other option would be to convert to a manual Transmission in which case the swap could be done completely with OEM parts except for the drive shafts. (A CJ T-18 for example)

Whether you go auto or manual one option would be to go with a Spicer 18 Transfer Case (they are off set like the QuadraTrac ) as that would allow you to keep your offset rear-end. The 18 and 20 transfer cases (large hole) are the same case and interchangeable so they use the same adaptor. The latter years (large hole) Spicer 18s are strong cases and Herm the Overdrive Guy can make them almost bullet proof.

Let us know what you decide.

 

[Bent]

How about a Scout TF727 with the adapter for the Dana 20 but running a Dana 18 on it. That way you can keep the offset rear. Having both differentials in line gives you some ground clearance and a dropped rear output shaft like on the QuadraTrac and Dana 18 really improves your rear driveshaft angle. You can still get one piece shafts for the offset AMC20 . Converting to front locking hubs should be easy enough. Probably just swapping out a drive flange for a locking hub.