Jeep Wrangler Transfer Cases and Drops: Essential Guide

Before modifying any part of a vehicle, you need to get yourself to a good starting point. If you’re building a Jeep TJ or YJ, you’re talking about a vehicle that’s been on the road for over ten years at least. It’s a good idea to take a look at the transfer case and replace what needs to be repaired. This is a good time to make some modifications while you’re at it.

• Bearings: Transfer Cases work with moving parts. With that being said, bearings are a massive part of the operation of the unit. If you notice a roughness in the operation you may want to tear it down and have the bearings replaced. These parts don’t go bad often so if it’s not broke don’t fix it.
• Shift Forks: While running through the woods you’re going to shift into 4-wheel drive a lot. After a long period of time, the shift fork itself is going to need replacing. It’s a good idea to upgrade to a heavy-duty unit. Not only will this fix the problem, but it will stand up to the heavy abuse you throw at it from time to time. 
• Shift Linkage: If the shift fork is being replaced, it’s a good idea to replace the shift linkage while you’re at it. It is in the same line of fire, and it’s likely it’s about kicked as well. The same rule applies; heavy-duty replacements are available so you might as well make the upgrade. 
• Housing Rear Extension: If you’re finding an oil leak under the vehicle, the housing extension could probably be replaced. The last thing you want to do is run the unit dry and fry those bearings we talked about earlier. It’s a quick fix, and even if it isn’t completely shot, it’s nice to have the peace of mind that it’s in good shape. 

Lifting a Jeep Wrangler is one of the most logical things you can do in life. It’s second nature just like brushing your teeth; you’re going to lift your Jeep. Doing so changes more than the ride height, though. It can directly affect your vehicle’s driveline angles. This may not be a problem for lift kits under 4 inches, but anything above should be combined with this modification.  

Driveshafts connect the differentials to the transfer case. As the Jeep is lifted, the differentials will stay in place. Since the transfer case is attached to the body of the Jeep, the driveshafts will be put at a more extreme angle. Having an extreme angle on the driveshaft will cause a ton of vibration and can start to destroy things if it isn’t addressed.

Transfer case drops are the perfect solution to this issue. These kits consist of spacers and hardware extensions. They extend the distance between the transfer case and the factory mounting point, which in turn corrects the driveline angle. It is another step between you and going wheeling but this can be the difference between having a good day and massive frustrations.

If you are opting to drop the transfer case don’t forget to drop the linkage with it. The worst thing would be making this change only to find that your stock linkage will no longer be long enough. It’s only a few more nuts and bolts but it is an absolute must. 

For guys with a big lift kit, in the realm of 6 inches and higher, dropping the transfer case isn’t going to cut it. The problem is the driveshaft has become too short. With the slip yoke it may be able to slide into place making impressions that it will work, but you can learn some valuable lessons the hard way if you take it out wheelin’. 

A slip yoke is how the driveshaft attaches to the factory Jeep transfer case. It simply slides into place and isn’t secured with anything more than some splines on the output shaft. This is so as the suspension flexes the driveshaft can move freely, keeping it the right length at all times. 

When you have a really big lift kit, the distance between the differential and the transfer case is increased and though it may slide into place it can slip out on you when you’re out in the woods. When that happens, you will lose power to the rear wheels and lose a whole bunch of fluid. 

A slip yoke eliminator converts the transfer case to have a fixed mount for the driveshaft. The major benefit of this is the driveshaft can no longer slide around on you. Since these kits are meant to work with big lift kits, they are also designed to correct the driveline angle to make sure you’re not putting too much stress on your u-joints. 

You also may find the factory transfer case is prone to leaking. Since these kits are designed to replace the housing extension, potential leaking issues are greatly reduced. They are also extremely durable pieces and with all the added benefits it’s pretty much a no-brainer to make this upgrade. 

For JK owners, a new product from the company Teraflex is on the market: a 2Low kit. This is a pretty complex piece of equipment that changes the function of the transfer case greatly. Mainly, it’s designed to reduce steering bind when you’re out in tight trails. It may require professional installation and it changes the shift pattern of the transfer case. Once it's installed you will be able to select 2 low. This gives you the ability to turn freely with low range gearing.