Lowering the Transfer Case on a Jeep Cherokee

Lowering the Transfer Case on a Jeep Cherokee

One common method to deal with drive shaft vibrations on a Lifted Jeep Cherokee is to lower the transfer case one inch to reduce the drive line angles. The pinion is rotated up slightly by using longer shackles or axle shims.

While there are various transfer case lowering kits available in the after market and even one from the Jeep dealer, they all serve the same function: they space the cross member down one inch from the unibody frame rail.

The spacers can be made in a variety of ways. On simple way is to take a piece of 1 inch square tubing or bar stock and drill two holes in it. Another method is to use a stack of washers or a piece of pipe cut one inch long and wrapped around each mounting bolt.

The original mounting bolts must be replaced with longer bolts and the two mounting studs must be removed from the frame. Normally these are replaced with bolts as well.

Bolting a dropped cross member into place can be a challenge. As the transmission engine unit drops it tends to move to the right. Without the studs to align the cross member, it is necessary to hold the cross member in place while starting the bolt into the threaded part of the frame. Because the bolt is now one inch longer, it is easy to cross thread it.

Also, since the cross member hangs down further below the Jeep it is easily impacted by rocks and other obstacles. It is possible to bend the nutsert in the frame making it even more difficult to get the bolts started once the cross member is removed for any reason.

One solution to the bolt problem is to make a longer stud instead of using four long bolts. This will help align the cross member when it is being installed and reduce the change of cross threading. If the nutserts are damaged, you may have to cut into the floor and install a bolt form the top of the frame. Alternately you can weld in a stud from below.

Another problem with the lowered cross member is the angle of the exhaust. The down pipe from the manifold is bolted to the cross member. As the cross member drops, the catalytic converter and the muffler will move down as well if nothing is done to compensate in the exhaust system. The pressure put on the hanger behind the muffler will exceed the strength of the rubber hanger. Also the increased pressure will cause the muffler to crack where the tail pipe exits over time unless the exhaust system is modified.

Having the transfer case sit lower also puts an extra strain on the transfer case shift linkage. If the transmission mount is worn the linkage can slip out of the body mount during off road flexing. When this occurs, the transfer case will not shift from 4wd to 2wd until the linkage is replaced in the bracket.

To eliminate the need to drop the transfer case, a Slip Yoke Eliminator kit is available for the transfer case and when used with a double cardon drive shaft, the transfer case can be used in its original position. See How to install a SYE for more information.

UPDATE: I noticed that the transmission mount for the five speed is about an inch thinner than the one for the automatic. I have not tried it yet but it looks like you could use a manual mount on an automatic to achieve a 1″ drop without lowering the cross member.

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