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Cherokee XJ Drive Shaft Install

This Writeup is Under Construction

I needed two new drive shafts made because of the Klune-V installation. The front shaft needed to be longer, and the rear shorter. Plus, I converted the rear from a standard u-joint shaft to a CV (double cardan) style shaft because of the JB Conversions short shaft kit (SYE).

Rear Drive Shaft Conversion

Notice the "old vs. new" image, which compares the old drive shafts (top and bottom) to the new shafts (middle two). The top shaft is the old rear shaft. You can see that there are two main differences between it and the new rear shaft (the short, fat one just below). First is the "slip" portion of the shaft... that portion of the shaft that allows it to adjust to different lengths as the suspension works. The old design works with the stock NP231 transfer case and the slip is between the t-case and the shaft. This design is problematic because it is both weak and such that, if either side breaks, the t-case fluid is lost. There's a solution for this weakness that fixes it and another problem at once. In the rear shaft installed image, you'll see the JB Conversions short shaft kit installed on the back of the transfer case. This so-called "slip yoke eliminator" (SYE), converts the output from the slip-style to a standard yoke-style. I say "so-called" because the slip really isn't eliminated... it's simply moved to another location, to the more common middle of the shaft.

The second problem solved by switching to a standard yoke output is that the shaft is converted from a simple u-joint design (one u-joint at each end of the shaft) to a double cardan joint (also, incorrectly, called a CV joint). The double cardan, two u-joints at one end connected by a centering mechanism, allows for greater driveline angles with less vibration. The taller the lift, the more this conversion is helpful... even required. With a stock single u-joing design, the transfer case output and rear pinion angles must match to cancel vibration forces. The double cardan style drive shaft allows the pinion to point directly (zero angle) at the transfer case output, lessening the angle and reducing forces which could break the joint.

Where to Buy

There are many competent driveline shops around the country, and I try to maintain and use the specialty shops around my town. Many off-roaders prefer, however, to buy their drivelines from nation-wide manufacturers, like Tom Wood's Drive Shafts and South Bay Driveline. There's a big advantage with buying from either Tom or Steve (respectively) and that's their incredible service. They will make and ship a driveline the same day you order it, so no matter where you are (say, you've got a broken shaft somewhere in Utah), they can get you a new one the next day. Both shops make an excellent product, but there are some differences. Tom Wood uses a flexible boot to protect the slip joint. Not the wimpy kind you get with cheap shocks, but a truly heavy-duty boot that's water proof and tough. South Bay Driveline uses an OEM-style dust cover, complete with a grease fitting. Both styles are

South Bay Driveline - Steve
Tom Wood's Drive Shafts - Tom

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