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2007 Jeep Wrangler JK - CV Drive shaft Upgrades

Posted in How To on January 2, 2007
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Photographers: Jim Reel
The major difference between J.E. Reel's new driveshafts and the JK's factory driveshafts is the CV joints. J.E. Reel's 'shafts utilize U-joint technology, while the OE driveshafts use Rzeppa CV joints. The new driveshafts are constructed from 2.75x0.095-inch DOM (drawn-over-mandrel) steel tubing in the rear, and the front 'shafts are made from 2x0.0120-inch DOM steel tubing.

If you aren't familiar with your new Jeep JK's driveline system and would like to learn a little something about it, then please read on. The all-new Jeep Rubicon is an extremely capable off-road vehicle. Some people say it's even more capable than the TJ Rubicon in factory form, but as the old saying goes: Nothing is perfect. One of the very few mechanical issues the JK has is that Rzeppa CV (constant velocity) joints were used on the drivelines.

This joint was invented in the '20s by Alfred Rzeppa, a Ford Motor Company engineer. This style of CV joint was created for smooth vehicle operation and is more fitting for a car or luxury SUV. The major disadvantage of this type of CV joint is that it isn't designed to run at an increased operating angle. The result is that the joint's life is greatly reduced, and complete failure of it is quite possible under harsh conditions.

Like the Jeep Grand Cherokee and other Chrysler vehicles fitted with Rzeppa CV joints, if the vehicle is going to be left in factory form and driven mainly on the highway or used for mild wheeling then the OEM driveshafts should be just fine. If the vehicle is going to be modified with a suspension system that gives the Jeep an increase in ride height, then serious thought should be given to new drivelines.

The problem with the Rzeppa-style driveshafts is that they cannot stand up to the stresses of torque load at angles different from what the factory designed them for. This is especially true if the suspension is flexing and articulating off-highway. There is only about 3/4 inch of movement from the center of the Rzeppa joint (shaft) to the edge of its housing before the shaft makes contact. When the vehicle is lifted, articulated, and flexed, the shaft in the factory CV joint will make contact with the housing and start cutting into the retainer strap, rubber boots, and seals.

The Rzeppa CV joint comprises an outer housing, an inner race (multicross grooved or tracks), balls (large bearings), and a cage (bearing cage). The inner race is the center of the joint, the balls sit in grooves on the sides of the race, and these are held in place by the cage. All these components fit neatly inside the housing, but the balls of the joint are very close to the edge of the housing. If the vehicle hits a large bump or obstacle, or a wheel drops into a large hole, forcing suspension compression or droop, the balls can be forced out of the front or backside of the CV joint. This basically mean the joint has failed, leaving you stranded on the trail.

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J.E. Reel Drive Line Specialists has developed three new driveline systems for the '07 JK. All three series use a double Cardan-style U-joint at the output of the transfer case. Double Cardan CV joints alleviate any issues of extreme driveline angles. The 1310 series is a direct replacement of the factory drivelines and will bolt directly to the existing OE flanges for those who do not want to remove their transfer case and pinion yokes. The 1310-series CV drivelines come with pinion and transfer-case yokes that are more conventional with U-bolts and bolt mounting fasteners. The heavy-duty 1350-series comes with new flanges, yokes, and U-bolts for use under extreme conditions. Each driveline kit is manufactured using the highest-quality parts, the shafts are precision-balanced, and the flanges are CNC-machined for exacting tolerances.

These CV kits offer years of proven reliability under extremely harsh four-wheeling conditions. We fit our new JK with J.E. Reel's new heavy-duty series because of the extreme use this vehicle will see over time and because our previous experiences with J.E. Reel's products have been exceptional.

4x FactsLong wheelbase Jeep vehicles have always been popular with enthusiasts, but have been produced in limited numbers. The Jeep Scrambler (CJ8) was produced from 1981 to 1986. The Jeep Unlimited TJ (or pet name LJ) was produced for three years, from 2004 to 2006. The Rubicon version of the Unlimited was introduced in 2005. The massive 116-inch wheelbase Jeep Wrangler JK was introduced for 2007.

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J.E. Reel Drive Line Specialists

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