Jeep Axle U-Bolt Yoke Upgrade

by Dan Barbieri

A weak link in many Wrangler, CJ-7, and CJ-5 drivelines can be easily eliminated by replacing the stock strap-and-bolt U-joint retainer system with a U-bolt setup. Often this upgrade can be performed by simply drilling out the existing threaded holes in the yoke to accept the new U-bolt. In cases where the yoke has insufficient room behind the yoke for the U-bolt nut, you can replace it with one designed for use with U-bolts. Please note that this is considerably more difficult, as it requires precise torque settings to properly set pinion bearing preload.

This article only covers the specifics for '80-'86 CJs and '87-'95 Wranglers. Earlier Jeeps typically use U-bolt yokes and information has not been gathered yet for '97+ Wranglers. This upgrade will also work for Cherokees and Grand Cherokees, but you must determine if you have a Dana 35c, Dana 44, or Chrysler rear end.

Dana 35C Rear Axle

Two pinion yokes were used on the YJ's D35C rear axle. Through 1993, Spicer part #2-4-6901-1X was utilized. This yoke uses 1310 series U-joints measuring 3 7/32" cap-to-cap. In 1994 and 1995, a larger pinion yoke part #2-4-7631-1 was employed which uses 1330 series U-joints measuring 3 5/8" cap-to-cap. Both of these yokes can be upgraded to a U- bolt setup by drilling out the existing holes with a 5/16" drill bit and installing U-bolt part #2-94-58X. You may find that a 21/64" drill bit is necessary, but the 5/16" did the trick for me.

Before	After

AMC Model 20 Rear Axle

The same trick can be performed on the AMC 20 pinion yoke part #2-4-3741-1. This yoke may be drilled out to accept U-bolt part #2-94-58X.

Dana 30 Front Axle (CJ)

Due to the number of different yokes installed on the D30, it's very difficult to state which yokes accept which type of conversion. Generally speaking, pre- and early-80s CJs already have U-bolt setups, while later Jeeps employed strap-and-bolt connections. For conversion from strap-and-bolt to U-bolts, you'll just have to eyeball it. If there is room for a nut behind the yoke, you can drill it. If not, you probably need to replace the yoke with Spicer part #2-4-8091X and use U-bolt part #2-94-28X.

Dana 30 Front Axle (YJ)

There is insufficient room behind the stock yoke for the U-bolt nut on the YJ front Dana 30 pinion yoke. The entire yoke must be replaced with Spicer yoke #2-4-8091X and U-bolt kit #2-94-28X to upgrade to a U-bolt connection.

Transfer Case Yokes

The NP231 front output yoke and both D300 output yokes do not have sufficient room behind the stock yoke for the U-bolt nut. Check out the article Jeep CJ Dana 300 Transfer Case U-Bolt Upgrade for a write up on the upgrade on the Dana 300. The front output on the NP231 uses the same parts and procedure as the Dana 300.

Contributor

Much thanks to Tom Wood at for the idea and the Spicer part numbers. Note the beautiful Six States heavy-duty CV driveshaft in one of the accompanying photos. I highly recommend them.

Last modified Wednesday, 01-Dec-2010 09:15:18 MST

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