The Wrangler YJ was produced with two different axles: the Dana 30 front and the Dana 35 rear.
The YJ Dana 30 came with new innovations that had never been seen on a Jeep nor any Dana 30 axle used on any make of vehicle. It made use of a reverse-cut ring and pinion. Up until this time, the Dana 30 (which was introduced to Jeep vehicles beginning in 1972) had used a standard-cut ring and pinion. The advantages of a reverse-cut ring and pinion is that they are stronger when used in front axles, and also provide better ground clearance and driveline angles. The YJ Dana 30 also made use of a vacuum-actuated central axle disconnect in lieu of manual locking hubs. The Dana 30 in Wranglers equipped with 4-cylinder engines had a 4.10 gear ratio (41 teeth on the ring; 10 teeth on the pinion). The Dana 30 in Wranglers equipped with 6-cylinder engines had a 3.07 gear ratio (43 teeth on the ring; 14 teeth on the pinion).
The YJ Dana 35 was an adequate axle if the Wrangler was left completely stock without any off-road upgrades. The Dana 35 is unpopular due to its inability to handle larger tires, bigger engines, or low ratio transfer cases. It has a weak housing that has been known to flex and shafts that have been known to break when put under the stress of off-roading. Depending on what type of off-roading is done and the size of tire involved, some Wrangler owners have broken this axle with 31" tires, while other have been able to handle 35" tires. Because axle swaps can be expensive and require special tools and lots of research, many third-party companies have produced "Super 35" kits that replace the Dana 35 parts with components made of stronger materials that are more capable of handling the abuses of off-roading. The Dana 35 in Wranglers equipped with 4-cylinder engines had a 4.11 gear ratio (37 teeth on the ring; 9 teeth on the pinion). The Dana 35 in Wranglers equipped with 6-cylinder engines had a 3.08 gear ratio (37 teeth on the ring; 12 teeth on the pinion).
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