Revolution Gear & Axle 07-18 Jeep Wrangler JK Dana 30 Front Koyo Ring & Pinion Master...

Owners of a 2007-2018 Jeep Wrangler JK Sport, Sahara or other non-Rubicon trim end up here for one of two reasons: they are regearing for 33 to 37 inch tires, or the front Dana 30 has started to whine and leak. Either way the front axle needs new bearings, shims and seals set up correctly. The Revolution Gear and Axle K35-2050 is the Koyo-bearing master install kit for the JK front Dana 30, and it is the box to order with new front gears.

What the master install kit does in a JK front Dana 30

The JK front Dana 30 is a high-pinion, reverse-rotation axle. The pinion sits above centerline to keep the front driveshaft up out of the rocks, and the gears are cut for that rotation. The pinion turns on two tapered bearings preloaded by a crush sleeve, and the carrier spins on two side bearings whose shims set backlash and bearing preload. Revolution lists the K35-2050 with Koyo pinion and carrier bearings, pinion seal, crush sleeve, pinion shims, carrier shims, ring gear bolts, cover gasket or silicone, and axle seals. The axle seals matter on a JK: the inner tube seals sit right where the shafts slide out, and once they are disturbed or worn, gear oil runs out toward the knuckles and ball joints.

Symptoms that call for front bearings or a full setup

• Front whine that rises and falls with throttle, often louder in 4WD
• Clunk or slack when you rock the front pinion yoke by hand
• Gear oil on the inside of the front wheels or at the knuckles from leaking inner seals
• A pinion seal that keeps leaking because the bearings let the yoke wobble
• Constant downshifts and weak highway pull after a tire upgrade on factory 3.21 or 3.73 gears

How to confirm before buying

First make sure the front axle is a Dana 30. Rubicon JKs have a Dana 44 front that takes a different kit, and many used Jeeps have had axles swapped, so read the tag on the housing. Then check yoke play, look for oil at the inner tube ends, and drain a little oil to look for glitter. Our Dana 30 front axle problems guide covers the noise and leak checks, and the JK regear kit buyer's guide lists what each axle needs.

Fitment

Revolution lists the K35-2050 for the Jeep Wrangler JK, 2007-2018, with the Dana 30 front axle differential. It does not fit the JK Rubicon Dana 44 front, either JK rear axle, or the 2018-up JL front: Revolution publishes a separate JL M186 row in its setup chart with different specs, so a JL needs its own kit. If you prefer Timken bearings, we also carry the Timken version of this JK Dana 30 kit, 35-2050; the Koyo kit is listed with the same list of included parts. Send us your year and VIN if you are not sure which axle you have.

Install notes

Gear sets for this axle must be reverse rotation, such as the Revolution JK Dana 30 4.56 reverse set or the 4.88 reverse set for 35s. Revolution lists a 3.55/3.73 carrier break for these gears, so a Jeep that left the factory with gears numerically lower than 3.73 will need a JK Dana 30 3.73-and-up carrier or a locker in that series. Revolution's D30JK row calls for a 0.065 inch starting pinion depth, 12-15 in-lb pinion bearing preload with new bearings, .006-.010 inch backlash, 55 or 75 ft-lb ring gear bolts depending on bolt size, and 60 ft-lb bearing caps. Preload on a small Dana 30 pinion is easy to overshoot with a crush sleeve, which is why some builders fit a JK front crush sleeve eliminator. Use our backlash and pinion depth guide to read the pattern, fill with 75W-90 gear oil, follow the break-in procedure, and update the tire size and axle ratio in the JK computer so the speedometer and shift points are right.

What is the difference between K35-2050 and 35-2050?

The K prefix is Revolution's Koyo bearing version. The 35-2050 uses Timken bearings. Both are listed for the 2007-2018 JK Dana 30 front with the same included parts.

Does this kit include axle seals?

Yes. Revolution lists axle seals as included, along with Koyo pinion and carrier bearings, pinion seal, crush sleeve, pinion and carrier shims, ring gear bolts and cover gasket or silicone.

Will it fit a JK Rubicon or a JL?

No. A JK Rubicon has a Dana 44 front, and the 2018-up JL non-Rubicon front Dana 30 (M186) uses different setup specs and its own bearing kit.

Do I need a new carrier to run 4.88 gears on my JK Sport?

If the Jeep came with 3.21 gears, yes. Revolution lists a 3.55/3.73 carrier break for these gears, so a 3.73-and-up carrier or locker is needed. A Jeep with factory 3.73 gears is already on that side of the break.

What gear oil goes in the JK front Dana 30?

75W-90 gear oil. After new gears, change it early once the break-in miles are done.

Is the ring and pinion included?

No. This is the bearing, seal and hardware kit. Order a reverse-rotation JK Dana 30 gear set separately in the same ratio as the rear axle.