USA Standard Bearing Kit For Dana 30 JK Front

The USA Standard ZBKD30-JK is a front differential bearing kit for the Dana 30 under the 2007-2018 Jeep Wrangler JK, every trim except the Rubicon. If your JK has a front-end hum that changes with speed, a wet pinion seal, or the front axle is coming apart for a regear after a lift and bigger tires, this kit replaces the carrier and pinion bearings and the one-time install parts so the new setup starts on fresh hardware.

What the bearing kit does in a JK Dana 30 front

The JK front Dana 30 is a reverse-rotation (high pinion) axle: the pinion enters the housing above the axle centerline, which keeps the front driveshaft higher. Two tapered roller bearings hold the pinion in the housing with preload set by a crush sleeve, and two tapered side bearings carry the carrier and ring gear. Because the gear set is a reverse-cut design, it needs its own reverse-rotation gears, and bearing preload and backlash have to be right or it gets loud fast. Worn bearings let the pinion and ring gear move under load, which changes the contact pattern, produces whine and eventually damages the gear teeth.

The kit contains Koyo carrier bearings and races, Koyo pinion bearings and races, a pinion seal, pinion nut, crush sleeve, and gear marking compound with brush. Setup shims are not listed in the contents, so plan to reuse your original shims or have a shim assortment on hand.

Symptoms of worn front axle bearings

• Hum or whine from the front that rises with road speed, often heard in two-wheel drive because the front gears still spin with the axle shafts.
• A noise that changes when you get on and off the throttle in 4WD.
• Play at the front pinion yoke when you rock it by hand.
• Gear oil seeping from the pinion seal and slinging onto the front driveshaft.
• Metal on the drain plug or a gray, glittery fluid when the cover comes off.

How to confirm before buying

JK front-end noise is often blamed on the wrong part. Hub bearings and tires make a similar hum, so jack up the front, spin each wheel and rock the hubs before you open the axle. Our Dana 30 front axle problems guide covers the common JK failures, and the pinion bearing noise guide explains how to tell pinion bearing noise from gear whine. For JK drivetrain service intervals and the other components that get blamed for noise, see our Jeep Wrangler JK and JL service guide.

Fitment

Fits the front Dana 30 on 2007-2018 Jeep Wrangler JK and Wrangler Unlimited JK models, excluding Rubicon. JK Rubicons use a Dana 44 front and need a different kit. The JL Wrangler that replaced the JK uses a different front axle, so this kit does not fit a 2018 JL. If your JK has had an aftermarket axle swapped in, match the axle tag or the old bearing numbers before ordering, or send us your year and VIN and we will check it. More differential parts are in our rebuild kits section.

Install notes

• If you are regearing, see our JK regear kit buyers guide and order a reverse-rotation gear set such as the Revolution Gear JK Dana 30 4.56 ring and pinion. A standard-rotation Dana 30 gear set will not work in this axle.
• Pull the old carrier bearings with a clamshell puller like the Dana carrier and pinion bearing puller to avoid damaging the carrier journals.
• Set pinion depth and backlash, crush the new sleeve to the specified rotating torque, and check the pattern with the included marking compound. Revolution Gear lists 12-15 in-lb of pinion bearing preload and .006-.010 in. backlash as starting points for the Dana 30. Our backlash and pinion depth setup guide walks through reading the pattern.
• If you would rather not fight a crush sleeve, the JK Dana 30/44 crush sleeve eliminator replaces it with a solid spacer and shims.
• Fill with 75W-90 gear oil, then follow the new ring and pinion break-in procedure if the gears are new.

Does this fit a JK Rubicon?

No. Rubicon JKs have a Dana 44 front axle. This kit is for the Dana 30 front used on 2007-2018 Wrangler JK and Unlimited models other than the Rubicon.

Are shims included?

Shims are not listed in the kit contents. The kit has Koyo carrier and pinion bearings and races, pinion seal, pinion nut, crush sleeve and marking compound. Reuse your original shims as a starting point or buy a shim assortment if you are changing gears.

Do I need this kit when I regear my JK?

Yes, new bearings are strongly recommended with new gears. Pressing used bearings off and back on often damages them, and worn bearings will not hold the new setup. This kit covers the bearings and one-time install parts.

Will this fix a front-end hum on my JK?

Only if the hum is from the differential bearings. Hub bearings and aggressive tires make similar noise, so check for hub play and spin each wheel before opening the axle.

What fluid goes in the JK front Dana 30?

75W-90 gear oil. Check the fill level at the fill plug after the cover is installed and the sealant has cured.

• Jeep Wrangler JK and JL Transmission Service Guide