Eaton Elocker4 Differential 27 Spline 3.54 Ratio Dana 30

The Eaton ELocker4 19817-020 is the electronic selectable locker for the 27-spline Dana 30 front axle in Jeep CJ, YJ, XJ Cherokee, TJ and non-Rubicon JK Wranglers that still run a numerically low gear ratio. If your Jeep lifts a front tire on a ledge and the spinning wheel takes all the torque while the other one sits still, this is the part that fixes it: flip the dash switch and both front wheels turn together; flip it off and the axle drives like an open differential on the street.

What the ELocker4 does in a Dana 30

A stock Dana 30 carrier is an open differential. Its spider gears let the two front wheels turn at different speeds in corners, which is good on pavement and useless when one tire is in the air. The ELocker replaces that carrier. Inside is a 4-pinion net-forged gear set (the "4" in ELocker4) instead of a lighter 2-pinion arrangement, plus an electromagnet. Energize the coil from the included rocker switch and the mechanism locks the side gears to the case, so both axle shafts receive the same torque, in forward and reverse. Eaton lists engagement at about 0.14 seconds for the direct-acting ELocker4. With the switch off, the unit behaves as an open diff, so steering and tire wear are not affected in daily driving.

Signs your Jeep needs this carrier (or that the old one is done)

• One front tire spins freely on off-camber climbs while the opposite tire does nothing
• Clunk from the front axle when switching between drive and reverse in 4WD, often worn spider gears or cross shaft
• Chipped spider gear teeth or metal flakes on the fill plug magnet at a fluid change
• An aftermarket locker that no longer engages, or a factory limited slip that has worn to open
• Ring and pinion whine that means the axle is coming apart anyway, which is the cheapest time to add a locker

How to confirm the right ELocker before ordering

The title says 3.54, but what matters is the carrier break. Dana 30 carriers come in two sizes: this one, 19817-020, is for ring and pinion ratios of 3.55 and numerically lower. Jeeps with 3.73 or higher gears, including most trucks that have been re-geared for larger tires, need the ELocker4 19818-020 for 3.73-and-up Dana 30s. Read the ratio off the axle tag or the ring gear, or divide ring gear teeth by pinion teeth. Then count the axle shaft splines: this unit is 27 spline. A Dana Super 30 with 30-spline shafts takes a different ELocker (19819-020). If you plan to re-gear soon, for example to a 4.88 Dana 30 ring and pinion for the TJ, buy the 3.73-and-up locker instead, because this carrier will not clear the larger pinion.

Fitment

• Dana 30 front axle, 27-spline inner axle shafts
• Ring and pinion ratios 3.55 and down
• Listed for 1971-2018 Jeep CJ, YJ, XJ, TJ and JK applications with a Dana 30 front
• Not for Rubicon models with a Dana 44 front, and not for JL/JT Dana 30 axles (use the 3.73-and-up unit)

High-pinion and low-pinion Dana 30s exist across these years, so match the axle you actually have rather than the model year alone. If you are unsure, send us your year, VIN and the ratio from your axle tag and we will confirm. Browse other carriers, axles and gear sets in our hard parts collection.

Install notes

• The ELocker needs its own carrier bearings; the installer note calls for carrier bearing kit CK3035, so do not plan on reusing the original cones
• Pull the carrier, press the ring gear onto the ELocker, and reset carrier bearing preload and backlash with shims, then check the contact pattern. A bearing separator and puller set makes removing the old cones far easier
• Route the coil lead out of the housing and seal it per Eaton's instructions, then wire the included switch and harness to a fused, switched 12V source
• Refill with a quality GL-5 rated petroleum gear oil; synthetics are acceptable if the axle maker calls for them
• If the axle is apart for gears too, a full JK Dana 30 front master install kit covers the pinion bearings, seal and crush sleeve

On the trail, engage the front locker at crawling speed and keep the wheel as straight as you can. A locked front axle resists turning, so switch it off once you are past the obstacle.

My Jeep has 4.10 gears. Will 19817-020 fit?

No. This ELocker4 is the 3.55-and-down carrier for the Dana 30. Ratios of 3.73 and higher use a different carrier size, which is the 19818-020 ELocker4. Check your axle tag or count the ring and pinion teeth before ordering.

Does it fit a Rubicon or a JL Wrangler?

TJ and JK Rubicons use a Dana 44 front, so this Dana 30 locker does not apply. The JL Dana 30 front is listed under the 3.73-and-up ELocker4, not this one. It is meant for 27-spline Dana 30 fronts in CJ, YJ, XJ, TJ and non-Rubicon JK Jeeps.

Are the switch and wiring included?

Yes. Eaton includes the locking rocker switch and the wiring harness. You still need to connect it to a fused, switched 12-volt source and route the coil lead out of the axle housing as Eaton describes.

Can I reuse my old carrier bearings?

Plan on new ones. The install note for this unit calls for a specific carrier bearing set (CK3035), and new cones and cups with fresh shims are the only way to set preload correctly on a new carrier.

What gear oil should go in after the install?

Eaton recommends a quality GL-5 rated petroleum (mineral) gear oil, and says synthetic can be used if the axle manufacturer recommends it. Use the viscosity your Jeep's owner manual lists for the front axle.

Will the front locker make my Jeep hard to drive on the street?

Not with the switch off. Unlocked, the ELocker acts like an open differential, so daily steering and tire wear stay normal. Only lock it when you are off-road at low speed.