Eaton ELocker4 Differential Dana 44 Front 30 Spline 3.73 & Down Ratio

A classic Dana 44 with an open carrier is a strong axle with one big weakness: lift a tire or hit mud and all the power goes to the wheel that is spinning. The Eaton ELocker4 19977-010 is a selectable electric locker for 30-spline Dana 44 axles in the 3.73 and numerically lower carrier series. Owners of Jeep CJ, YJ, TJ and JK Wranglers, plus older Ford, Chevy and Dodge 4x4s with a 30-spline Dana 44, use it to get a full locker without giving up normal street manners.

What the ELocker4 does in a Dana 44

Unlocked, the ELocker4 is a plain open differential, so the axle drives, turns and wears tires like stock. Flip the switch and a 12 volt coil engages the locking mechanism, fixing the side gear to the case so both axle shafts turn at the same speed. The 4 in the name means four spider pinions instead of two, which spreads the load across more gear teeth. The case carries an 8.5 inch ring gear and is double drilled for 7/16 inch and 1/2 inch ring gear bolts, so it accepts either bolt size.

Symptoms this solves

• One wheel on the Dana 44 spinning while the other sits still in mud, snow, sand or on ledges
• A worn factory carrier with chipped spider gears, a loose cross shaft or clunks on and off throttle
• A tired clutch-type limited slip that no longer locks up or chatters in turns
• An automatic locker that is too harsh for a daily-driven Jeep and pushes in tight turns

How to confirm the carrier series

Dana 44 carriers come in two sizes depending on gear ratio, and this one is for the 3.73 and numerically lower series. Count driveshaft turns against tire turns or read the ring gear tag. If a standard Dana 44 has 3.92 or deeper gears, the correct unit is the ELocker4 for 3.92 and up ratios. The 2007-2018 JK rear Dana 44 is the exception: its thick ring gears use the 3.73 and down carrier even when the gear ratio is deeper, so this unit is the one for JK rear regears such as the JK Dana 44 rear 4.56 ring and pinion. Also count the shaft splines; this case is 30 spline with a 1.31 inch shaft.

Fitment

Eaton dealers list 19977-010 for 1970-2018 Jeep CJ, YJ, TJ and JK Dana 44 axles, front or rear, with 30-spline shafts and 3.73 and numerically lower gearing. Although the listing title says front, the same carrier is used in rear Dana 44s, and the JK non-Rubicon rear is the most common application. It does not fit the reverse-rotation front Dana 44 under the 2007-2018 JK Rubicon. Many Jeeps also run swapped or regeared axles, so check the axle tag, ratio and spline count, or send us the year and VIN. More drivetrain parts are on our hard parts page.

Install notes

• Remove the axle shafts, mark the bearing caps and pull the old carrier. A Dana 44 clamshell carrier bearing puller removes the old bearings without damage.
• Install new carrier bearings, then set preload with shims; a Dana 44 carrier shim driver seats the outer shims without chewing them up.
• Torque the ring gear bolts with thread locker, then confirm backlash and contact pattern.
• Follow the Eaton instructions for the coil wire pass-through; some housings need a hole drilled for the bulkhead fitting. Route the harness clear of the exhaust and steering.
• Fill with a quality petroleum GL-5 gear oil; synthetic is fine where the axle maker allows. No friction modifier is required.
• Engage at a stop or crawling speed with both wheels turning nearly together, and run unlocked on pavement, especially in a front axle.

Is 19977-010 only for front axles?

No. Despite the front wording in the title, Eaton dealers list it for Dana 44 front or rear axles with 30-spline shafts and 3.73 and lower gears, and it is a popular JK rear upgrade.

My JK rear has 4.88 gears. Do I need the 3.92-up version?

No. The 2007-2018 JK rear Dana 44 uses thick ring gears that fit the 3.73 and down carrier, so this unit is the correct choice for JK rear regears.

Will it fit the front axle of my JK Rubicon?

No. The 2007-2018 JK Rubicon front Dana 44 is not listed for this unit. Rubicons also have factory lockers.

What ring gear bolts does it take?

The case is double drilled for both 7/16 inch and 1/2 inch ring gear bolts, so it matches either size used on Dana 44 gear sets.

What else should I buy with it?

New carrier bearings and setup shims, ring gear bolts, gear oil, and a ring and pinion if you are regearing. Bearings are not included.