Eaton ELocker Installation On An Off-Road Ready Tundra

If you are like the majority of us, your off-road rig doubles as your primary daily driver vehicle. That means the ride is probably modified to make it more capable on the trail. At the same time, these modifications are limited in order to retain its street-worthy attitude. So, it is a fine line to maintain both on-road and off-road performance. Recently, we were tasked with identifying an off-road upgrade for Edgar Del Fierro (@BigFuun) and his 2015 Toyota Tundra which serves as his main set of wheels.

Being that this truck is mildly built and equipped for off-roading but also sees a lot of street miles, we determined the most appropriate solution was a Tundra ELocker installation. This electronically controlled locking differential from Eaton gives added off-road performance, through traction, on demand. Acting as the primary daily driver, it is important that the truck retains its street worthiness. When not engaged, the Eaton ELocker has no effect.

The Truck: 2015 Toyota Tundra Off-Road Capable Daily Driver

Edgar’s truck modifications started out with intentions to build a desirable platform to head out on weekend adventures. This typically means hitting up the local truck meets with the BVLT squad, driving the mountain trails, ripping the desert washes, and everything in between. Going out for a little off-roading, camping, and shooting is great fun. But venturing to very remote areas runs the risk of getting stuck and stranded, even in a 4×4. 

This concern prompted Edgar to look into various vehicle upgrades and off-road equipment. At some point, he added an ARB Air compressor that would allow for airing up tires after they had been aired down. And the typical traction boards were thrown in the back too.

As an avid off-roader, traversing various terrains means you have to be prepared. His equipment list currently includes an off-road-rated suspension system with King Shock Coilovers, front and rear bumpers, roof rack cargo tray, Toyo Tires, Method Race Wheels, so many Baja Designs LED lights, and the previously mentioned ARB on-board air system.

Edgar has his Tundra well-equipped currently and is still gathering parts for future front and rear long travel upgrades. These kinds of modifications are just enough to perhaps get Edgar into trouble when out off-roading. So back to the solution.

The Solution: Eaton ELocker

Off Road Xtreme has highlighted the Eaton ELocker before, specifically touching on the Toyota applications. However, we have never ran through a complete installation. Before we walk through that process, we should go over the features of an electronic locking differential. Simply put, this is the ideal solution for getting maximum traction to overcome challenging terrain.

Eaton describes their ELocker as an electronic selectable differential designed for drivers that need traction on-demand. Controlled by a manual electrical switch, once engaged the open differential is now transformed into a robust 100-percent-locked differential. A second flip of the switch deactivates the unit to resume normal driving. The ELocker is a reliable on-demand differential, featuring selectable operation and net-forged gears for added strength.

The four-pinion gear mechanism provides smooth engagement and consistent performance. Designed with outstanding strength of the net-forged gears, Eaton built this with durability in mind for years of reliable operation. 

Eaton ELocker Main Features:

  • Driver selectable operation – full axle lock upon activation
  • Net-forged gears for added strength
  • Works in forward and reverse
  • Front and rear axle applications

The Shop: Oceanside Driveline

Off Road Xtreme was referred to Oceanside Driveline by our colleague Vinny Costa from Street Muscle. They tapped the shop for a recent project and had a positive experience. Specializing in everything differential and driveline solutions, they offer sales, service, and installations. The business actually started off as Oceanside Brake & Driveline and has operated out of the same location for the last 32 years. Paul Hedrick and his wife took it over some time ago, and now they have become the region’s go-to source. 


Eaton ELocker Installation On An Off-Road Ready Tundra

Typical customers include the general public off the street, other car shops, municipalities, racers, and recreational auto enthusiasts. Oceanside Driveline serves the greater San Diego County, and Inland Empire areas. They are well known and have driveline components on high-performance race cars at the drag strip and in the desert, from Baja to Bonneville. There are six guys cranking away on driveline and differential projects including the owner Paul. Their little shop truck clocks over 35,000 miles annually running parts. 

The local racing clientele includes JD Fab, Hoffman Motorsports, Black Rhino UTV, Marc Burnett Motorsports, Matlock Racing, and many more. In fact, looking up at the wall amongst the framed pictures of racers, I immediately recognized most of them. My old friend Matt Torian in his 1450 Ford Ranger, who I supported through a FiberwerX sponsorship, was also prominently featured.

Out in the shop, various vehicles filled the bays and occupied the lifts. Two that caught my eye were a 1974 Toyota Land Cruiser FJ40 Diesel and an early 2000s Subaru Wagon lifted on 31-inch tires. There was also a totally bitchin raced-out Mustang.

The Tundra ELocker Installation Process

A Toyota Tundra, like most 1/2-ton pickup trucks from the era uses a live-axle rearend. What makes the Toyota different is the superior sized 10.5-inch ring-gear diameter. This is a big setup typically found in 1-ton trucks. Another plus is the drop out third-member which makes it easier to make gear changes and upgrades.

Below, we break down the steps of Toyota Tundra differential removal, disassembly, ELocker installation, reassembly, and reinstallation. For this project, we are only installing the Eaton ELocker. But if you are going down this road, it is the perfect opportunity to replace the ring and pinion, and make gear-ratio changes if needed. In this case we were re-using the original gears. Toyota’s OEM units are stout and there were zero reasons to replace these after only 150,000 miles.

Installation Summary 

  • Remove Tundra’s 10.5-inch third-member housing (drops out from the front)
  • Disassemble third-member and differential
  • Take off ring gear
  • Transfer over ELocker
  • Install pinion bearings
  • Drill out the third-member housing
  • Reinstall

Eaton ELocker Installation On An Off-Road Ready Tundra

Differential Removal Steps

  • Put the truck on the car lift
  • Remove rear tires
  • Drain oil from the rearend
  • Disconnect and secure the driveshaft so it does not hang loosely
  • Disconnect and free up brakes
  • Remove the axles
  • Unbolt the differential
  • Knock the case free using a dead blow hammer, and prying away from the housing seal
  • Remove and set aside third-member
  • Remove old seals and gaskets carefully sanding down hub flange, and diff mounting surfaces
  • Clean up and prep the rearend
  • Inspect for potential issues, excessive wear, metal debris, and any other problems
  • Spray down axle tubes inside and out to thoroughly clean up
  • Plunge tubes inside to remove any traces of oil
  • Rear axle housing prep is complete

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Differential Disassembly

For this project, we are reusing the existing ring and pinion gears. The techs confirmed everything inside the third-member did not have excessive wear and could be reused. The Eaton ELocker replaces the OEM differential. The ring gear is disassembled and separated from the carrier assembly and mated to the ELocker.

If we were going to re-gear the vehicle, this step would not be necessary as we would install a new ring and pinion alongside the ELocker.

Pro Tip: The carrier-bearing cups are marked to differentiate from side to side. This is done to ensure they are re-assembled back into position on the correct side from which they were removed.

  • Tech punches and marks case bearing mounts to distinguish driver side from passenger side
  • Bolts are pulled from bearing mounts and bearing mounts removed
  • Pull pinion nut
  • Pinion gear is punched out and removed
  • Remove pinion seals
  • Pinion race is punched out
  • All of the races and bearings will be replaced with a brand new master bearing kit
  • Any parts being reused are cleaned in the solvent tank and blown dry
  • Differential case gets coated with black engine enamel

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Eaton ELocker Installation On An Off-Road Ready Tundra

With everything fully disassembled it is now time put it back together with the new Eaton ELocker.

Differential Assembly Steps

  • With the ring gear bolts freshly cleaned, they need to be prepped for installation. 
  • Apply thread locker to ring gear bolts
  • Begin threading in the bolts to the ring gear
  • Flip over and hammer down on the ring gear to seat it down onto the Eaton ELocker carrier
  • Finish threading bolts down
  • Run the impact gun and torque down to manufacturer specifications
  • Apply anti-seize when pressing in side bearings
  • Press them into place

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Pinion Disassembly

  • Disassemble the pinion by pulling the bearing with a special puller tool
  • Any parts being reused are cleaned in the solvent tank and blown dry

Pinion And Pinion Bearing Assembly

  • Since there were no issues prior and there was no signs of extreme wear and tear, the old shim bearings are being re-used
  • Anti-seize is applied to each side and then placed into position on the new bearing
  • The bearing is pressed into place
  • More anti-seize is applied to the pinion housing
  • A small pinion race is pressed into the front pinion location
  • The differential case is flipped over and then the large pinion race is pressed into place

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Differential Housing Prep

  • The housing is drilled out and plumbed for the ELocker’s electronic wires. Make sure the wires has enough play and length
  • Eaton specifies no more than a half-inch hole to make sure there are no leaks
  • The differential housing mounting face is sanded down to remove any thread locker and gasket material
  • The housing is once again blown out w/ air to clean up any remaining debris 
  • The pinion seal is greased up


  • Put into place the pinion gear assembly inside the housing
  • Insert the small pinion bearing from outside with the pinion ring driveshaft flange put into place to help seat everything
  • Install pinion seal – Pro Tip: Apply silicone to pinion spline to prevent leaks
  • Apply anti-seize on bottom of nut and thread locker on pinion nut thread
  • Run the impact gun and torque down to manufacturer specifications
  • Sea the nut into the groove with a punch 
  • Put the assembled carrier and shims into position in the differential housing
  • Install the Eaton cage lock into place
  • Align the carrier-bearing cups to the same side as from which they were removed
  • Apply thread locker to bolts and run down with an impact gun
  • Paint the ring gear
  • Check and inspect for even wear pattern on the gear teeth
  • Run Eaton’s ELocker wire through the pre-drilled hole
  • Use silicone to make gasket on differential housing seat
  • Put assembled differential into place on rearend housing
  • Hammer assembled differential into place with dead blow
  • Secure into place with differential housing bolts
  • Run them down evenly with an impact gun
  • Install drain plug
  • Reinstall axles with new axle seals
  • Brakes and driveshaft are reinstalled
  • When the silicone gasket is cured, refill with appropriate differential gear oil as specified
  • Complete wiring of ELocker to electronic control switch inside for driver control

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Eaton ELocker Installation On An Off-Road Ready Tundra

As always, Off Road Xtreme recommends that every off-road rig undergoes thorough maintenance and regular inspections. If you are not performing these routines yourself, we advise to hit up your local vehicle driveline specialist for service and modifications. We want to thank Paul and Jeff from Oceanside Driveline for their assistance in this project. You can bet we will be regular customers for our future driveline needs. We also want to thank the technicians Eric Patton and David Bernall for thoroughly walking us through the entire process. 

Eaton ELocker Installation On An Off-Road Ready Tundra

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