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Pros & Cons of Different Differentials - Making Traction

Posted in Product Reviews on April 23, 2015
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One of the most significant performance modifications you can make to a 4x4 to increase off-road prowess is the addition of a traction-adding device. Or better yet, two. Traction-adding devices replace the open differentials in your axles and help you get power to the ground, regardless of if one tire is dangling in the air or hopelessly spinning in the muck. Every traction-adding device has pros and cons, and determining which one will work best for you will depend on how you use your 4x4 and what compromises you are willing to make. We’ve compiled the most common 4x4 differentials to help you decide.

ARB Air Locker
The ARB Air Locker (arbusa.com) is an air-actuated selectable locker. When unlocked, it performs the same as a factory open differential. When locked, it provides 100 percent of the torque to both wheels. It is arguably the strongest aftermarket differential available. Engagement is quick and easy with the flip of a switch. However, poor installations can lead to leaky seals and damaged air lines. Contaminated oil can also cause the Air Locker’s internal seals to fail, requiring complete disassembly of the differential for repair. If air is leaking fast enough, the unit will not engage.

Pros
Strongest aftermarket differential available
No handling quirks on-road, spool-like traction off-road

Cons
Poor installation can lead to air leaks
Pump and wiring need to be purchased separately and adapted to the vehicle

Drop-in Lockers
The Auburn Gear Max Lock (auburngear.com), Powertrax (powertrax.com) Lock-Right and No-Slip, Torq-Masters (aussielocker.com) Aussie Locker, and the USA Standard Gear (spartanlocker.com) Spartan Locker are all automatic lockers that drop into your factory open differential carrier. They are sometimes called lunchbox lockers. The lockers perform similar to a Detroit Locker both on- and off-road. The drop-in design allows them to be more affordable than a full-case locker and easier to install. Most installations do not require disassembling the differential or resetting the gear backlash. However, they are significantly weaker because they depend on the factory case and cross pin.

Pros
Inexpensive
Easy to install and remove

Cons
Quirky handing on-road
Only as strong as the stock carrier and cross pin

Auburn Gear ECTED Max
The Auburn Gear (auburngear.com) ECTED Max is a cone-type clutch limited-slip differential that locks up to provide 100 percent torque transfer to both tires when you supply 12V power via a switch in the dash. The locker engages faster than other selectable lockers due to its design. We found that in most cases, the limited slip is aggressive enough that you don’t need to engage the locker. When new, you may notice some chatter from the limited slip when cornering on the street. The unit requires a friction modifier additive in the oil, and the clutch inside the differential is designed to wear over time. Unfortunately, you cannot service the clutches at home, the ECTED Max is not rebuildable. The differential can be shipped to Auburn under the D-Rex program for a replacement.

Pros
Very aggressive limited slip
Quick spool-like traction when locked

Cons
Clutch can wear out over time Not rebuildable

Eaton Detroit Locker
The Eaton (eaton.com) Detroit Locker is a mechanical full-case locking differential that engages both wheels whenever torque is applied. It will only unlock when it senses one wheel is spinning faster than the other, such as when cornering. It can be a handful when used on the street, especially in light weight, short-wheelbase vehicles with soft suspension, a lot of horsepower, and a manual transmission. If you break an axleshaft, it’s common for the teeth in the locker to shear off too.

Pros
No frills, simple automatic locking differential
100 percent traction to both tires

Cons
Quirky handing on-road
Locker can chuck teeth if you break an axleshaft

Eaton G80 Gov-Loc
The Eaton (eaton.com) G80, also known as the Gov-Loc is a true automatic locker, not a limited-slip differential. It has been an available option on GM trucks for decades. The unit automatically engages when the speed difference between the two tires on the same axle reaches 100 rpm. In a stock application, the operation is a little jerky. However, in an abusive or lifted application with bigger tires, the Gov-Loc often explodes as it engages.

Pros
True automatic locker
Optional on some factory GM applications

Cons
Jerking operation
Explodes when mixed with abuse and larger tires

Eaton ELocker
The Eaton (eaton.com) ELocker is a selectable locker that is activated via a 12V wire. When unlocked, it’s an open differential. When locked, it sort of acts like a spool. When you change directions (forward/reverse) the unit unlocks and then locks again. This could be a problem for those who need to rock the vehicle in Drive and Reverse to get unstuck. The newer versions of the Eaton ELocker feature four differential gears instead of two, making it significantly stronger.

Pros
No on-road side effects Engages quickly

Cons
Automatically disengages and reengages when you change direction
Included wiring, relay, and switch need to be adapted to the vehicle

Eaton Truetrac
The Eaton (eaton.com) Truetrac is a gear-driven limited-slip differential. It generally provides better traction to both wheels than most clutch-type limited slips. There are no clutches inside the Truetrac to wear out, and there is no need to use any special friction modifiers in the gear oil. The small multi-gear design makes it somewhat susceptible to damage from off-road bouncing and other abuses, but for general off-roading the Truetrac is a great limited-slip differential that can be used in the front and rear axles with very little on-road side effects.

Pros
Long-lasting limited-slip differential
No handling issues on-road

Cons
Not as brutally durable as other differentials
Will not provide 100 percent torque to both tires

Factory Limited-Slip
A factory limited-slip differential provides a greater torque bias and therefore offers more traction potential than a standard open differential. There are several different types of factory limited slips. However, most of them are designed to work seamlessly on the street, making them less useful off-road. Several OE off-road packages include a limited-slip rear differential. Only a handful are available with an optional limited-slip front differential. Most of the OE limited slips use clutches to create the torque bias, and often the clutches typically wear out long before the rest of the vehicle does. Most OE limited slips can be rebuilt at home to work like new again.

Pros
Near seamless on the street Comes stock in some 4x4s

Cons
Not much better than an open differential in most cases
Some clutch-type limited slips can wear out in 15,000-30,000 miles

Mini-Spool
A mini spool replaces the differential gears in a stock open differential carrier, providing full spool performance without the expense or hassle of disassembling the axle and resetting the gear backlash. The mini spool is only as strong as the factory open carrier and cross pin. Many different companies such as G2 Axle & Gear (g2axle.com), Moser Engineering (moserengineering.com), Motive Gear (motivegear.com), Richmond Gear (richmondgear.com), Summit Racing (summitracing.com), and Yukon Gear & Axle (yukongear.com) offer mini spools that bolt into the more commonly used 4x4 axlehousings.

Pros
Inexpensive
Easy to install and remove

Cons
Only as strong as the stock carrier and cross pin
Generally not streetworthy

Full Spool
A full spool provides 100 percent of the available torque to the both tires no matter what. The axleshafts remain locked together the entire time. Spools are generally reserved for off-road-only 4x4s and should almost never be used in a front axle. Using a spool in a front axle application will increase steering effort and limit your turning radius. Using a spool in the rear axle on the street will generally cause fewer handling quirks than an automatic locker like a Detroit, but the tire scrub will significantly increase tire wear. Many different companies such as G2 Axle & Gear (g2axle.com), Moser Engineering (moserengineering.com), Motive Gear (motivegear.com), Richmond Gear (richmondgear.com), Spicer Parts (spicerparts.com), Strange Engineering (strangeengineering.net), Summit Racing (summitracing.com), Trail-Gear (trail-gear.com), and Yukon Gear & Axle (yukongear.com) offer full spools that bolt into the more commonly used 4x4 axlehousings.

Pros
Inexpensive positive traction
Simple and strong

Cons
Generally not streetworthy
Not good for a front axle application except in straight-line competition like mud drags

Jeep Rubicon Lockers
Functionally, there have been three different Jeep (mopar.com) Tru-Lok lockers. The TJ Rubicon came with a low-pressure air-actuated limited slip/locker in the rear and a low-pressure air-actuated locker in the front. Both front and rear JK Rubicon differentials are electric selectable lockers. Aside from the TJ rear locker/limited slip, when off, they are open differentials. When switched on, they perform like spools and allow 100 percent of the available torque to reach the tires. The TJ Rubicon rear locker is a real prize that works as a limited-slip when disengaged. All of these lockers are expensive units and are difficult, if not nearly impossible, to install outside of their factory applications. The JK lockers are often slow to engage and disengage. You’ll see the best life expectancy from the Rubicon lockers if you limit tire size to a maximum of 35 inches in diameter.

Pros
First true OE selectable lockers
Seamless performance on the street with spool-like traction off-road

Cons
Limited applications
Slow to engage and disengage

G2 Axle & Gear Core Locker
The G2 (g2axle.com) Core Locker is an air-actuated selectable locker. However, it can be manually engaged and disengaged at the differential cover if there is a problem with the air system. When locked, the unit provides 100 percent of the torque to both tires. When unlocked, it works like a standard open differential. The air actuator is housed in the included beefy aluminum differential cover so it is easily accessed and rebuilt in the event a seal fails.

Pros
No handling quirks on-road, spool-like traction off-road
Can be manually locked and unlocked if air system fails

Cons
Limited applications
Pump, hoses, switch, and wiring need to be purchased separately and adapted to the vehicle

OX Locker
The OX Locker (ox-usa.com) is a selectable locker that can be engaged by a heavy-duty cable, onboard air pressure, CO2, 12 V, or manually at the cover. When engaged, the OX locker provides 100 percent of the available torque to both tires. When unlocked, it works like a standard factory open differential with no handling quirks. The OX locker comes with a heavy-duty ductile iron differential cover.

Pros
Lots of engagement options
Includes beefy differential cover

Cons
Limited axle applications
Engagement method of choice needs to be adapted to the vehicle

Open Differential
An open differential is typically the standard offering for most 4x4s from the factory. Open differentials are seamless on the street but almost worthless when traversing any type moderately difficult off-road terrain. Anyone that’s ever been stuck in the mud with catty-corner tires spinning uselessly knows how well an open differential works off-road. An open differential is not a good choice if you frequent areas with staggered holes, jumbled rocks, or slick surfaces. If abused, the thrust washers can wear out and the teeth on the differential gears can break off and bounce around inside the axle, often destroying other internal parts.

Pros
Seamless street performance
Comes stock in most 4x4s

Cons
Poor off-road performance
Not particularly strong

Welded Differential
A welded differential, sometimes called a Lincoln locker (because of the Lincoln welder company name), provides the same traction characteristics as a full spool. Welded diffs are generally not a good choice for street use and certainly not for a front axle. Like a spool, a welded diff will increase steering effort and increase the turning circle of your 4x4 when used in a frontend. If you have a welded differential, you should inspect it regularly. It’s not uncommon for the welds, carrier, or differential gears to crack.

Pros
Least expensive traction-adding device available
Can be applied to even the most obscure axles

Cons
Only as strong as the welds and stock carrier
Generally not streetworthy

Yukon Gear & Axle Zip Locker
The Yukon Gear & Axle (yukongear.com) Zip Locker is an air-operated selectable locker. When engaged, the Zip Locker provides 100 percent of the available torque to both tires. When unlocked, it works like a standard factory open differential with no handling quirks. Its design is similar to the older ARB Air Locker design and functions similarly. However, it is considered to be slightly weaker than the ARB. The forged case has been known to crack under extreme abuse. It’s said that this is designed into the unit on purpose to keep the axleshafts from failing.

Pros
No handling quirks on-road
Spool-like traction off-road

Cons
Considered weaker than other air-operated lockers
Pump, hoses, switch, and wiring need to be adapted to the vehicle

Yukon Gear & Axle Grizzly Locker
The Yukon Gear & Axle (yukongear.com) Grizzly Locker is an automatic locking differential. It functions very much like a Detroit Locker, which it is essentially a copy of. However, it is generally considered to be weaker than the Detroit. We have seen some abusive tall-tire applications spit Grizzly Locker teeth.

Pros
No frills, simple automatic locking differential
100 percent traction to both tires

Cons
Quirky handing on-road
Locker can chuck teeth in abusive tall-tire applications

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