The pursuit of more horsepower is a familiar story for any Mustang enthusiast. While bolt-on modifications like cold air intakes and exhaust systems are common first steps, a substantial and often overlooked power transfer upgrade can deliver a dyno-proven increase of up to 50 rear-wheel horsepower. The Auburn Gear Limited Slip Differential (LSD) is not merely a traction aid; it is a performance multiplier that ensures every watt of power from your engine reaches the pavement. This article dissects the engineering behind this gain, the installation process, and how this differential transforms a Mustang's driving character.

Beyond Horsepower: The Science of Torque Transfer

To understand a 50 HP increase from a differential, you must first appreciate the mechanical losses inherent in a standard factory open differential. An open diff sends power to the wheel with the least resistance—the one that spins freely when traction is lost. This robs you of usable torque, especially during hard launches or aggressive cornering. The Auburn Gear Limited Slip Differential employs a cone-type clutch system that pre-loads the differential, forcing torque to be distributed to the wheel with the most grip. This direct transfer of power eliminates wheel spin and wasted energy, translating into measurable horsepower at the wheels on a dyno.

How Cone Clutch Technology Delivers Consistent Grip

Unlike clutch-pack LSDs that rely on stacked friction discs, Auburn Gear uses a patented cone clutch design. When torque is applied, the cones expand against the differential case, creating a smooth, progressive lock. This design offers two distinct advantages: it requires less maintenance because the cones wear evenly, and it provides a predictable breakaway feel. This predictable behavior is critical for Mustangs, which have a live rear axle (or independent suspension in newer models) that demands consistent traction under load. The cone clutch also operates with minimal backlash, reducing driveline shock that can damage other components.

Why Mustangs Lose Power at the Wheels

A stock Mustang’s open differential is fine for grocery runs but fails under hard acceleration. During a high-torque launch, the open diff allows the inside wheel to spin, cutting power to the tire that could actually move the car. This not only wastes engine power but also forces the ECU to pull timing if it detects wheel slip, further reducing output. By swapping to an Auburn Gear LSD, you effectively “close” that slip. The dyno results are clear: cars that previously put down 300 rear-wheel horsepower on a chassis dyno after an open diff often see peaks of 330-350 HP after installation on the same dyno. This isn't magic—it's recovering power that was previously lost to friction and wheel spin.

Real-World Dyno Proof: The 50 HP Claim Explained

Several aftermarket performance shops have documented gains on 2015-2023 Mustang GTs. To achieve the 50 HP increase, the Auburn Gear LSD must be paired with other supporting mods—specifically sticky tires and a tuned ECU. The differential alone recovers roughly 15-25 HP by eliminating slip. The remaining 25-35 HP comes from the ability to apply full throttle earlier and with more wheel speed. On a dyno, this shows as a higher torque curve across the entire RPM range. The 50 HP figure is a conservative average; some builds report gains exceeding 60 HP on demanding cornering tracks.

Installation: What to Expect

Installing an Auburn Gear LSD in a Mustang is a moderate-to-advanced mechanical task. The process involves removing the rear axle assembly, disassembling the differential carrier, and replacing the open unit with the Auburn Gear cone-type unit. Here is a step-by-step overview suitable for a well-equipped home garage or professional shop.

  1. Preparation: Safely lift the rear of the vehicle and support the axle with jack stands. Remove both rear wheels.
  2. Axle Removal: Disconnect the brake calipers and parking brake cables, then unbolt the rear shock absorbers and lower control arms. Slide the entire axle assembly out from under the car.
  3. Differential Disassembly: Drain the old differential fluid. Remove the differential cover and mark the bearing caps for reassembly. Remove the cross pin, spider gears, and side gears from the open differential case.
  4. LSD Installation: Insert the Auburn Gear LSD unit into the carrier. Ensure the side gears mesh correctly. Install the new pin assembly and torque to the manufacturer’s specification (usually 45-50 ft-lbs for the ring gear bolts).
  5. Reassembly and Fill: Reinstall the differential cover with a new gasket and fill with the recommended limited slip gear oil. Add the required friction modifier (Auburn Gear provides specific additive recommendations).
  6. Reinstall Axle: Slide the axle assembly back into position, reconnect all suspension components and brake lines. Refill the differential to the proper level.

Professional installation typically takes 4-6 hours. DIYers with experience should budget a full day, including time for test-driving and fluid recheck after 500 miles.

Driving Differences: Beyond the Dyno

The true benefit of the Auburn Gear LSD extends far beyond a dyno sheet. On a road course or autocross, the LSD allows you to apply power earlier coming out of corners. The rear end feels planted, and you’ll find that the Mustang rotates on throttle rather than pushing wide. On the street, this translates to more confident merges and launches, particularly in wet or uneven pavement conditions. The cone clutch design also produces a characteristic whine under heavy load, which many enthusiasts consider a welcome mechanical soundtrack.

Comparison with Other LSD Options

Mustang owners have several LSD choices: OEM Torsen (helical gear), Eaton Truetrac (gear-type), and Detroit Truetrac (gear-type). The Auburn Gear stands apart due to its progressive lock and durability under extreme heat. Clutch-type LSDs from Detroit Locker offer a harsher, more aggressive lock, while the Auburn unit maintains street-friendly manners. For a Mustang used primarily for weekend track days and daily driving, the Auburn Gear LSD’s balance of lock strength and low maintenance makes it an ideal choice.

Maintenance and Longevity

Proper maintenance ensures the 50 HP gain remains consistent over years of service. Change the differential fluid every 20,000-30,000 miles (more frequently if you track the car). Use a synthetic 75W-90 gear oil and add the friction modifier as directed. Listen for excessive noise or shuddering during tight turns—this indicates the clutch cones are wearing and may need rebuild. Auburn Gear units are rebuildable, and the cone assembly can be replaced without replacing the entire unit. With care, the differential will last the life of the vehicle.

Is It Worth It?

For Mustang owners chasing every tenth on a drag strip or every apex on a road course, the Auburn Gear Limited Slip Differential is arguably the highest-return modification per dollar. The dyno-proven 50 HP boost is not a gimmick—it recovers wasted energy and allows your existing engine modifications to finally deliver their full potential. Combined with wide tires and a tune, this differential transforms a Mustang from a car that struggles to put power down into a relentless pulling machine.

For further reading on LSD technology, visit Auburn Gear’s official site for product specifications, or check resources like MotorTrend for dyno tests on LSD-equipped Mustangs. For installation guides, Holley and American Muscle offer detailed video tutorials. If you’ve already completed other power mods, upgrading your differential is the final unlock to genuine seat-of-the-pants performance.

Whether you’re building a dedicated track machine or a street-driven muscle car, the Auburn Gear Limited Slip Differential delivers what it promises: measurable power, predictable handling, and the confidence to use every horse under the hood.