2018-2022 BMW F90 M5 F91 F92 F93 M8 AWD X DRIVE REAR DIFFERENTIAL RATIO 3.15 OEM

The 2018-2022 BMW F90 M5 / F91 F92 F93 M8 AWD xDrive Rear Differential with a 3.15 final drive ratio is a key component in the drivetrain of these high-performance M models. This differential plays a significant role in how power is distributed to the wheels, ensuring optimal performance, handling, and traction under different driving conditions.

Key Information about the Rear Differential with 3.15 Ratio (OEM Spec):

Differential Type:

• Active M Differential:
  • This is an electronically controlled limited-slip differential, allowing for variable torque distribution between the two rear wheels.
  • It continuously monitors inputs like throttle, steering angle, and wheel speed to dynamically adjust power delivery, improving traction, handling, and cornering stability.
  • This system helps optimize performance in both high-speed cornering and during straight-line acceleration, offering better grip and control.

Final Drive Ratio: 3.15:1:

• The 3.15:1 final drive ratio is common for high-performance models like the BMW M5 and M8, balancing low-end torque for quick acceleration and reasonable engine speeds at higher velocities.
• This gear ratio provides an excellent mix of explosive power and the ability to cruise comfortably at higher speeds without over-revving the engine.

xDrive AWD System:

• M xDrive (All-Wheel Drive):
  • The M xDrive system in these BMW models is a rear-biased all-wheel-drive system, designed to give the driving dynamics of a rear-wheel-drive car with the added traction of AWD when necessary.
  • The driver can choose between different drive modes (4WD, 4WD Sport, and 2WD), allowing for various torque distributions depending on the driving scenario.
  1. 4WD Mode: Full all-wheel-drive functionality, ideal for traction in poor road conditions.
  2. 4WD Sport: Rear-biased power distribution for a sportier, more dynamic driving experience.
  3. 2WD Mode: Allows the car to operate in a pure rear-wheel-drive setup, giving a more traditional M experience with no AWD assistance.

Construction & Durability:

• Aluminum Casing:
  • The rear differential is housed in a lightweight aluminum casing, reducing unsprung weight and contributing to better handling dynamics.
• Heavy-Duty Components:
  • Designed to handle the high output from the S63M 4.4L V8 engine (up to 617 horsepower and 553 lb-ft of torque), the differential uses hardened steel gears and high-strength internal components.
  • Bearings and gears are designed for durability under the extreme conditions of high-performance driving.

Cooling and Lubrication:

• The rear differential has an integrated cooling system to manage heat generated under high loads, such as during aggressive driving or extended track use. Proper cooling ensures longevity and consistent performance.

Performance Benefits:

1. Improved Traction and Stability:
   • The electronically controlled M Differential and rear-biased xDrive system offer superior traction, helping prevent wheel spin during acceleration and providing better control during cornering.
2. Enhanced Handling:
   • The variable torque distribution improves turn-in response and allows for better handling by reducing understeer, especially when cornering aggressively at higher speeds.
3. Optimized Acceleration:
   • The 3.15 final drive ratio is ideal for fast acceleration, particularly when combined with BMW’s Launch Control system, which optimizes power delivery during take-off.

Compatibility:

• BMW M5 (F90): 2018-2022
• BMW M8 Convertible (F91): 2019-2022
• BMW M8 Coupe (F92): 2019-2022
• BMW M8 Gran Coupe (F93): 2020-2022