Mopower Garage

Published by Christopher J. Holley | Mopar History & Tech | December 2025

The following is a clear comparison of the overhung pinion and straddle-mounted pinion arrangements used in automotive differentials.

Similarities

Both overhung and straddle pinions:

• Transmit torque from the driveshaft (via the pinion gear) to the ring gear in the differential.
• Maintain gear mesh with the ring gear and must be set with proper pinion depth and backlash.
• Use bearings to support the pinion shaft and handle axial (thrust) and radial loads.
• Are found in hypoid and spiral-bevel differential designs.

Differences

1. Bearing Support

Overhung Pinion

• Supported by bearings on one side only (toward the driveshaft).
• The pinion gear sits past the last bearing—like a weight hanging off the end of a shaft.
• Simpler layout but weaker support.

Straddle-Mounted Pinion

• Supported by bearings on both sides of the pinion gear.
• Typically uses three bearings: two tapered bearings around the shaft and one supporting the nose of the pinion.
• Gear is “straddled” between bearings for much stronger support.

2. Load Capacity

Overhung

• Lower load capacity.
• More shaft deflection under heavy torque.
• Suitable for light-duty applications.

Straddle

• High load capacity.
• Minimizes deflection and keeps gear mesh stable under extreme torque.
• Preferred for trucks, performance cars, towing, heavy-duty axles.

3. Gear Mesh Stability

Overhung

• Mesh can shift slightly under load due to bending, leading to:
  • More noise
  • Less durability
  • Potential for faster wear

Straddle

• Very stable mesh because the pinion is rigidly supported.
• Better noise characteristics and longer service life.

4. Manufacturing & Cost

Overhung

• Easier and cheaper to manufacture.
• Fewer bearings, simpler housing.

Straddle

• More complex differential housing required.
• Higher cost due to extra bearings and machining.

5. Common Usage

Type	Typical Use Cases
Overhung pinion	Small/light-duty cars, economy vehicles, some IRS diffs
Straddle-mounted pinion	Trucks, SUVs, performance cars, off-road, towing

Summary Table

Feature	Overhung Pinion	Straddle Pinion
Bearing support	One side only	Both sides of pinion gear
Strength	Lower	Higher
Deflection under load	More	Minimal
Gear mesh stability	Moderate	Excellent
Cost	Lower	Higher
Typical applications	Light-duty	Heavy-duty / high-performance