The purpose of a differential is to allow the wheels on the left and right of the car to spin at different speeds. This is necessary when turning the car because the outside wheel needs to rotate more than the inside wheel in order to avoid slipping and loss of traction.
The differential is often used to tune the turning ability of the car, particularly in 4WD cars.
Differential types
Ball
- Smoother power delivery, especially in tight turns
- Generally recommended for loose or wet conditions
- Easier to adjust than gear diffs
- Lighter than gear diffs
- Requires occasional maintenance
Gear diff - 2-gear
- More off-power steering than 4-gear
- Capable of handling more power than ball diffs
- Characteristics determined by fluid viscosity
- Very low maintenance
Gear diff - 4-gear
- Less off-power steering than 2-gear
- Capable of handling more power than ball diffs
- Characteristics determined by fluid viscosity
- Very low maintenance
Solid axle (aka spool) in front
- Lighter than a diff
- Less steering & cornering speed
- Not used for off-road
- Is not actually a differential : )
Limited-slip (LSD / TCD)
- Limits energy sent to tires that don’t have traction. Standard diffs usually accomplish this by using heavier oil/grease.
- Only available for a few cars