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Differential

Differential Layout

The Differential component models torque distribution between driven wheels, affecting traction, stability, and handling. It is an optional component — enable it via the toggle in the Powertrain page.

When disabled, an open differential is assumed.

The Differential is an independent library component — it can be saved, loaded, duplicated, and shared separately from the parent Powertrain.

Differential Types

Type Description
Open Allows wheels to rotate at different speeds with no torque transfer between them
Locked Forces both wheels to rotate at the same speed (50/50 torque split)
LSD Limited-slip differential with configurable locking behaviour based on torque and/or speed sensing

Differential Selection

  • Open: Smooth handling, no binding in corners, but poor traction when one wheel has low grip
  • Locked: Maximum traction to both wheels, but causes binding on high-traction surfaces
  • LSD: Adaptive — behaves like an open diff at low slip, progressively locks under higher slip

LSD Configuration

Differential Dialog

When LSD is selected, two independent sensing modes can be enabled via toggles. You can enable one or both simultaneously — their locking contributions are additive.

Torque Sensing

Responds to torque differences between output shafts. When enabled, a torque map editor opens with three input methods:

User-Defined Formula (FACES)

Uses geometric parameters to calculate a torque map:

Parameter Description Unit
Power Ramp Angle Ramp angle controlling progressive locking during acceleration degrees
Brake Ramp Angle Ramp angle controlling locking during deceleration degrees
Max Faces Maximum number of contact faces in differential mechanism count
Actual Faces Current number of active contact faces count

Simplified Ramp Settings

Direct locking control:

Parameter Description Unit
Drive Locking Locking ratio during acceleration decimal (0–1)
Coast Locking Locking ratio during deceleration decimal (0–1)
Preload Constant torque always applied to differential N·m

Table Input

Custom torque map for advanced modelling — define the relationship between input torque difference and delta torque transferred.

All three methods generate a 1D torque map (input torque vs. delta torque) that the simulation uses at runtime.

Speed Sensing

Responds to speed differences between wheels (viscous LSD behaviour). When enabled, a 1D map editor appears:

  • X-Axis: Speed difference between wheels (RPM)
  • Y-Axis: Locking torque (N·m)

See Data Types for details on map editors.

Validation Warnings

Condition Warning
LSD selected with no speed or torque map provided LSD differential is selected, but no speed or torque map is provided

Tips

  • Match to application: Open for street, LSD for performance, Locked for off-road or drag racing
  • Use FACES for clutch-type LSDs: The formula models mechanical clutch-pack behaviour with power and coast ramp angles
  • Use speed sensing for viscous LSDs: Viscous and helical designs respond to speed differences rather than torque differences
  • Combine both modes: Enable torque and speed sensing together for more complex differential behaviour

Next Steps