Differential preload
The baseline locking torque a limited-slip differential carries before ramps or clutches add more. Higher preload keeps the two driven wheels coupled earlier and more of the time: on-throttle it tends to add traction and stability, off-throttle it tends to stabilise the entry but resist rotation, feeling like entry understeer. Lower preload frees the car to rotate but can make the transition on and off throttle less predictable. It interacts with every phase of the corner, so evaluate a change across the whole corner, not just where it was aimed.
Effect by corner phase
Higher preload tends to hold the car straighter off-throttle, trading rotation for stability.
The locking state through the transition shapes how the car takes power without unsettling the balance.
Higher preload tends to help traction with both wheels driving, especially out of slow corners.
Symptom tendencies
These describe tendencies, not rules.
Entry understeer — the car resists rotation on corner entry when lifting off Entry
Less preload tends to free the entry; watch for a matching loss of stability in the same place.
Inside wheelspin out of slow corners Exit
More preload (or more on-throttle locking) tends to couple the wheels sooner and put power down cleaner.
Exit understeer — the car will not take the throttle without running wide Exit
Less on-throttle locking, or less preload, tends to let the driven wheels turn at different speeds and free the nose on exit — at some cost in traction stability. Re-check the same corner before stacking another change.
Verify on track before you commit to a change.