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Tuning reference /Diagnose

Diagnose by symptom

Pick the thing the car is doing wrong. Each entry lists the telemetry signal to confirm the diagnosis and the tuning levers to try, in order of how often they fix the problem.

  • Understeer on corner entry

    Entry
    Confirm in telemetry
    • Tire slip angle (lateral)
      Corner panels, "slip A" — compare front vs rear
      Front >> rear at the moment of turn-in
    • Brake input
      Trace strip, red line
      Are you still braking when steering? Trail-brake may be the cause
    Then try, in order
    1. 1.Brakes (Bias & Pressure)
      If trail-braking — shift bias 1–2% rear
    2. 2.Alignment (Camber, Caster, Toe)
      Front toe-out or higher caster helps turn-in
    3. 3.Anti-Roll Bars (ARBs)
      Soften front ARB if mid-entry still pushes

  • Understeer mid-corner (steady)

    Mid-corner
    Confirm in telemetry
    • Tire slip angle (lateral)
      Corner panels, "slip A" — compare front vs rear
      Sustained front-axle slip while throttle and brake are near zero
    • Tire temperature
      Corner panels, tire temp heatmap (cold blue → optimal green → hot red)
      Fronts hot, rears cold = chassis balance is front-limited
    Then try, in order
    1. 1.Anti-Roll Bars (ARBs)
      Soften front ARB first — cheapest, most targeted
    2. 2.Springs (Rate)
      If ARB alone doesn't fix it, soften fronts a touch
    3. 3.Aero (Downforce)
      In fast corners only: raise front aero

  • Understeer on power (exit)

    Exit
    Confirm in telemetry
    • Throttle input
      Trace strip, green line
      Symptom appears as throttle ramps in
    • Tire slip angle (lateral)
      Corner panels, "slip A" — compare front vs rear
      Front slip spikes after throttle application
    • Tire slip ratio (longitudinal)
      Corner panels, "slip R" — front/rear and L/R
      Driven-wheel L/R asymmetry shows open-diff slip
    Then try, in order
    1. 1.Differential (Accel & Decel)
      Lower accel % a step to let car rotate; or close the diff if open-wheel spin
    2. 2.Center Differential (AWD)
      AWD: shift center diff 5–10% forward
    3. 3.Anti-Roll Bars (ARBs)
      Soften front ARB if combined with mid-corner push

  • Oversteer on entry (lift-off)

    Entry
    Confirm in telemetry
    • Tire slip angle (lateral)
      Corner panels, "slip A" — compare front vs rear
      Rear-axle slip spikes when throttle goes to 0
    • Throttle input
      Trace strip, green line
      Are you fully off the gas before turn-in? Lift-oversteer arrives a beat after lift
    Then try, in order
    1. 1.Differential (Accel & Decel)
      Raise decel % — locks rear wheels together, more stable on engine braking
    2. 2.Alignment (Camber, Caster, Toe)
      Add 0.1–0.2° rear toe-in for stability
    3. 3.Dampers (Bump & Rebound)
      Soften front rebound to slow the front unloading on lift

  • Oversteer mid-corner (steady)

    Mid-corner
    Confirm in telemetry
    • Tire slip angle (lateral)
      Corner panels, "slip A" — compare front vs rear
      Rear >> front in steady cornering
    • Tire temperature
      Corner panels, tire temp heatmap (cold blue → optimal green → hot red)
      Rears hot, fronts cold = rear-limited chassis
    Then try, in order
    1. 1.Anti-Roll Bars (ARBs)
      Soften rear ARB first
    2. 2.Springs (Rate)
      If still loose, soften rear springs
    3. 3.Aero (Downforce)
      In fast corners: raise rear downforce

  • Oversteer on power (exit)

    Exit
    Confirm in telemetry
    • Throttle input
      Trace strip, green line
      Symptom appears as throttle goes in
    • Tire slip ratio (longitudinal)
      Corner panels, "slip R" — front/rear and L/R
      Rear-axle slip ratio > 0.1 = wheelspin
    Then try, in order
    1. 1.Differential (Accel & Decel)
      Lower accel % (less rear lock); for RWD also try lower decel if you can't commit early
    2. 2.Tire Pressure
      Drop rear 1–2 psi to widen contact patch
    3. 3.Center Differential (AWD)
      AWD: shift center diff 5% forward to bleed off rear torque

  • Front brake lockup

    Braking
    Confirm in telemetry
    • Tire slip ratio (longitudinal)
      Corner panels, "slip R" — front/rear and L/R
      Front slip negative under brakes; rear at ~0
    • Brake input
      Trace strip, red line
      Find the brake-trace peaks where lockup happens
    Then try, in order
    1. 1.Brakes (Bias & Pressure)
      Bias 1–2% rear; if still locking, drop pressure to ~95%

  • Rear brake lockup / spin under brakes

    Braking
    Confirm in telemetry
    • Tire slip ratio (longitudinal)
      Corner panels, "slip R" — front/rear and L/R
      Rear slip negative under brakes
    • Tire slip angle (lateral)
      Corner panels, "slip A" — compare front vs rear
      Rear slip angle climbing while braking straight
    Then try, in order
    1. 1.Brakes (Bias & Pressure)
      Bias 1–2% forward immediately
    2. 2.Dampers (Bump & Rebound)
      Check rear bump — bumpy braking can unload the rear

  • Bottoming over kerbs and bumps

    Bumps
    Confirm in telemetry
    • Suspension travel
      Corner panels, suspension bar (0..1, flashes red at >0.95)
      Bar pegs >0.95 frequently; flashing red
    Then try, in order
    1. 1.Ride Height
      Raise ride height before stiffening springs
    2. 2.Springs (Rate)
      If height is already up, raise the offending axle's springs
    3. 3.Dampers (Bump & Rebound)
      Bump damping shapes how the hit is absorbed

  • Wheelspin on launch / slow corners

    Exit
    Confirm in telemetry
    • Tire slip ratio (longitudinal)
      Corner panels, "slip R" — front/rear and L/R
      Driven wheels >> 0.1 with steady throttle
    • Gear
      Center panel
      Spin only in 1st gear → gearing; in all = diff or aero
    Then try, in order
    1. 1.Differential (Accel & Decel)
      Raise accel % if one wheel is doing all the spinning
    2. 2.Tire Pressure
      Drop pressure 1–2 psi to grow contact patch
    3. 3.Gear Ratios & Final Drive
      Lengthen 1st gear if launch-only

  • Tires overheating

    Mid-corner
    Confirm in telemetry
    • Tire temperature
      Corner panels, tire temp heatmap (cold blue → optimal green → hot red)
      >100 °C sustained; which corner is the worst?
    Then try, in order
    1. 1.Tire Pressure
      Raise pressure on hot corner by 1–2 psi
    2. 2.Alignment (Camber, Caster, Toe)
      Excess negative camber overheats the inside edge
    3. 3.Differential (Accel & Decel)
      Slipping diff overheats one drive wheel; raise accel %

  • Car oscillates / unstable on straights

    Straight
    Confirm in telemetry
    • Steering input
      Trace strip, yellow line
      Trace dances around 0 — constant correction
    • Suspension travel
      Corner panels, suspension bar (0..1, flashes red at >0.95)
      Oscillating bar = damper rebound too soft
    Then try, in order
    1. 1.Alignment (Camber, Caster, Toe)
      Add caster; reduce front toe-out
    2. 2.Dampers (Bump & Rebound)
      Raise rebound — both ends, 1–2 clicks
    3. 3.Aero (Downforce)
      High-speed instability: too little rear downforce