Handling Diagnostics

General Straight Line Instability.

Straight Line Instability: Under Hard Acceleration.

– Worn out or malfunctioning Limited Slip Differential.- Too little rear toe-out setting.

Straight Line Instability: Car Darts over Bumps.

– Too much toe-in or toe-out setting.- Uneven front castor setting.- Uneven front shock forces or bump rubbers.- Front anti-roll bar set too stiff.

Instability Under Braking: Front end Darts or Wanders.

– Too much front brake bias setting.

Instability Under Braking: Car feels like its going to spin.

– Too much rear positive camber settings and/ or too much rear brake bias setting.

Corner Entry Understeer: Car Struggles to Turn In and is Progressively Worse.

– Braking too hard and too late.- Insufficient front track width.- Too stiff front anti-roll bar setting.- Too soft front anti-roll bar setting.- Low front roll centre.- Too low front bump setting.- Low front down force.- Too much positive front camber on outside wheel.

Corner Entry Understeer: Car Turn In Good, then Progressively Washes Out.

– Too much front toe-in setting.- Low front down force.- Low front camber roll compensation.- Non linear load transfer, due to roll axis inclination.- Low front bump or rebound setting.

Corner Entry Understeer: CCar Turn In Good, then Darts.

– Low front bump or rebound setting.- Too high front down force levels

Corner Exit Understeer: Slow Corners.

– Excessive corner entry speeds.- Mid corner throttle application, with understeer present and steering lock applied.- Adjust driving style to improve throttle application and response.- Too hight front rebound setting.- Reduce rear anti-squat setting if present.

Corner Entry Oversteer.

– Broken or locked front anti-roll bar or rear outside shock.- Interference to rear suspension travel.- Too stiff rear anti-roll bar or spring rating.- Loss of rear down force.- Too much rear toe-in and/or rebound.- Carrying too much speed into the corner, or lift off oversteer.

Corner Exit Oversteer: Progressively Increasing on Throttle Application.

– Damaged limited slip differential.- Too soft rear anti-roll bar, spring or shock rating.- Low rear down force levels.- Low rear toe-in setting.- Too much rear camber setting.- Too stiff anti-roll bar.

Corner Exit Oversteer: Car takes its Set and suddenly breaks loose.

– Too much throttle application.- Sudden rear outside tyre camber change.- Lack of rear suspension travel.- Damaged rear shock.- Too much rear bump setting.

Too High Front Roll Centre and Too Low Rear Setting.

– Increased rear load transfer resulting in increased oversteer.- Non linear chassis roll and load transfer.- Roll axis out of parallel with mass centroid axis.

Too Low Front Roll Centre and Too High Rear Setting.

– Increased front load transfer resulting in increased understeer.- Non linear chassis roll and load transfer.- Roll axis out of parallel with mass centroid axis.- Possible three wheeled motoring on corner exit.

Too Narrow Front Track Width Compared to Rear Track Width.

– Increased understeer in slow and medium corner turn in.- Increased front track required.

Too Much Spring Rate: General.

– Harsh and choppy ride, hard to put power down on corner exit.- Sliding and excessive wheel spin on corner exits.

Too Much Spring Rate: Front.

– Turn in understeer, but car may point to apex well.- Front tyres locks on bumps and may break away.

Too Much Spring Rate: Rear.

– Excessive wheel spin.- Oversteer on corner exit.

Too Little Spring Rate: General.

– Car prone to bottom out on race track.- Excessive vertical chassis movement.- Floating ride feel.- Unresponsive feel.- Car may take multiple sets to settle.

Too Little Spring Rate: Front.

– Bottom out under braking loads.- Car rolls excessively during corners.- Understeer on turn in.

Too Little Spring Rate: Rear.

– Acceleration squat and increased negative camber.- Power oversteer tendencies on throttle application.

Too Much Anti-Roll Bar: General.

– Lack of feel with sudden response.- Prone to slide or skate rather then taking a set.- Darting over one wheel or diagonal bumps.

Too Much Anti-Roll Bar: Front.

– Increased oversteer tendencies.

Too Much Anti-Roll Bar: Rear.

– Increased corner exit oversteer, hard to put power down with excessive sliding.

To Much Shock: Overall.

– Car does not absorbed road irregularities, but crashes over them.- Harsh ride with a lots of sliding and sudden changes to ride.

To Much Rebound Setting.

– Wheel can not keep up with road surface changes.- Inside cornering wheel could be pulled of road by shock.- Car could become jacked down in long corners (lowered ride height)

To Much Bump Setting

– Initial bump reaction harsh.- Slow chassis roll.- Car may jack up in long corners (higher ride height).

Too Little Shock: Overall.

– Floating ride feel.- Car will oscillate after bumps (bounce along the road).- Slow and sloppy response.- Quickly develops chassis roll.

Too Little Rebound Setting.

– Car will oscillate after bumps (bounce along the road).- Hard to put down power.

Too Little Bump Setting

– Soft bump reaction.- Car prone to dive or squats, lots of longitudinal weight transfer.- Lots of car roll, inside front on turn in and outside rear on exit could fall over.

Damaged shock on one corner.

– Hard to identify and isolate.- If at rear, increased power oversteer and if at front increased understeer in one direction.

Car Feels Heavy and Unresponsive.

– Too much downforce.

Car feels soppy and rolls a lot and is slow to settle in corners.

– Too little damping settings on suspension.- Too soft anti-roll bar settings (roll resistance) or ride rate.

Car Feels on Edge, Responds too quickly to Inputs with Lack of Feel and wants to Slide all the time.

– Low down force settings.- Too stiff anti-roll bar settings (roll resistance) or ride rate.- High shock setting.- High tyre pressure.

Too Much Tyre Pressure.

– Harsher ride, especially over bumps.- High temperature in the centre of the tyre.- Increased tyre wear on centre of tyre.- Sliding and wheel spin.

Too Little Tyre Pressure.

– Soft ride.- Unresponsive steering.- Higher tyre temperature at inside and outside edges.- Increase wear rates at inside and outside of tyre.- Reduced overall traction, due to decrease in tyre foot print.

Front Tyres Losing traction.

– Increased understeer tendencies.- More oversteer needs to be dialled in to the handling balance.- Anti-roll bar or suspension adjustments needed.

Rear Tyres Losing traction.

– Increased oversteer tendencies.- More understeer needs to be dialled in to the handling balance.- Anti-roll bar or suspension adjustments needed.

Too Much Toe-In: Front.

– Car darts over bumps during braking loads and corner entry.- Hard to turn in on corner entry, if extreme will turn in then wash out.

Too Much Toe-Out: Front.

– Car wanders under braking.- Unstable in straight lines.- Reacts to wind gusts, one wheel or diagonal bumps.

Too Much Toe-In: Rear.

– Rear end unstable and light on corner entry.

Too Little Toe-In: Rear.

– Power oversteer on corner exit.

Toe Out: Rear.

– Straight line instability.- Power oversteer on corner exit.

Too Much Wheel Castor: Front.

– Excessive steering effort required.- Too much self return action.- Transmittal of road shocks to steering wheel.

Too Little Wheel Castor: Front.

– Car sensitive to steering effort.- Lack of steering feel.- Self return action and feedback reduced.

Uneven Wheel Castor: Front.

– Bias steering response on one side.- Car prone to swerve on higher castor setting side, on a straight line.

Too Much Negative Camber.

– Increased inside tyre wear.- Increased heat on inside of tyre.- Reduced front braking capacity.- Reduced rear acceleration capacity.

Too Much Positive Camber: Front.

– Increased understeer after turn in on cornering.

Too Much Positive Camber: Rear.

– Increased outside tyre wear.- Increased heat on outside of tyre.- If extreme could cause turn in response instability.- Increased corner exit oversteer.

Too Much toe-in in bump: Front.

– Increased understeer on corner turn in.- Car darts over bumps.

Too Much toe-out in bump: Front.

– Increase understeer after turn in on corner entry.- Car wanders under braking.- Car may dart over one wheel bumps or gusts of wind.

Too Much toe-in in bump: Rear.

– Darting on throttle application on corner exits.- Roll understeer on corner turn in.- Rear end instability on corner turn in.

Too Much toe-out in bump: Rear.

– Increased oversteer on power application.- Similar to static toe-out, to a lesser degree.