CAR SETUP

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image of setup adjustments for a race car
SETUP GUIDE

ANTI-ROLL/ SWAY BAR ADJUSTMENT EFFECTS ON HANDLING.

Lets have a look at the way we can adjust understeer and oversteer handling characteristics with the adjustment of anti-roll bars, also what effect the actual settings will have on the car if the stiffness is set too high.

Problem-

Solution-

Understeer.

  • Reduce front or increase rear anti-roll/sway bar settings.

Oversteer.

  • Increase front or reduce rear anti-roll/sway bar settings.

Anti-Roll/Sway Bar Setting-

Effect-

Too Much Anti-Roll/Sway 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/Sway Bar: Front.

  • Increased oversteer tendencies.

Too Much Anti-Roll Bar/Sway: Rear.

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

CAMBER OVERVIEW.

Lets have a look at the effect of different negative and positive camber settings on vehicle handling and tyre performance.

Problem:

Possible Causes:

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.

DAMPING EFFECT:

The overall damping effect has the following effects on the car handling behaviour:

Damping Setting.

Effect.

Stiffer front damping (bump and rebound):

  • Increases grip at the rear of the car, increasing understeer characteristics.

Stiffer rear damping (bump and rebound):

  • Increases grip at the front of the car, increasing oversteer characteristics.

BUMP:

During bump, the dampers and springs absorb the upward movement from cornering or road irregularities (the springs store some of the energy), the dampers then goes into rebound. If there isn’t enough damping then the cycle begins again until the car returns to the original ride height, with a bouncing motion to the car. Another trait of under damping is that loads go into tyre and suspension relatively slowly, this combined with the bouncing effect means a constant varying download force on tyres. Acceleration, braking or cornering in this state, will also vary due to the various download rates. It is important to have enough bump stiffness to be able to deal with uneven surfaces.

If there is too much damping, then it is effectively like running no suspension and any upward motion will be transmitted directly to the chassis. Over damping will result in a increase in the loads acting on the suspension and the tyres. The handling will feel very harsh and hard, this will effect street driving in terms of comfort levels, this might not be desired for a daily driver.

It is undesirable in both under and over damping settings, as it will reduce the handling of the car and will affect acceleration, braking and cornering loads.

Problem:

Possible Causes:

To Much Bump Setting

  • Initial bump reaction harsh.

  • Slow chassis roll.

  • Car may jack up in long corners (higher ride height).

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

REBOUND:

During rebound (following the bump compression phase) the dampers extend back to their original positions, using up the stored energy from the springs. The rebound stiffness needs to be set at a higher value then the bump setting as the stored energy is being released. If there is not effect damping on the rebound, the wheel will quickly return through the static level and start to bump again, with the bouncing effect unsettling the suspension with little control. Any racecar which intends to ride the kerbs on apexes, watch out- the compressed wheel could jump of the kerb in extreme instances of rebound setting being too low.

If there is too much rebound stiffness, then the wheel could hold longer in the wheel arch then needed, effectively losing contact with the road as the force to push the wheel back down is slower to respond to the changing surface levels. This state is again far from ideal and it is best to make sure a good level is set for optimal tyre contact with the road.

Problem:

Possible Causes:

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).

Too Little Rebound Setting.

  • Car will oscillate after bumps (bounce along the road).

  • Hard to put down power.

DAMPING EFFECT ON CORNERING CHARACTERISTICS.

Below we have an indication of how bump and rebound will affect handling characteristics, at the front and the rear of the vehicle:

Bump Setting:

Effect:

Front Bump Increase.

More Understeer.

Front Bump Decrease.

More Oversteer.

Rear Bump Increase.

More Oversteer.

Rear Bump Decrease.

More Understeer.

Rebound Setting:

Effect:

Front Rebound Increase.

More Understeer.

Front Rebound Decrease.

More Oversteer.

Rear Rebound Increase.

More Oversteer.

Rear Rebound Decrease.

More Understeer

RIDE HEIGHT

There are good reasons for reducing the ride height:

  • Lower centre of gravity-reducing weight transfer levels and aiding handling characteristics on the limit.

  • Lower suspension system roll centres- depending on the exact suspension configuration, roll centres which are too high cause too much lateral loads during cornering, overloading tyres.

  • Increased aerodynamic down force- the front ride height should always be slightly lower then the rear to gain a rake effect (reducing lift) to aid down force. This works especially well with flat under-bodies and diffuser combinations.

  • Reducing drag levels and increasing fuel economy, by restricting high pressure air from entering under the body. Especially effective with aerodynamic devices like front splitters and air dams for example.

    Ride Height Adjustment:

    Angle of Attack Effect:

    Lower Front Ride Height

    Increased angle of attack for both wings.

    Raising Front Ride height

    Decrease angle of attack for both wings.

    Another point to bear in mind, is that the pitch and softness of the front or rear suspension, will also have an effect on the aerodynamic package. Especially under acceleration and deceleration to a certain degree.

SPRING RATES OVERVIEW.

Problem:

Possible Causes:

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.

TOE-IN AND TOE-OUT AND TYRE WEAR.

Toe Setting:

Tyre Wear Effect:

Too much Toe-In.

  • This causes the outsides of the tyres to wear out more quickly.

Too much Toe-Out.

  • this causes the insides of the tyres to wear out more quickly.

As we can see the toe settings of the wheels has a big impact on the wear rates of the tyres. Uneven tyre wear is a good sign that the tyre´s contact patch is not fully working to its full capacity. This will reduce all lateral and longitudinal acceleration forces including acceleration, braking and cornering.

TOE-IN AND TOE-OUT AND STRAIGHT LINE STABILITY.

Problem:

Possible Causes:

General Straight Line Instability.

  • Too much toe-in or toe-out settings.

  • Rear toe-out static due to incorrect setting.

Straight Line Instability: Under Hard Acceleration

  • Too little rear toe-out setting.

Straight Line Instability: Car Darts over Bumps.

  • Too much toe-in or toe-out setting.

If straight line stability is affected by the toe-in and toe-out settings, we will see a reduction in overall acceleration and braking capacities. This will have a big impact on lap times and tyre wear rates, as previously highlighted.

TOE IN AND TOE OUT AND CORNERING.

Problem:

Possible Causes:

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

  • Too much front toe-in setting.

Corner Entry Oversteer.

  • Too much rear toe-in setting.

Corner Exit Oversteer: Progressively Increasing on Throttle Application.

  • Low rear toe-in setting.

Cornering capabilities are also affected but toe settings, this is also another indication that the tyres are not working at full potential. Inducing both oversteer and understeer handling characteristics.

TOE SETTING OVERVIEW.

Toe Setting:

Effect:

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 0ut: Rear.

  • Straight line instability.

  • Power oversteer on corner exit.

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.

BRAKE BIAS

Overview
-> More bias at the rear – increases oversteer
-> More bias at the front – increases understeer
-> Correct bias results in stability and predictability during braking and turn-in

Notes: The default values for the brake bias in Assetto Corsa follow the natural driving characteristics of a particular car. The Z4 GT3 for instance has great front brake bias, because of the long bonnet and heavy front structure. Don’t mess with the brake bias too much. You may shift the brake bias towards the rear in an attempt to decrease braking distance. Do so one point at a time, until you experience instability under braking. After, apply one point bias to the front for stability and reliability. You may apply more Toe-In (postive) in order to increase braking stability, albeit sacrificing performance during cornering.

DIFFERENTIAL (INCREASE = LESS LOCK)

Differential on acceleration (Diff: Power)
+/- Decreases understeer, especially out of tight corners
+/- Increases oversteer
+/- Decreases spin of the tyre without traction
+/- Lowers tyre temperatures slightly

Differential during braking and coasting (Diff: Coast)
+ Increases braking stability, effective
– Decreases willingness to turn
+/- Increases understeer

FRONT AND REAR WING VALUES

Generally, the rear wing should be as low as possible to gain higher top speed and yes, in contrast to some other games (Gran Turismo, F1 2012) this setting has a measurable effect in Assetto Corsa. However, you should start with a low value and increase it to gain stability through high speed corners and S-corners, if needed. For instance I found the rear wing to be much too high on the Z4 GT3 at default, which is surprising, because it’s prone to oversteer. A higher rear wing counters oversteer due to tyre degredation well.
If possible, the front splitter should always be on/engaged – more front end grip with no tangible detriments.

FUEL LOAD

This is straightforward: look how much fuel you as an individual driver use with a particular car & track combination, multiply by the amount of laps you want to go or have to race and there you go. Don’t cut it too close, all the setup work, preperation and your race performance is for not, if you run out of fuel just before the last couple of corners.

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