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Sim Racing Setup Tips and Tricks


There is a good line taken from the movie Days of Thunder, "loose is fast, but on the edge of control" This is perfectly true both in real life racing and in sim racing.

I like a loose racecar, but not an out of control one. So let's see if we can build a setup to do just that.

Disclaimer:
This document is not going to make you the next Greger Huttu or Greg Stewart. Hopefully what it will do is lower your lap times and more importantly improve your consistency. The text within these pages are based on knowledge I have picked up from racing my own cars and asking people in the know a lot of questions. Everything in here should not be taken as gospel, there are a lot of different ideas on how to make a car fast. What I want to do is to be able to drive quickly (relatively speaking) and do it with the least amount of drama possible.

No responsibility will be taken for bent rollover hoops, broken wishbones or square tyres.

Setups are all about compromise, every action has a reaction. Its how to get a nice balance that is the hard bit.

For starters, let's talk about the chassis and its reactions to setup changes.

The car will behave differently under different conditions and loads placed on it. For setup building, a fairly good understanding of how a car behaves is needed, this can be broken down quite easily. We really only need to concentrate on grip levels, the level of grip is entirely dependant on the ability of the tyre to adhere to the road surface.

There is two types of grip in a racecar, the first is aero-grip. This has no relevance to GPL at all, as the cars dont have wings. The second type of grip is mechanical grip. This is the grip generated by the suspension, allowing the tyres to create maximum friction with the road. This grip is both created and lost by the cars suspension and the loads placed upon it.

The more rubber in contact with the road, the more grip is generated. The weight of the car determines to a large extent the tyre contact, too little weight and the tyre will spin as the friction (in relation to the road surface) is not as great. If the weight placed on any one tyre is excessive, then the tyre will slide. The hard tyre, plus the suspension being loaded from the extra weight will lose all forgiveness in the chassis, so grip will be lost.

How the weight of the car reacts is the number one thing in setting up a car. The cars centre of gravity and roll-centres determine how much, and in what direction weight transfer is applied during the three phases of a racecar movement, acceleration, cornering and braking. We can't really delve into roll-centres because we do not know much about the cars suspension. We really have to look at it to work out roll-centres, so we will have to leave that.

Under hard acceleration the car will want to lean backward, that is the nose will move upwards and the rear of the car will be pushed downwards. Under heavy braking the car will do the opposite and under cornering the car will place more weight onto the outside of the chassis.

If the car is too soft the car will compress the tyres and suspension to an extent that grip will be lost because there is no give in it any more. If you overload a ute or similar type of vehicle, nearly every bump is felt because the suspension is transferring the road surface to the body of the car. The suspension has lost its ability to take the bumps out of the road. If the car is too hard there will be no "give in the suspension and the car will behave in a similar way to the above example.

Our aim then is to control this weight transfer, and use it to our advantage.

Anti-roll Bars:
A soft racecar will put the power down better to an extent, although the car will lose responsiveness, and will feel like a tug. That is the car "leans" its way around the track.

A stiffer car will be more direct in its feel, but overall grip is compromised.

It is my opinion (at the moment) to use less roll resistance at the front of the car. The front end has less weight, so should roll less under load. The engine/gearbox ass contributes to the overall weight of the car a lot, so my theory is to keep stiffer bars in the rear of the car, to counter the weight transfer effect.

If the bars are set too soft, especially the rear bar, the car will tend to spin the inside rear wheel more under hard acceleration. This can give an even bigger sense of either understeer, if mild wheel spin in maintained. Or snap oversteer if the spinning wheel grabs, the diff locking effect will oversteer the car.

More bar at the front/ less at the rear, makes the car stable by adding understeer. Less bar at front / more at rear, makes the car oversteer and will be less stable.

Most of the setups available use the bars set the first way, this will of cause add stability, these setups need all they can get because of the shock/spring/diff settings they have.

Wheel rates:
Wheel rate should be set to approximately equal weight distribution of the chassis, again soft equals more grip, but the car will wallow about a bit. Too soft will allow the car to bottom out, so the trade off is to raise the ride height. This adds to the body roll and causes further problems by creating more roll in the corners. The anti roll bars can then be used to help hold the unweighted side of the car to the road. This isn't a bad way to have a car behave, but a fair bit of tweaking is needed to tune everything correctly. The other end of the scale is to stiffen the car too much. This will cause the car to be very slidey and will feel skittish. There is really nothing you can do with a stiff car, except drive it very directly with the inputs given to it. The car has to be driven with precision or the tyres will overheat.

Bump/ rebound:
Shock absorbers are arguably what make a good racecar, it is a black art to a certain extent. The money spent in this area in the Australian V8Supercar series by the TWR operation for example is why they win so many races. Thank god we don't deal with four-way adjustable shocks in GPL. Two-way is hard enough.

Soft bump is good for braking, a lot of weight is transferred to the front wheels under heavy braking. The nose of the car tries to bury itself into the track surface. The down side is a car which will bottom out under braking, this isn't good as the car will tend to pivot off the front end, thus losing the rear. Although, the more we resist this weight transfer by making the front bump stronger, the more load the tyres have to cope with, and will lock easily.

Soft bump at the rear is good for power down at low speeds, the weight transfer will help get the torque to the road, it will also make the car feel unresponsive in the steering because the car is light at the front.

Stiff rebound will make the car more stable on corner exit at high speeds.

This is seriously hard to explain, so I think I will leave this section till some open testing is done. It will make much more sense to actually do it rather that read the same words over and over again. Results will be added here.

Tyre pressures:
Tyre pressures need to be set low enough so that they will not build up excessive pressure/temperature. The hotter a tyre gets, the less grip it will have. Setting pressures too low will result in excessive temperatures at the edges of the tyre, and will make the car very unstable for the first few laps. A nicely balanced car will keep its temperatures fairly even, although it should not be a concern if they are quite different because all racetracks are different. Salzburgring for example consists mainly of hard right hand turns, so naturally the left side tyres are going to be working harder.

Camber:
Camber is the angle of the wheel in relation to the road. Looking north-south at a car, the angle of the wheel is what we are after. If the top of the wheel is leaning into the car, this is negative camber. Negative camber allows the wheel to stay flat on the road as the chassis rolls from cornering forces. Nearly always use some negative camber at the front at least, and a little at the rear. More at the front will improve cornering grip, especially at turn in. More at the rear will enhance this turn in ability but will give more rear grip, so the car understeers a bit.

The only exception to this is with a NASCAR or oval based car, with a NASCAR you place a fair bit if positive camber on the left side of the vehicle.

Internet setups:
This section will sound like I am disagreeing with every one else's theory on setups, I am not. I am just trying to make setups, which are nice, and easy to drive, put which can also be quick enough to get decent times out of. I suppose until people start posting times for the two tracks last attempted (Red Rock Speedway and Salzburgring) we will not know just how fast they really are. My opinion at the moment is that my times achieved are about what I would expect from myself. If this is correct, then these setups should be able to help individuals to lower their rank to at least negative, and hopefully have a bit more enjoyment out of it at the same time.

Loose setups:
In order to get into the corners quick, a radical diff is used to allow for maximum trail-braking effect, this compromises grip both in the centre of the corner and the exit, right when power down is crucial. The lack of stability = more speed, at the effective loss of drivability.

The setups available tend to "fight" each other, this is, the diff is normally so loose on the coast side that less sway bar at the rear will delete some of that looseness. This works of course, but the car normally ends up very twitchy and "on the edge". The power side angles are normally quite low, meaning more locking effect, the rear dampers are normally set with more rebound, this aids corner exit grip. This once again deletes some of the loosening effects of the diff.

So the car is made loose by the diff settings, and is then some of that looseness is pulled out of the car by the suspension adding more rear grip. The compromise here is a huge one.

The cars are obviously very fast setup this way, but my opinion is that the cars are even harder to drive with these types of settings. The aim is to complete as many laps as possible, the sooner a driver can be comfortable with the handling of his car, the sooner a good pace can be maintained.

Any new setup, at any track will make for spins and written off cars, but if the chassis is more manageable, then the car will be easier to catch from a slide, and will be a lot more fun to drive. I have just completed four laps at Mexico and four at Monaco, and set new Cooper pb's at each. I don�t think that I have ever set a pb within so few laps before. And I haven't been to either track for at least six weeks.

Differential settings:
The differential is the most powerful setup tool we have in GPL. How the car behaves is greatly affected by what settings we choose.

Power side:
Less Locking (85) = inside wheel spins, less power to the ground, more forgiving oversteer (will oversteer if too much inside spin is invoked) "Easy" driving, feels slow.

More locking (30) = inside wheel spins less, better acceleration, can understeer, will snap oversteer with too much throttle.

"Touchy" setup, very good throttle control needed.

Coast side:
Less locking (85) = oversteer, will pull car to either side under braking depending on track surface or steering angle. Less locking will mean one of the rear wheels can lock because the wheels are "free-wheeling" more.

More locking (30) = understeer, more stable under braking, will lock both rear wheels at the same time in theory, will understeer on turn in.

Just remember...
Lower number = more locking
More locking = more understeer under braking

Clutches:
Less clutches = less locking effect
More clutches = more locking effect

Lower number means the diff will act like an open diff (road car) this allows freewheeling both under braking and under power.

This has the effect of oversteer into the corners (because the inside wheel can lock) and understeer on the way out of the corner. The exception to this is when to much inside wheel slippage results in oversteer, but this is generally a very gradual thing with a low number of clutches.

Higher number lets you shorten braking distances and brake with more confidence, the rear wheels are "mechanically attached" thus the diff gives a sense of "ABS" on the rear. The brakes cannot be used as much after turn in (trailbraking), further to this, the extra clutches mean more of a locked diff feel on the exits of corners. This will give better acceleration, but the result is too often massive power oversteer. This is due to the fact that when the inside rear wheel does spin, the outside wheel spins as well.

Wheel Rate (springs):
Balance front and rear wheel rates to be about the same proportion as front and rear weight distribution. Make wheel rate stiff enough to keep suspension from bottoming on the bump stops (or the track surface). Stiffer makes the car more skittish and nervous over bump; too stiff reduces grip. Too soft allows the car to wallow and requires higher ride heights to keep the suspension from bottoming.

Use: Light cars; 70 to 80 lb/in on front, 105 to 120 on rear. Heavier cars; 10 to 20 lb/in higher, in proportion to weight distribution. Can (but should not) be edited asymmetrically.

Bump/Rebound (dampers):
In general, make the dampers at each end equal to or stiffer on rebound than on bump. Stiffer on the front than rear will tend to make the car oscillate. Softer increases compliance and adds grip over bumps and in transition. Too soft allows the car to wallow, gives vague responses to steering and throttle inputs. Stiffer decreases compliance, makes the car more responsive, but reduces grip over bump and in transition. Too stiff makes the car nervous.

Stiffer in bump at the front, softer in rebound at the rear makes the car more stable on corner entry. Softer in bump at the rear, stiffer in rebound at the front makes the car more stable on corner exit. Too stiff on the front in bump can make the front brakes lock too easily. Too stiff on the rear in rebound can make the rear brakes lock too easily. Too stiff on the rear in bump can make it difficult to control the power at low speeds.

Stiffer rear dampers may require softer rear anti-roll bar and stiffer front anti-roll bar to keep the car manageable in transitions (turn-in/turning/accelerating). Stiffer on bump at the front will help reduce snap oversteer when hitting bumps or dips on corner entry. Faster circuits may need softer damping because the bumps are encountered at a higher speed.

Use: Typical setting is 2 on bump, 3 on rebound at the front. At the rear, use 2 or 3 on bump at the rear. If you use 2 on bump, try 2 or 3 on rebound; if you use 3 on bump, try 3 or 4 on rebound. 1 on bump in the front, and 2 on the rest on high speed circuits will increase grip on bumps but makes the car's responses to steering and throttle less precise. Can (but must not) be edited asymmetrically.

Camber (wheel inclination top-to-bottom):
Use tire temperatures as a guide. The goal is to make the inside temperature equal to or slightly higher than the outside temperature on each tire, but this is not a hard and fast rule. Often the more lightly used inside tires (typically the right side) will have higher temperatures on their inside edges and be fairly cool on their outside edges. Using asymmetrical camber to try to equalize these temperatures will tend to make the car unstable.

Increasing roll stiffness and/or lowering ride height will cause less camber change, and will tend to raise inside tire temperatures and lower outside tire temperatures. Too much camber at the front will make the car unstable under braking. Too much camber at the rear will reduce traction when accelerating out of low speed corners and will also reduce absolute grip in cornering. Too little camber at the rear will tend to make the car unstable; if it slides a little, it will tend to diverge; that is, slide more. Too little camber at the front will tend to make the car understeer, as will too much camber.

Use: Generally 0.5 degrees negative at the front, 0.25 or 0.5 negative at the rear. Should (but must not) be edited asymmetrically.

Bump Rubber:
Use the shortest possible bump rubbers as long as the car can be set up with springs and ride height so that it will not bottom the suspension or bottom the chassis on the track. If bottoming is unavoidable, use a high ride height and make the bump rubbers long enough to prevent the chassis from bottoming on the track, but short enough so that the suspension bottoms only in the places where the car encounters the most violent vertical loads.

Use: 0.5 inches on all currently available courses except the Nürburgring and Bristol. Should not be edited asymmetrically.

Toe-In (wheel parallelity):
More front toe-in (positive value) will make the car more stable, less responsive to steering inputs. Front toe-out will make the car more responsive to steering input. Too much front toe-in or toe-out will make the steering numb. More rear toe-in will make the car more stable in slides; as the side loads go up, rear toe-in will promote understeer. Too much rear toe-in will tend to overheat the outside edges of the tires.

Use: 0.025 inches front. At the rear, use .075 inches on long, stable cars, and up to .125 inches on shorter, more nimble cars. Can't be edited asymmetrically.

Roll-Bar Stiffness:
Stiffer in front, softer at the rear promotes understeer and makes the car more stable. Softer in front and stiffer at the rear promotes oversteer and makes the car less stable. Stiffer all around makes the car more responsive and crisp. Higher overall roll stiffness also reduces the difference in tire temperatures between the inside edge and the outside edge of the tires, particularly the outside tires in any given corner. Softer all around make the car more compliant and will reduce nervousness but also makes the car less responsive. Lower overall roll stiffness also increases the difference in tire temperatures between the inside edge and the outside edge of the tires.

Use: Set the anti-roll bars so you have a comfortable amount of understeer so that the car is stable, particularly on corner entry. You will wind up with front and rear bars fairly equal, with sometimes slightly higher rear, sometimes slightly higher front. Total roll stiffness for the lighter cars seems to wind up at about 300 to 320 or so. The wider cars need slightly less total roll resistance. On the GP Lotus, because of its wider rear rims, have considerably softer front anti-roll bar and stiffer rear anti-roll bar. Can't be edited asymmetrically.

Static Ride Height:
The lower the better, as long as the suspension does not bottom. Lower reduces the car's tendency to roll and reduces forward weight transfer under braking, allowing softer anti-roll bars and more rearward brake bias. Higher increases the car's tendency to roll and increases forward weight transfer under braking, requiring stiffer anti-roll bars and more forward brake bias.

Use: Start with 3.75, and lower if the circuit is very low-G and not bumpy. If necessary, raise the ride height to prevent the rear suspension from bottoming. Can't be edited asymmetrically.

Front Brake Bias:
More forward brake bias will make the car more stable under braking. If the bias is too far forward, the front brakes will lock too easily. More rearward brake bias will make the car more unstable under braking. If the bias is too far to the rear, the rear brakes will lock too easily and the car will be prone to spin under braking. If the engine note drops sharply under braking and then comes up when you ease off the brake, the bias is probably too far to the rear. Ideally, the front brakes should lock slightly before the rears.

Use: Between 54 and 58, with most cars around 55 to 57 at most circuits. Long, narrow cars (Brabham, Murasama), cars with rearward weight bias (BRM) and cars with lots of rear grip (the Lotus) can use more rearward brake bias. Short, wide cars (Ferrari) need more forward brake bias. Can't be edited asymmetrically.

Steering Ratio:
The higher the number, the slower the steering ratio. Short, wide cars need slower steering. Long, narrow cars need faster steering. Fast, open circuits may benefit from slower steering.

Use: 15:1 on the longer cars (Coventry, Honda) and 17:1 on the shorter cars, (Ferrari, BRM). Can't be edited asymmetrically.

Differential Power and coast angles:
The ramp angles are the major adjustment; the clutches are fine tuning. Ramps provide locking effect only when torque is being applied to the differential by the engine (ie. when the car is accelerating or decelerating). More locking effect (lower ramp angles) increases the car's stability. Too much locking on the power side, however, will result in snap power oversteer. Less locking effect (higher ramp angles) frees up the car on deceleration. Less locking effect will also allow more inside wheelspin on acceleration in slow corners, and will produce a more gradual transition to power oversteer. Too little locking on the coast side will make the car unstable in braking. Too little locking on the power side will hamper the car's ability to get the power down exiting slow corners.

Use: 85/30

Differential locking clutches:
The ramp angles are the major adjustment; the clutches are fine tuning. Clutches provide locking effect at all times. Clutches affect power side and coast side locking equally. More locking effect (more clutches) increases the car's stability. Too much locking on the power side, however, will result in snap power oversteer. Less locking effect (fewer clutches) frees up the car on deceleration and in midcorner. Less locking effect will also allow more inside wheelspin on acceleration in slow corners, and will produce a more gradual transition to power oversteer. Too little locking will make the car unstable in braking and will hamper the car's ability to get the power down exiting slow corners.

Use: Usually 4 clutches

Alternative interesting theories - does not comply with this setup guide!

60/30/2 Harsh and oversteery both on and off power

70/45/3 Considerably nicer but still oversteer based depending on the rest of your setup

75/45/4 Not too 'tricky' but you can't 'steer with the pedals' as accurately

Gearing parameters:
Top gear should be set so the engine does not quite reach redline at the end of the longest straight, when running alone. Use the tallest low gear you can use without the engine bogging at the start or accelerating away from slow corners. Use GPL Race Engineer and make the red-line dots go in a nice parabolic curve. The more torque the engine has, the closer together the top gears should be. The higher the engine's redline, the shorter the gears will be. Engines with low redlines will need taller gears. Heavier and more draggy cars need shorter gears. Lighter, cleaner, and more powerful cars will need taller gears.

Use: Varies according to engine and circuit.

Differential Gearing:
Use the differential gear that will give you the most desirable choices in gear selections. In some situations, 10/31 will not permit optimum gear spacing or the optimum top gear, so 9/31 may be a better choice. Cars with high-revving engines have more options; with low-revving engine on longer circuits, 2nd gear won't be tall enough even with the 10/31 ratio.

Use: For most cars on most circuits, 10/31. High-revving engines on short circuits may use 8/31 or 9/31; low-revving engines may use 9/31 on very short circuits.

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