Use tire temperatures as a guide. Make middle temperature approximately equal to average of inside and outside temperatures. Decrease pressure to lower the middle temperature and increase pressure to rise middle temperature. Tyres must be "hot".
Use: 20 psi all around. Can (but must not) be edited asymmetrically.
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.
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.
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.
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.
Limited slip differential parameters:
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.
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
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.
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.