Rules of Thumb
Use tire temperatures as a guide. On road courses and shallow ovals, make middle temperature approximately equal to average of inside and outside temperatures.
On steeply banked ovals, make middle temperature somewhat higher than average of inside and outside temperatures.
What I Use
20 psi all around on road courses; somewhat higher on steeply banked ovals. As high as 24 psi on left, 23 on right on steepest ovals.
See Also
Adapting Setups, Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Tire Pressures and Camber), Developing a Setup - Dialing it In (Balance and Fine Tuning), Introduction to Race Car Dynamics, The Tire
Rules of Thumb
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.
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.
What I Use
Light cars on road courses and shallow ovals: 70 to 80 lb./in. on front, 105 to 120 on rear. Heavier cars on road courses and shallow ovals, 10 to 20 lb./in. higher, in proportion to weight distribution.
On steep ovals, stiff enough to keep the suspension from bottoming with static ride height at about 4.5 inches.
See Also
Adapting Setups, Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Spring Rates and Ride Heights and Tire Pressures), Developing a Setup - Dialing it In (Balance and Fine Tuning), GRE Features, How Do I Know when It's Bottoming?, Introduction to Race Car Dynamics (Spring Rates and Ride Heights), Spring Rates and Ride Height, Chassis Weights and Dimensions, The Suspension, Troubleshooting
Rules of Thumb
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 droop 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.
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.
What I Use
On road courses and shallow ovals, typical setting is 2 on bump, 3 on rebound at the front.
At the rear, I use 2 or 3 on bump at the rear. If I use 2 on bump, I'll try 2 or 3 on rebound; if I use 3 on bump I'll use 3 or 4 on rebound.
I've been experimenting with 1 on bump in the front, and 2 on the rest on high speed circuits. This increases grip on bumps but makes the car's responses to steering and throttle less precise.
On steep ovals, I'll use very soft on the left front and stiffer on the others, going stiff enough at the rear to help the car turn.
See Also
Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Dampers), Developing a Setup - Dialing it In (Balance), How Do I Know when It's Bottoming?, Introduction to Race Car Dynamics (Transient States), Spring Rates and Ride Height, Damper Tables, The Suspension, Troubleshooting
Rules of Thumb
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 on road courses 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.
On ovals, I use positive camber on the left, negative on the right, setting them so that the inside and outside temps on each tire are roughly equal.
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.
What I Use
On road courses, generally I use .5 degrees negative at the front, .25 or .5 negative at the rear.
On ovals, I use positive camber on the left, negative on the right, setting them so that the inside and outside temps on each tire are roughly equal.
See Also
Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Camber), Developing a Setup - Dialing it In (Balance and Fine Tuning), GRE Features, Introduction to Race Car Dynamics (Tire Pressure and Camber and Balance), Spring Rates and Ride Height, The Suspension
Rules of Thumb
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.
What I Use
.5 inches on all currently available road courses and ovals except the Nurburgring and Bristol.
See Also
Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Spring Rates and Ride Heights), GRE Features, How Do I Know when It's Bottoming?, Spring Rates and Ride Height, Troubleshooting
Rules of Thumb
More front toe-in 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.
What I Use
.025 inches front. At the rear, I use .075 inches on long, stable cars, and up to .125 inches on shorter, more nimble cars.
See Also
Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Toe), Developing a Setup - Dialing it In (Balance), The Suspension
Rules of Thumb
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.
What I Use
I set the anti-roll bars so I have a comfortable amount of understeer so that the car is stable, particularly on corner entry.
On road and street courses, with most GP cars I 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, I'll have considerably softer front anti-roll bar and stiffer rear anti-roll bar.
With the Advanced Trainers, I may wind up with slightly softer overall roll resistance. Most of these seem to need somewhat stiffer front anti-roll bars compared to the rear. Basic Trainers tend to oversteer (due to skinny rear tires?) and therefore need even more stiffness at the front relative to the rear, and may use even less overall roll resistance.
On ovals, I tend to wind up with very stiff rear anti-roll bars, sometimes well over 200 lb./in., and fairly soft front anti-roll bars to help deal with understeer and the tendency to overheat the right front.
See Also
Adapting Setups, Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Camber), Developing a Setup - Dialing it In (Balance, Transients, and Fine Tuning), GRE Features, How Do I Know when It's Bottoming?, Introduction to Race Car Dynamics (Balance and Transient States), Chassis Weights and Dimensions, The Suspension, Troubleshooting
Rules of Thumb
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.
What I Use
I start with 3.75 on road courses and shallow ovals, and lower if the circuit is very low G and not bumpy. If necessary, I raise the ride height to prevent the rear suspension from bottoming.
On steep ovals, I use between 4.5 and 5 inches, stiffening the spring rates as necessary to prevent the rear suspension from bottoming.
See Also
Adapting Setups, Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Spring Rates and Ride Heights and Tire Pressures), Developing a Setup - Dialing it In (Balance and Fine Tuning), GRE Features, How Do I Know when It's Bottoming?, Introduction to Race Car Dynamics (Spring Rates and Ride Heights), Spring Rates and Ride Height, Chassis Weights and Dimensions, The Suspension, Troubleshooting
Rules of Thumb
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.
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.
The Trainers can use more rearward bias because they have less grip and therefore less weight transfer.
What I Use
Between 54 and 58, with most cars around 55 to 57 at most circuits.
See Also
Adapting Setups, Chassis Characteristics, Circuits, Developing a Setup - Basic Settings (Differential and Dampers), Developing a Setup - Dialing it In (Balance and Transients), How Do I Know when It's Bottoming?, Introduction to Race Car Dynamics (Differential, Balance, and Transient States), Damper Tables, The Differential, The Suspension, Troubleshooting
Rules of Thumb
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.
What I Use
15:1 on the longer cars (Coventry, Honda) and 17:1 on the shorter cars, (Ferrari, BRM). At the moment I don't change the ratio for fast or slow circuits, but this is an area for future experimentation.
See Also
Power/Coast Angles
Rules of Thumb
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 (i.e. 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.
What I Use
85/30 on all road courses. Note: as of late August 2000, I've begun to use 60/45 with one clutch on road courses. Click here to see why.
85/85 on fast ovals. On short ovals, something between these extremes as necessary to get good balance and not overheat the right front tire.
Clutches
Rules of Thumb
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.
What I Use
Usually 4 clutches on road courses. Note: as of late August 2000, I've begun to use one clutch with 60/45 ramp angles on road courses. Click here to see why.
On fast ovals, 1 clutch. On short ovals, I may use 2 or 3 depending on what's needed to balance the car, stabilize it on corner entry, and help get the power down on corner exit.
See Also
The Differential, Basic Settings, Introduction to Race Car Dynamics
Gear Sets
Rules of Thumb
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.
The redline dots in GRE's gear charts should 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.
What I Use
Varies according to engine and circuit.
Differential Gearing
Rules of Thumb
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.
What I 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.
See Also
Gearing Graph and Charts, Gear Ratios, Adapting Setups, Chassis Characteristics, Gearbox and Chassis Copy, Tables and Charts
Rules of Thumb
Each engine uses fuel roughly proportional to the power it creates. The more powerful the engine, the more power it uses.
[Note: GPL's setup menu shows fuel consumption estimates for the GP engines no matter what class of car you are driving.]
The higher you rev the engine, the more fuel it will use.
Internal engine friction may be a minor factor; engines with more friction will probably use a bit more fuel. Interenal friction is roughly proportional to the number of cylinders; the BRM seems to have a lot of friction, and I think the Ferrari has more than, say, the Cosworth or the Repco V-8's. The Weslake, howerver, seems to have relatively low internal friction considering it's a V-12.
What I Use
I use the estimates in GRE's fuel calculation feature.
See Also