Adjust
adjust car set-up to rectify handling problems
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Race cars are like prescription spectacles. Just as the spectacles have to be custom made for the wearer, a race car must be custom fitted to the driver and the track for the prevailing weather conditions. Before a car can be set up, the driver must test drive it in its factory set-up, and identify the handling problems, if any. This section describes how to identify handling problems during testing and how to rectify them upon returning to the pit. Drivers prefer a car that behaves predictably: follows the straights, feels stable during corner-entry braking, turns in crisply at corner entry, feels balanced mid corner, oversteers slightly at corner exit, and accelerates quickly along the subsequent straight.
The driving phases are defined as follows:
- Full throttle phase—travelling at full throttle along the straight
- Hard braking phase—braking hard before turning in for the corner
- Trail braking phase—continuing braking at turn-in
- Neutral throttle phase—remaining in neutral throttle at mid corner
- Initial acceleration phase—returning to throttle at corner exit
- Hard acceleration phase—resuming full throttle after having exited the corner
In each driving phase, specific issues may arise, either singly or multiply, under the following handling categories:
- Balance category—the car understeers or oversteers during cornering
- Compliance category—the tyres skip over bumps
- Manoeuvrability category—the car does not respond quickly to direction-change commands
- Responsiveness category—the car does not respond quickly to acceleration commands
- Stability category—the car does not track the straight line
In this section, I present ways to identify handling problems that may arise during each phase of driving, the symptom first, followed by a list of potential remedies. The remedies are listed in the order in which you should try. If the car you are driving does not have a particular set-up parameter, ignore it. When setting up an unfamiliar car, always establish the baseline lap time in the factory set-up. Never alter multiple parameters in one go; adjust only one set-up parameter by a small increment in only one direction, then test drive for a few laps. And note that many set-up parameters are intertwined, sometimes in unintended and unintuitive ways. Altering one parameter, for instance, may alleviate one kind of handling problem but simultaneously aggravate another kind of problem. And one parameter may affect multiple handling categories, or multiple parameters may affect one handling category. Careful analysis and disciplined approach are essential when setting up a car.
The goals of car set-up are as follows:
- Minimise the lap time—aim for the single best lap when setting up for qualifying, but when setting up for the race, aim for the lap times that are consistently good over many laps and are just slightly better than the competition
- Make the car handle well enough—it is impossible to make the car handle well in all phases of driving and in all corners on the track under all weather conditions, so just aim to minimise the car’s assorted misbehaviours, everywhere on the track, as much as possible
- Maintain tyre operating temperatures—all four tyres should operate within their optimal ranges through much of the race, and each tyre’s inner-middle-outer tread temperatures should be more or less equalised
- Minimise resource consumption—consumption rate of resources, like tyres, brakes, fuel, and driver stamina, should be reduced as much as possible, so that you can deploy the reserves at the end of the race when you pull ahead of the competition
FULL THROTTLE
compliance
- Tyres skip over bumps at high speed along the straight
- If the bumps are shallow and are closely spaced, just skip over them
- If the bumps are deep and are spaced far apart, ride them like a wave by modulating the throttle pedal
- Soften front and rear fast jounce and droop dampers
- Chassis scrapes the track at high speed along the straight
- Reduce fuel quantity if possible
- Reduce the front and rear wing angles
- Stiffen front and rear springs and dampers
- Stiffen front and rear heave springs and dampers
- Raise front and rear ride heights proportionately
manoeuvrability
- Steering feels vague while travelling at high speed along the straight
- Strengthen steering wheel controller force feedback
- Reduce fuel quantity if possible
- Stiffen front and rear anti-sway bars
- Stiffen front and rear slow jounce and droop dampers
- Lower front and rear ride heights proportionately
responsiveness
- Engine redlines before the car reaches the braking zone
- Lengthen top gear ratio and adjust gear spacings appropriately
- Lengthen final drive ratio
- Engine cannot reach rev limit when the car reaches the braking zone
- Shorten top gear ratio and adjust gear spacings appropriately
- Shorten final drive ratio
- Reduce wing angles
- Remove Gurney flap
stability
- Car does not follow straight line at high speed
- Increase front wheels toe in
- Increase steering castor angle positive value
- Car darts left or right over bumps at high speed along the straight
- Stiffen front and rear slow jounce and droop dampers
HARD BRAKING
balance
- Front wheels lock up before rear wheels under hard braking on level track surface
- Move brake bias rearward
- Increase MGU-K recovery rate
- Rear wheels lock up before front wheels under hard braking on level track surface
- Move brake bias forward
- Decrease MGU-K recovery rate
- Car spins off to the outside of corner under hard braking on a downslope
- Move brake bias forward
- Decrease MGU-K recovery rate
- Soften rear slow jounce and droop dampers
compliance
- Tyres skip over bumps under hard braking
- Soften front and rear fast jounce and droop dampers
- Front of chassis scrapes the track surface under hard braking
- Stiffen front springs and dampers and do the same to the rear to maintain balance
- Stiffen front heave springs and dampers and do the same to the rear to maintain balance
- Raise front ride height and do the same to the rear to maintain rake angle
stability
- Body dives hard onto front suspensions thereby deranging them
- Stiffen front heave springs and dampers
- Stiffen front slow jounce and droop dampers
- Stiffen front suspension springs
- Lower front and rear ride heights proportionately
- Car darts left or right over bumps under hard braking
- Stiffen front and rear slow jounce and droop dampers
TRAIL BRAKING
balance
- Car understeers at turn-in
- Reduce corner entry speed
- Move brake bias rearward
- Decrease corner entry differential lock
- Increase MGU-K recovery rate
- Lower front tyres pressures [OR] raise rear tyres pressures
- Soften front anti-sway bars [OR] stiffen rear anti-sway bars
- Decrease LSD coast side lock
- Decrease centre LSD preload
- Increase front wheels toe out
- Soften front springs [OR] stiffen rear springs
- Soften front slow jounce dampers [OR] stiffen rear slow droop dampers
- Increase front and rear wheels negative camber
- Car understeers at turn-in over bumps
- Soften front fast jounce and droop dampers [OR] stiffen rear fast jounce and droop dampers
- Car oversteers at turn-in
- Move brake bias forward
- Increase corner entry differential lock
- Decrease MGU-K recovery rate
- Raise front tyres pressures [OR] lower rear tyres pressures
- Stiffen front anti-sway bars [OR] soften rear anti-sway bars
- Increase LSD coast side lock
- Increase centre LSD preload
- Decrease front wheels toe out
- Stiffen front springs [OR] soften rear springs
- Stiffen front slow jounce dampers [OR] soften rear slow droop dampers
- Car oversteers at turn-in over bumps
- Stiffen front fast jounce and droop dampers [OR] soften rear fast jounce and droop dampers
compliance
- Tyres skip over bumps under trail braking
- Soften front and rear fast jounce and droop dampers
manoeuvrability
- Car feels floppy at turn-in
- Reduce fuel quantity if possible
- Stiffen front and rear slow jounce dampers
- Stiffen front and rear anti-sway bars
- Stiffen front and rear springs
- Lower front and rear ride heights proportionately
stability
- Car darts left or right over bumps under trail braking
- Stiffen front and rear slow jounce and droop dampers
NEUTRAL THROTTLE
balance
- Car understeers mid corner
- Decrease mid corner differential lock
- Increase MGU-K recovery rate
- Lower front tyres pressures [OR] raise rear tyres pressures
- Soften front anti-sway bars [OR] stiffen rear anti-sway bars
- Decrease LSD preload
- Decrease centre LSD preload
- Increase front wheels toe out
- Soften front springs [OR] stiffen rear springs
- Soften front slow droop dampers [OR] stiffen rear slow jounce dampers
- Increase front and rear wheels negative camber
- Car oversteers mid corner
- Increase mid corner differential lock
- Decrease MGU-K recovery rate
- Raise front tyres pressures [OR] lower rear tyres pressures
- Stiffen front anti-sway bars [OR] soften rear anti-sway bars
- Increase LSD preload
- Increase centre LSD preload
- Decrease front wheels toe out
- Stiffen front springs [OR] soften rear springs
- Stiffen front slow jounce dampers [OR] soften rear slow droop dampers
- Car skids away from the apex
- Soften front and rear anti-sway bars
compliance
- Tyres skip over bumps mid corner
- Soften front and rear fast jounce and droop dampers
manoeuvrability
- Car feels floppy mid corner
- Reduce fuel quantity if possible
- Stiffen front and rear slow jounce dampers
- Stiffen front and rear anti-sway bars
- Stiffen front and rear springs
- Lower front and rear ride heights proportionately
stability
- Car darts left or right over bumps mid corner
- Stiffen front and rear slow jounce and droop dampers
INITIAL ACCELERATION
balance
- Car understeers when accelerating out of corner
- Soften front slow droop dampers [OR] stiffen rear slow jounce dampers
- Decrease corner exit differential lock
- Decrease LSD power side lock
- Decrease centre LSD preload
- Car oversteers when accelerating out of corner
- Increase corner exit differential lock
- Increase LSD power side lock
- Increase centre LSD preload
responsiveness
- Engine redlines when accelerating out of corner
- Lengthen cornering gear and adjust gear spacings appropriately
- Lengthen final drive ratio
- Engine bogs when accelerating out of corner
- Maintain a higher speed through the apex
- Shorten cornering gear and adjust gear spacings appropriately
- Shorten final drive ratio
- Rear drive wheels spin at corner exit
- Reduce rear tyres pressures
- Increase rear wheels negative camber
- Increase LSD power side lock
stability
- Car fishtails when accelerating out of corner
- Return to throttle more gradually
- Set rear wheels toe angles closer to zero
HARD ACCELERATION
balance
- Car understeers under hard acceleration
- Soften front slow droop dampers [OR] stiffen rear slow jounce dampers
- Car oversteers under hard acceleration
- Stiffen front slow droop dampers [OR] soften rear slow jounce dampers
responsiveness
- Rear drive wheels spin under hard acceleration
- Reduce rear tyres pressures
- Increase rear wheels negative camber
stability
- Body squats hard onto rear suspensions thereby deranging them
- Stiffen rear springs and dampers
- Car fishtails when accelerating out of corner
- Return to throttle more gradually
- Set rear wheels toe angles closer to zero