Before changing the setup
Understeer means asking the car to turn and watching it run wider because the front axle limits its ability to corner. Oversteer means the rear slides and the car rotates more than you intend. You do not need to spin to have oversteer, or leave the track to have understeer.
Do not diagnose it from tyre noise or wheel weight alone. Watch the path of the car, your steering input and whether you need opposite lock. Clipping force feedback or an incorrectly configured steering input can hide what the car is doing.
Start with a known setup, no damage and settled tyres. Check compound, wear, hot pressures, fuel and track conditions. The tyre pressure guide provides background; do not copy a target from a different car or from ACC into the original AC.
If the problem only happens over a kerb, try a line that avoids it first. If it began after a setup change, restore the previous setting. That tells you more than adding another adjustment. The tests below depend on the symptom; they are not a checklist of changes to apply together.
The same car can understeer at turn-in and oversteer on exit. Describe each phase separately rather than trying to fix both with an adjustment chosen from a general label.
Quick summary
| When | What you feel | Try first at the wheel | First setup test |
|---|---|---|---|
| Braking | Front runs straight as you turn on the brakes | Brake earlier and release progressively | Brake bias slightly rearwards, only if the fronts lock |
| Braking | The rear moves | Avoid over-revving downshifts | Brake bias slightly forwards |
| Turn-in | Won't reach the apex | Slower entry, smoother brake release | Slightly softer front anti-roll bar |
| Turn-in | Tail rotates too much as you steer | Gentler hands, finish downshifts earlier | A little more rear toe-in |
| Mid-corner | Runs wide with steady inputs | Lower entry speed, delay the throttle | Softer front bar (slow) or more front wing (fast) |
| Mid-corner | Rear drifts with steady inputs | Steady pedal, simple line | Softer rear bar (slow) or more rear wing (fast) |
| Exit | Runs wide on throttle | Point the car before accelerating | Fix mid-corner first; differential later |
| Exit | Rear steps out on power | Progressive throttle, avoid kerbs | Softer rear bar if loaded; otherwise power delivery |
One change at a time. If it does not improve repeatably, go back to the previous setup.
Under braking: separate locking from poor rotation
During completely straight braking you are not asking the car to turn: a front lock-up alone does not prove understeer. Balance becomes the issue when you start steering, or when the rear moves during deceleration.
The front runs straight while you brake
How to recognise it. You turn with the brake still applied, but the car will not tighten its line. If wheel motion or wheel speeds are available, check for front locking. With ABS, look at its intervention and the actual path of the car. No lock-up does not automatically mean spare grip for turning.
Could it be driving?. You are combining too much brake with too much steering, or carrying too much speed. Try starting your braking earlier and releasing pressure progressively as you turn. Test that entry first without changing the setup.
What to check. Pedal calibration, ABS where fitted, and front tyre pressures and condition. Compare with a slower entry to see whether the problem remains. A dark mark on the track is not enough to identify a lock-up.
First setup test. If front locking is confirmed and repeatable while the rear remains stable, try a small shift of brake bias rearwards within the car’s adjustment range. Check what the menu value represents: it commonly shows the front percentage. Revert if the rear becomes unstable. Without evidence of locking, do not move the bias on a guess.
The rear moves under braking
How to recognise it. The tail moves before you apply power, and you correct it while slowing down. Check whether it coincides with a downshift, a bump or the beginning of steering input.
Could it be driving?. A downshift that sends the revs too high, an abrupt clutch release or a sudden turn with heavy braking can unsettle the car. Separate those actions and repeat the same corner.
What to check. Rear wheel locking, brake bias and your gear change. Even with ABS, do not rule out a loss of support or a poorly matched downshift. If it happens only over a bump, brake bias may not be the cause.
First setup test. If the movement follows braking and there is evidence of excessive braking at the rear, move the bias slightly forwards. Repeat without another adjustment. If the front now locks or refuses to turn, you have gone too far. Do not use this change to cover up a bad downshift.
At turn-in: what happens as you release the brake
This phase runs from your first steering input until the car settles into the corner. It can overlap with braking. Identify the action that triggers the problem: adding steering, releasing the brake or lifting off the throttle.
The front will not reach the apex
How to recognise it. The car opens its line as you first turn, even if it settles afterwards. Extra steering barely changes the path. If you are still braking heavily, return to the braking checks.
Could it be driving?. Too much entry speed, a sharp steering input or a sudden brake release can cause it. Try a calmer entry and a continuous release of pressure. Holding some brake is not compulsory for every car or corner.
What to check. Steering configuration for your wheel or controller, front tyre condition and whether you are comparing a cold-tyre entry with a warm one. Separate a weak initial response from understeer that lasts through the entire corner.
First setup test. If it persists in slow corners on smooth tarmac, with no locking and a repeatable entry, try softening the front anti-roll bar slightly where adjustable. This tests mechanical balance; it does not guarantee a sharper initial response. Revert if extra roll makes turn-in or fast corners worse. Leave the springs alone during this test.
The rear rotates too far at turn-in
How to recognise it. The tail moves as you steer or lift, before you accelerate. If it starts with brake pressure, deal with braking first.
Could it be driving?. An abrupt turn, a sudden lift while cornering or a downshift during turn-in can trigger it. Repeat with gentler hands and finish the gear change before turning.
What to check. Rear tyres, damage, kerbs and any alignment change from your reference. A symptom during a brief transition does not prove that the dampers are wrong.
First setup test. If the rear stays nervous with clean inputs, try a small increase in rear toe-in, only where adjustable. Confirm the direction of the setting: a positive sign does not mean the same thing in every mod. Look for stability without making the car reluctant to turn. If the menu convention is unclear, leave alignment alone and return to a known reference.
Mid-corner: balance with the car settled
Choose a corner where you can hold a line with relatively steady inputs. If you are still releasing the brake or already asking for strong acceleration, you are mixing phases.
Mid-corner understeer
How to recognise it. With steady speed and inputs, the car opens its line and needs more steering without tightening the path enough. Check whether it also happens with a slightly slower entry.
Could it be driving?. You carried too much speed in, or started accelerating before completing the turn. Stop adding more steering. On the next pass, lower entry speed and delay the throttle to compare.
What to check. Pressures, front wear and whether it happens in slow corners, fast ones or both. A single temperature reading is not enough to prescribe a camber change. On aero cars, also check for bottoming out.
First setup test. In slow corners, with healthy tyres and no bottoming, try a slightly softer front anti-roll bar. Keep the rear bar unchanged. If the problem exists only at high speed and front downforce is adjustable, a small increase in front downforce may be a more relevant test; choose that instead of the bar. Do not lower ride height blindly.
Mid-corner oversteer
How to recognise it. The rear drifts with steady inputs and you need a correction to hold the arc. If it coincides with a throttle jab or lift, record it as a transition rather than steady balance.
Could it be driving?. Excess entry speed, abrupt corrections or small throttle changes can be hard to notice until you watch the replay. Try a pass with a simple line and steady pedal input.
What to check. Rear tyre condition, kerb contact and whether the problem grows only in fast corners. Check for bottoming or a loss of support caused by damage.
First setup test. In clean, slow cornering, try softening the rear anti-roll bar slightly where adjustable. This is a common balance tendency, which still needs checking on your car. For a problem confined to high speed, without ground contact, test more rear downforce where available. Choose according to the symptom; do not make both changes in the same run.
On exit: match the throttle to the steering that remains
Watch when the line starts opening or the rear begins sliding relative to throttle input. An apparent exit problem can start with reaching the apex before the car is pointed where it needs to go.
The car runs wide when you accelerate
How to recognise it. As you add power, the front stops tightening the line and you have to lift to stay on track. If the rear tyres slide and you also need opposite lock, there is oversteer as well as a poor line.
Could it be driving?. You ask for acceleration with too much steering remaining. Try finishing the rotation and add throttle as you unwind the wheel. An exit that forces you to lift later is often worse than waiting a little before accelerating.
What to check. Drivetrain layout, which wheels spin and whether understeer was already present mid-corner. In front-wheel drive, the front tyres must steer and transmit power. Do not diagnose every car as though it were rear-wheel drive.
First setup test. If it also understeers in slow, steady cornering, start with a softer front anti-roll bar and check the exit afterwards. If it happens exclusively under power, there is no universal setting: an adjustable differential deserves inspection, but its effect depends on drivetrain layout and which tyre loses grip. Without that evidence, leave the differential alone and test throttle application first.
The rear steps out under power
How to recognise it. The tail starts moving as throttle increases and you need opposite lock. Separate an inside wheel spinning from the whole rear axle sliding: they do not necessarily need the same solution.
Could it be driving?. Opening the throttle too quickly, using too low a gear or crossing a kerb under power can cause it. Try progressive application and a clean line. If that helps, you do not need to solve everything through setup.
What to check. Rear tyres, active assists, gear, differential locking and which wheels spin. Also check whether the car was already sideways before you applied power.
First setup test. On a rear-wheel-drive car, if the rear loses grip while still heavily loaded in cornering and its anti-roll bar is adjustable, try softening that bar slightly. If wheelspin starts with the steering nearly straight, the bar may offer little help: review power delivery and traction first. Do not prescribe less differential locking without separating inside-wheel spin from both tyres sliding.
How to test a change without fooling yourself
Save the reference setup and write down the symptom with a corner and phase: “the rear moves as I release the brake at turn-in”. Choose a hypothesis and the smallest useful change the menu allows. Step size depends on the car; verify that the new value really softens, stiffens or shifts bias in the intended direction.
Repeat with the same compound, starting fuel, assists and track conditions. Wait for the tyres to settle rather than prescribing a warm-up lap count for every car. Compare several clean passes and examine the troublesome corner as well as the lap time.
If one phase improves but another becomes worse, record it. If a change brings no repeatable benefit, restore the reference before testing another setting. The Assetto Corsa setup guide explains the parameters. Here the aim is to choose a worthwhile test, not to change everything.
Frequently asked questions
Will more steering fix understeer?
If the front axle is already sliding, extra steering may increase scrub without tightening the line. Review speed and braking, and test an entry that leaves grip available for turning.
Do understeer and oversteer always come from setup?
No. Driving inputs, tyres, damage and track conditions can all cause them. A setup test is useful when the symptom repeats in comparable conditions with controlled inputs.
How far should I change brake bias or anti-roll bars?
There is no setting that fits every car. Start with a small adjustment available on your car, confirm its direction and compare. Step sizes and scales can vary between cars and mods.
Should I change the differential first?
Only after identifying a problem related to power or overrun and checking the differential fitted to the car. Inside-wheel spin and loss of grip across the whole axle are different problems.
Can I use these settings in ACC and EVO?
This guide focuses on the original AC and does not provide universal settings. Diagnosis by phase is useful elsewhere, but tyres, assists, menus and specific adjustments need separate checks.
References for the principles
Driver61: Understeer · Driver61: Oversteer · Driver61: Trail braking
To support this process, Track Engineer uses stint analysis and setup information to propose changes and assess them against subsequent runs. The conclusion depends on the available data and on comparable tests; a proposal still needs checking on track.