Forza Motorsport: car bottoming out — what to change
What it feels like
Over fast sections or compressions the floor hits the track, the car bounces and you lose grip exactly there.
Why it happens and what we're after
The car bounces / bottoms out: raise ride height and soften springs a touch to give travel and stop the floor hitting the track.
What to change, exactly
Ranges, steps and defaults are the REAL ones for this sim. The amount is expressed in the game's own unit so you can apply it without converting anything.
Parameters flagged as “estimated range” do not come from a verified in-game capture: the direction of the change is right, the exact magnitude may differ on your car.
1.Front ride height
Raise ↑ by 0.4 in4 slider stepsestimated rangeRange: 2.0 – 8.0 in · Default: 3.2 in
Front floor-to-ground distance (unit inches, also selectable in mm). Lowering it drops the centre of gravity and can add aero load, risking grounding out. (generic class range, estimated)
What changes when you move it this way
Raising gives more travel and less bottoming risk, costing some aero load and raising the centre of gravity.
2.Rear ride height
Raise ↑ by 0.4 in4 slider stepsestimated rangeRange: 2.0 – 8.0 in · Default: 3.6 in
Rear ride height. Along with the front it sets the car's 'rake', relevant on cars with a real floor/diffuser. (generic class range, estimated)
What changes when you move it this way
Raising the rear can cut rear aero load if pushed past the optimal point.
3.Front spring rate
Lower ↓ by 30 lb/in3 slider stepsestimated rangeRange: 100 – 1500 lb/in · Default: 550 lb/in
Front spring stiffness (unit lb/in, also selectable in N/m or kgf/mm). A real GT3/GT4 runs very stiff springs compared to a road car. (generic class range, estimated)
What changes when you move it this way
Softer = more mechanical grip and better over bumps, with more roll and a slower response.
4.Rear spring rate
Lower ↓ by 30 lb/in3 slider stepsestimated rangeRange: 100 – 1500 lb/in · Default: 600 lb/in
Rear spring stiffness. Along with the front it sets the car's stiffness balance. (generic class range, estimated)
What changes when you move it this way
Softer rear = more mechanical rear grip, slower response.
How to apply it without losing your afternoon
- 01Change ONE thing at a time and run three clean laps before judging. Two changes at once and you no longer know which one worked.
- 02Start with the first parameter on the list: they are in the order the engine applies them, from the one with most authority to the fine tuning.
- 03If the change goes the right way but falls short, repeat the same step again before touching another parameter.
- 04If it gets worse, put it back. A setup you don't understand is slower than a baseline you do.
Where this sim stores its setups
Forza Motorsport (Xbox Series X|S and PC) saves setups inside the game itself with a custom name (car tuning screen), with no native export to an on-disk file (unlike iRacing/ACC/AC1/rFactor2 in this catalogue). To share a community setup, the verified way is to copy the values by hand into the in-game editor.
Want the exact values, not just the direction?
The generator takes your car, your track, the weather, grip and fuel, and returns the full setup with the reasoning behind every number. Free to start.
Car classes covered in this sim: GT3 · GT4 · GTE (etiqueta real de automovilismo — fuente del juego los agrupa junto a GT3, ver notas) · Prototipo LMDh/Hypercar (etiqueta real de automovilismo — fuente del juego lo agrupa junto a GT3, ver notas) · Turismo / GT de calle
Free to start: you only need an account, no card.
If that wasn't it
Symptoms get confused with each other: what feels like poor traction is very often oversteer on throttle. These are the other diagnoses for this sim.
- Understeer on corner entryYou turn in and the car keeps going straight: it washes wide before the apex.
- Mid-corner understeerMid-corner, at steady speed, the car refuses to hold the line and you have to unwind the wheel.
- Understeer on corner exitAs you get on the throttle the car pushes wide and runs out of road on exit.
- Oversteer on corner entryAs you release the brake and turn in, the rear steps out and the car rotates too much before the apex.
- Mid-corner oversteerMid-corner the rear keeps sliding on its own and you are correcting with the wheel the whole way through.
- Snap oversteer on throttleYou get on the power on exit and the rear snaps sideways: spin, or a big correction.
- Unstable under brakingBraking hard in a straight line the car moves around, the rear tries to come round or you lock up.
- No traction on corner exitOn exit the driven wheels spin and the car won't hook up: you lose time down the next straight.
- Tyres overheatingGrip falls off after two or three laps and temperature or pressure climbs past the window.
- Tyres not coming up to temperatureThe first laps the car slides everywhere and the tyres take forever to switch on.
- Unstable over kerbsTouch a kerb and the car jumps, gets unsettled, and you end up avoiding kerbs to keep it.
The same problem in other sims
Same symptom, different parameters: each game exposes different sliders, with other units and other ranges.