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โ–ผ Pit wall and graphs below

No lap loaded

Pick a session and a lap on the left, or switch to Live with Assetto Corsa running.

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Track map

Details
Camera
โ–ผbelow
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Repeat:
you / AC measured reference / model hardware Click a chart or the map to seek. Drag to scrub.
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Speed ยท tap to change channel

All data streams

channelvalueminmaxlast 30 s
Turn your phone sideways: the graphs and the 3โ€‘D view get a lot more room.

About

ACST: Assetto Corsa Suspension Telemetry

Every lap, taken apart

ACST is a telemetry bench for Assetto Corsa, built around one question: what was the car actually doing?

It records the parts of a lap you can't feel through the wheel: wheel loads, suspension travel and camber; roll, pitch, slip and tyre temperatures; and exactly where on the circuit each of them happened.

It then replays all of it beside a physical model of the same car. Where the model and the game agree, you learn how the car works. Where they disagree, you learn something more useful, because the disagreement is the interesting part.

Where the laps come from

Every lap here was driven on a Moza R5 wheel base in Assetto Corsa and recorded in one of two ways.

The leaderboards

Each circuit has its own board, drawn from the line actually driven.

Reading a lap

  1. Choose a lap. Open a time from a leaderboard, or pick a session and replay a lap from the start or jump straight to the best lap. The repeat control decides whether the session or the lap loops.
  2. Watch the car. The 3-D view holds the car in its recorded attitude with the suspension linkage moving. Two arrows under the car show where the front wheels point and where the car is really going, and they split apart under understeer. Tyre marks are left wherever a tyre scrubbed, blue when the front washes wide and red when the rear steps out.
  3. Read the map. The driven line is coloured for braking, coasting and power, and thickens with speed. A rail beside it flags understeer and oversteer. You can add the average of your laps, the best possible composite line, or the line AC's own AI drives.
  4. Compare the channels. The graphs plot the game's data against the model's, all sharing one cursor with the map and the car.
  5. Check what the car is doing. A live readout names every state that holds at the cursor (understeering, oversteering, sliding, spinning, off the road), and pop-ups mark the moments the car left the road, came back onto it or hit something.

The model

Every setup starts from Assetto Corsa's own car files: mass, wheelbase, track, weight distribution, springs, anti-roll bars, dampers, tyre grip and load sensitivity, aero and gearing. It can then be fitted to a real lap from the telemetry.

Change a setup and Try on this lap replays the same lap through both versions, on the same line at the same speed. You see what the change would have done to roll, load transfer, suspension travel and camber.

What it won't do

ACST is a calibration tool, not an oracle.

What am I looking at?

ACST replays laps you drove in Assetto Corsa and shows where you were quick and where you lost time. The screen reads top to bottom; these steps follow it in that order.

  1. A session is one visit to the track. Open the list with Sessions (or press O) and click one: it opens on your first clean lap.

    Try: open any session.

  2. Along the top: speed, gear, lap time and steering, big enough to read during playback. The sector chips are coloured against your best. On the right, Show picks which panels are on screen.

  3. Your lap played back exactly as driven, suspension, loads and tyres included. Three cameras sit over the picture:

    • Chase: behind the car, turning with it.
    • Orbit: drag to walk round it, scroll to zoom.
    • Cockpit: the driver’s seat, with the wheel, pedals and dash moving as you drove.

    Double-click the view to come back to Chase.

  4. The bar under the car: ▶ plays, the slider scrubs, and the speed buttons slow it to ¼× for a corner. Repeat chooses what happens at the flag: the whole session again, or just this lap.

    Try: press ▶, then drag the slider.

  5. The track from above. Colours show braking (red), coasting (yellow) and accelerating (green). Click to jump to a spot. Shift+click twice to mark a stretch (A to B) and study just that.

  6. On the left, every lap of the session with its time. Your best is in gold; the bar is the gap to it. Click a lap to open it, ▸ to see its sectors and corners.

    Try: click + Compare on another lap to draw it next to this one.

  7. Under the playback bar, three panes:

    • Car setup with the pit engineer under it: the car’s settings, and plain advice.
    • Ideal line & braking: your best sectors stitched into one lap, and where you brake against it.
    • Model fit: how closely the app’s model of the car follows the game, so you know how far to trust it.

  8. Speed, pedals, steering and suspension over the lap. Orange is this lap, blue the main lap you measure against. Hover a graph to read the values; the car and map follow.

  9. The Garage tab puts the car on a lift with the lid open. Change camber, toe, roll stiffness and pressure and watch the wheels move; slide the suspension through its travel; read what each change is good for. Then drive it, or save it as a file for AC.

  10. The Drive tab lets you drive the car yourself with help: it follows the ideal line, and the closer you keep to it, the faster you go. Hold ↑ for throttle and steer.

Hover over any button to see what it does.