# Anti-dive, anti-squat and anti-lift

> How side-view suspension geometry resists pitch under braking and acceleration. The anti-dive formula from the side-view instant center, inboard versus outboard brakes, and a worked example (12.6 percent anti-dive) on the opensus Formula SAE example.

Anti-dive, anti-lift and anti-squat are the share of a pitch load transfer that the suspension links carry instead of the springs. 100 % anti-dive means the front doesn't compress at all under braking; 0 % means the springs take all of it. They come from the side-view geometry of the suspension.

| Name | Axle | When |
|---|---|---|
| Anti-dive | Front | Braking |
| Anti-lift | Rear | Braking |
| Anti-lift | Front | Accelerating (front-wheel drive) |
| Anti-squat | Rear | Accelerating |

## Formula

In the side view, the upright rotates about its **side-view instant center** (SVIC). Draw a line from the point where the longitudinal force acts to the SVIC, at angle \(\theta\) above the ground. For the front axle under braking, with wheelbase \(L\), CG height \(h\) and front brake share \(b\):

$$\text{anti-dive} = \tan\theta \times \frac{L}{h} \times b \times 100\ \%$$

The point the force acts at depends on where the torque is reacted:

- **Outboard brakes** (caliper on the upright): the braking force acts at the **contact patch**.
- **Inboard brakes or drive** (torque reacted by the chassis through a driveshaft): it acts at the **wheel center**, so the line starts there, and the same geometry gives much less anti.

The rear uses the rear brake or drive share and a line pointing forward. Tick **Inboard brakes** or **Inboard drive** under **Tires and unsprung** to tell opensus which applies.

## Worked example: Formula SAE front

The [Formula SAE example](/docs/examples/fsae/) has a 1550 mm wheelbase, a 290 mm CG, 62 % front brake bias and outboard front brakes. opensus finds the front side-view instant center 6196 mm behind the contact patch and 235.1 mm above the ground:

$$\tan\theta = \frac{235.1}{6196} = 0.0380$$

$$\text{anti-dive} = 0.0380 \times \frac{1550}{290} \times 0.62 \times 100 = 12.6\ \%$$

That matches the readout's **Anti-dive / lift** value of 12.6 %. The rear of the same car has 13.5 % anti-lift in braking and about 0 % anti-squat, because its drive is inboard and its side-view line through the wheel center is nearly flat.

## Design notes

- **Inclining the arm pivot axes in side view** moves the SVIC up or down and sets the anti. Tilting both front arms' pivot axes so they converge behind the wheel adds anti-dive.
- **Too much anti** stiffens the suspension over braking bumps and changes caster as the wheel travels; 10 to 30 % is common on race cars.
- **Above 100 %** the car would rise under braking.

**Kinematics → Heave** plots **Anti-dive / anti-lift** across travel, and **View → Pitch centre and force lines** in the 3D view draws the side-view lines.

[Open in opensus](https://opensus.app/app/?example=fsae)

Source: https://opensus.app/docs/anti-dive-anti-squat/ (last updated 2026-11-07)