Glossary
What is Rake? Definition, How to Measure It & Aero Effects
Rake is the angle of the car's floor relative to the ground, created by running the rear ride height higher than the front. It is quoted as a ride height difference in millimetres or as an angle in degrees. More rake moves the aerodynamic centre of pressure forward, increases underbody downforce on most cars and shifts the mechanical balance slightly towards oversteer.
| Car type | Typical rake | Primary reason |
|---|---|---|
| Formula car | 20–45 mm (0.5°–1.0°) | Underbody and diffuser performance |
| GT / sports car | 10–25 mm | Aero balance and splitter height |
| Touring / production | 0–15 mm | Mechanical balance and ride |
| Speedway sedan | 20–60 mm | Weight jacking and rear grip on dirt |
Aero effect of rake
Tilting the floor nose-down turns the whole underbody into a shallow diffuser. Air accelerates under the lower front and expands towards the higher rear, lowering pressure under the car. On cars with a rear diffuser, rake increases the effective expansion ratio and moves the centre of pressure forward, so adding rake usually cures aero understeer.
Past a certain angle the flow separates and downforce collapses, which is why cars run skid blocks and why ride height sensors are so valuable.
Mechanical effect of rake
Raising the rear ride height raises the rear roll centre and the rear of the centre of gravity, which increases rear load transfer in corners. It also shifts a small amount of static weight forward. On a non-aero car rake is mostly a way to fine-tune front-to-rear balance after springs and bars are set.
Frequently asked questions
How do I convert rake in millimetres to degrees?
Divide the ride height difference by the wheelbase and take the arctangent. For a 2,600 mm wheelbase, 30 mm of rake is about 0.66°.
Does more rake always mean more downforce?
No. Each floor and diffuser has a stall point. Beyond it the flow separates and downforce drops sharply. Wind tunnel or straight-line ride height sweeps find that limit.
Can I run negative rake?
It is rare. Negative rake (front higher than rear) kills underbody downforce and raises the front roll centre. Some front-wheel-drive cars run close to flat to protect front traction.
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