Aren't plain, undrilled discs the first choice in motorsport?

Often yes. Many pure racing and endurance applications rely on plain, two-piece discs without drillings and with only discreet slotting, because they offer the greatest material reserve and the fewest stress points. Slots and drillings are more of a compromise for road and ambitious track day than a performance gain at the highest level.

Do drilled discs really brake better in the wet?

The effect is small and barely noticeable with modern pads. The drillings stem from an era of outgassing pads - today the compound and slots handle this job better. Anyone who chooses drilled discs does so mainly for looks, not because of measurably shorter braking distances in the rain.

Drilled or slotted brake discs? Comparison for track day

Drilled vs. slotted brake discs: what does it really do?

Slotted two-piece sport brake discs (GiroDisc) - slots instead of drillings for thermal durability

Drilled or slotted brake discs? Drilled discs look the part fast, slots last longer thermally. Both designs have clear pros and cons in coefficient of friction, cracking and service life. What Endless pros recommend for road and track day is summed up in this comparison.

Drilled brake discs: pros and cons

Drilled brake discs help with water drainage and provide a somewhat more stable buildup of friction in the wet. They are lighter and look sporty.

Their downside: stresses form at the edge of the drillings that can lead to cracking under high thermal load. For pure road use this is uncritical, but in hard track day use it is an issue.

Slotted brake discs: pros and cons

Slotted brake discs hold up thermally better because no drillings weaken the disc. The slots scrape the topmost pad layer clear and keep the coefficient of friction constant even under heat.

The price for that: slots are somewhat noisier and pad wear rises slightly. For track day and race track that's a good trade.

Recommendation for road and track day

For pure road use both designs are uncritical - here looks often decide. Anyone who regularly goes on the race track is safer with slotted or two-piece discs because they are thermally more durable.

Frequently asked questions

Aren't plain, undrilled discs the first choice in motorsport?: Often yes. Many pure racing and endurance applications rely on plain, two-piece discs without drillings and with only discreet slotting, because they offer the greatest material reserve and the fewest stress points. Slots and drillings are more of a compromise for road and ambitious track day than a performance gain at the highest level.
Do drilled discs really brake better in the wet?: The effect is small and barely noticeable with modern pads. The drillings stem from an era of outgassing pads - today the compound and slots handle this job better. Anyone who chooses drilled discs does so mainly for looks, not because of measurably shorter braking distances in the rain.

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