Barbaro Racing KD4123 RS-652 front brake pads for BMW M2 and BMW M G-chassis M2 / M3 / M4 calipers. RS-652 is Barbaro's extreme hybrid race compound for steel and carbon-ceramic rotors (50–800°C, μ 0.49–0.57 on steel). Interchanges with FMSI D2478.

Specifications

Caliper fitment

Vehicle fitment

Fitment is compiled from the Barbaro Racing application catalogue and Barbaro factory data, together with the vehicle listings of the interchange part numbers below. Brake packages can differ within one model — please compare your current pads with the dimensions and drawing, or send us your VIN, before ordering.

Cross-reference / interchange numbers

Interchange numbers identify the matching pad shape. Friction material, shims and wear-sensor hardware can differ between brands.

About the RS-652 compound

RS-652 · The extreme hybrid

Seven years in the making. Endurance and sprint on both carbon-ceramic and steel rotors with zero fall-off, protected by a self-renewing 1–3 micron transfer film. Average friction 0.555 μ — measured beyond PAGID RSL1 (0.510) and Endless MA45B (0.438).

• Temperature range: 50–800°C
• Friction: μ 0.49–0.57 (steel); rising with temperature on CCB
• Discs: Steel + carbon-ceramic
• Lock threshold: 95 bar (RS-635: 65 bar)
• +46.1% lock threshold — 95 bar vs 65 bar
• On CCB, friction rises with temperature — 0.689 μ at 800°C
• Disc wear 0.001 mm — 1/9 of RSL1, 1/18 of MA45B
• Ideal for: TCR, GT and touring-car racing on steel or carbon-ceramic discs

RS-652 full specifications on barbaro-racing.com

About Barbaro Racing

Barbaro Racing (野蛮人) is the performance brand of the CAC Racing Division — proprietary compounds developed entirely in-house. Development begins on the dynamometer and ends on the circuit: every friction formula is bench-tested to destruction before earning the right to carry the Barbaro name. All compounds are validated against GB5763-2018 national standards; Street Series compounds are asbestos-free.