B-MAX

A no-cut tuning class using genuine parts and bolt-on systems.

CLASS PHILOSOPHY

Maximize setup quality while preserving the original form of the chassis and tuning parts.

✅ ALLOWED

→Genuine Tamiya chassis used in its intended direction without cutting or hollowing.
→Genuine Tamiya plastic, FRP, carbon and aluminum plates installed through existing holes.
→Countersinking existing chassis and plate holes without creating new attachment holes.
→Wheel-shaft piercing through the existing wheel bore.
→Genuine Tamiya rollers, bearings, shafts, brakes, mass dampers, stabilizers and sliding-damper sets.
→Trimming brake sponge, Mini 4WD tape and rubber tube to the required installation size.
→Plastic or polycarbonate bodies trimmed only for fitment and interference clearance.
→All motors marked legal for B-Max in the club motor matrix.

⚠️ ALLOWED WITH CONDITIONS

→Sliding dampers must use their intended genuine components and remain securely mounted.
→Body cutting must preserve a recognizable body and may not create a suspended-body or moving-body damping system.
→Plates may be stacked or bonded but may not be reshaped, tapered, drilled or cut.
→Parts that can touch the course wall must be fixed, except normal wheels, rollers, mass dampers and sliding-damper motion.

❌ NOT ALLOWED

→Cutting, hollowing, reversing, heating or reshaping the chassis.
→Cutting, drilling, sanding, tapering or reshaping FRP, carbon, aluminum or roller parts.
→Tire sanding, shaving, truing, stretching or chemical treatment.
→Changing roller diameter, machining rollers, replacing roller bearings or altering plastic rings.
→Floating gears, modified gears, custom gear clamps or altered gear ratios.
→Chouchin, hikuo, norio, catcher-damper, anchor, AT/pivot or other custom moving systems not supplied as a legal bolt-on set.
→Homemade, copied, third-party or 3D-printed components installed on the race car.

SCRUTINEERING

CLASS INSPECTION

1No chassis or plate cutting and no added holes

2Genuine unmodified rollers, gears and tuning components

3Legal motor and chassis-compatible gear ratio

4Tires and wheels not processed beyond allowed wheel piercing

5No prohibited moving gimmick or homemade component

6Secure screws, covered shafts, body attachment and full measurements

OFFICIAL DECISION

Rulebook v1.0 applies from 30 July 2026. A configuration not explicitly described must be shown to the race director before inspection. Approval at one event does not automatically create a permanent rule.

VIEW MOTOR MATRIX OPEN BUILD GUIDES