Ready to step up from Driver’s Class? Box Stock is the next level, offering faster speeds and a few additional tuning and modification options as racers become more comfortable behind the wheel. While still keeping modifications limited, drivers have more freedom to fine-tune their cars while continuing to develop their driving skills and racecraft.
It’s the perfect progression for drivers who have mastered the basics and are ready for more speed, more tuning, and closer competition!
Chassis:
Kyosho MR-04 RWD Chassis Only
Allowed Wheelbases: RWD 90mm, 94mm, 98mm and 102mm
No added weight allowed
Electronics:
Car Must be in full-speed mode
Unmodified Kyosho MZ9P or MZ9E Motor from RWD RTR Sets must be used
Stock ESC Board must be used
EasyLap Transponder must be used
Stock transmitter from RTR Set must be used
Permitted Modifications:
20 gauge motor wire allowed
OK to remove safety switch from motor
OK to change steering wheel on remote
Not Allowed:
Built-In or Separate Gyro
Gear Ratio:
6t to 9t Pinion (Included with RTR Kits)
Stock Kyosho Gear Diff Only
Permitted Modifications:
Gear Diff Grease allowed
Wheels:
All brand plastic and aluminum 1/28 scale production wheels allowed
Size Limitations:
Maximum Front wheel width: 8.5mm (excluding outer flange/disk.)
Maximum Rear wheel width: 8.5mm (excluding outer flange/disk.)
Wheel Diameter: 19-20mm
Wheels must fit inside the body
Tires:
Rubber tires only
Maximum tire diameter (mounted): 25.5mm
Maximum front tire width: 8.5mm
Maximum rear tire width: 11mm
Tires may be cleaned with 70% alcohol solution or water
Not allowed:
Tire additive or traction compound
Tire Warmers
Homemade tires
Batteries:
Cars must be powered by 4 AAA batteries
Ni-MH or Ni-Cd cell-type only
Body & Wing:
Any manufactured molded hard shell that fits the allowed wheelbase
Permitted Modifications:
Front splitter may be shaved to reduce the chances of snagging on track barriers
Standard rear wing for corresponding body may be used with no height limit
Custom aftermarket plastic wings must meet 45mm height limit from ground
Not Allowed:
Lexan windows/roof
Shaving/thinning body material for weight reduction
Permitted Option Parts:
Aluminum 0° front knuckles
Delrin front pivot balls
Ball Bearings
T-Plates
Front and Center Springs
Aluminum wheel nuts