Tech Inspection Q&A
Tech Inspection Q&A
Real questions racers have asked about Alpha Cup 2026 rules, answered by class. Read this before you build so there are no surprises at the inspection table.
Box Stock Q&A
The level playing field. Race the kit as it comes. If it didn't come in your box, it doesn't race.
Can I mix and match rollers, like putting a stock FM-A roller on an AR chassis?
No. Box Stock means you race what came in your kit. An FM-A roller is not part of an AR kit, so it counts as an outside part. Not permitted.
Can I use different colored rollers if they're meant for the same chassis?
No. Even if the roller fits your chassis perfectly, a separately bought colored roller is still an outside part. If it didn't come in your box, it can't race. This keeps inspection simple and fair for everyone.
Can I use a different cowl, like a Shadow Shark cowl on an AR Avante or a VZ cowl on an S2 kit?
No. The kit-supplied body is the body you race. Swapping cowls between kits is not allowed in Box Stock.
I want more car variety so it isn't all Mach Frames. What can I do?
Bring a different kit. In Box Stock the variety comes from the kit you choose and how clean you build it, not from adding outside parts. There are plenty of kits out there to stand out with.
Can I race Box Stock and also enter BMAX or Open?
Yes, for Alpha Cup 2026 only. Since we have a smaller group and racers traveling from far, we are allowing cross-entry this time.
BMAX Q&A
Aligned with official Tamiya race regulations. More freedom than Box Stock, with clear body and chassis limits.
Can I run a polycarbonate (clear) body?
Yes. Both plastic and polycarbonate bodies are permitted, aligned with official Tamiya regulations. Poly bodies must be fully painted and stickered, and secured with body catches front and rear.
Does my body have to match the chassis it came with?
No. Any Tamiya body, plastic or poly, can run on any legal Tamiya chassis. It just has to mount securely with body catches front and rear. Trimming to fit is allowed within 3mm of any interference point, as long as the original body shape stays recognizable.
Can I run CNC machined or anodized rollers in BMAX?
No. CNC machining and anodizing are not allowed in BMAX. Those are permitted in Open class only. BMAX uses Tamiya rollers in their standard form.
What happens if my body or wing falls off during a race?
If the body or wing detaches during a race, the car is disqualified from that heat. An animal figure falling off is also an immediate DQ. Secure everything before you run.
Open Q&A
The builder's class. Chassis cutting, weight reduction, ball bearings, and full tuning are all on the table. Tamiya, R/C Mini 4WD, and Dangun Racer parts only.
Can I run CNC machined or anodized rollers in Open?
Yes. For Alpha Cup 2026, CNC machining and anodizing of Tamiya rollers are allowed in Open class. This is a MiniMod adaptation of the Tamiya Open regs for this event. Rollers must still be Tamiya originals.
Can I cut my chassis or shave parts for weight?
Yes, within limits. You may cut plastic away or cut holes in the stock chassis, and shave gears or parts to reduce weight. The original part shape must stay clearly identifiable, and the molded chassis markings (MS, MS-L, N-01, T-01, etc.) must remain.
Can I install ball bearings, including in the gears?
Yes. Ball bearings are allowed in Open, including installed in gears. All running gears must still follow the set gear ratios.
What battery do I use in Open?
AA NiMH only, 1900mAh max, same as the rest of Alpha Cup. No modified or tampered batteries. Note this differs from some Tamiya Open events that require alkaline. At Alpha Cup it is NiMH across all classes.