MiniMod SD Alpha Cup 2026 Official Rules

Official Race Format & Rules

MiniMod SD Alpha Cup 2026

Read this first before race day. The goal is simple: clear rules, fair racing, beginner-friendly flow, and no confusion at check-in.

View Schedule View Classes Box Stock Rules BMAX Gear Rules BMAX Body Rules Open Class Rules
Important: Organizer decisions are final. Any rule not explicitly permitted is prohibited. Cars may be inspected at any time.
Date
June 20, 2026
Escondido, California
Racer Fee
$5 Registration
Limited to 50 racers
Classes
Box Stock, BMAX, Open
Apex runs before each class
Battery Limit
AA NiMH, 1900mAh Max
No modified batteries
Start Here

Participant Information

Keep this section visible so racers understand the basics fast.

Agreement
  • By registering, all racers agree to follow all rules.
  • Any rule not explicitly permitted is prohibited.
  • Organizer decisions are final.
Registration
  • $5 registration fee.
  • Limited to 50 racers.
  • Non-refundable once finalized.
Who Can Race
  • All racers may compete in BMAX and Open.
  • Box Stock is the beginner-friendly entry class.
  • Race fair. Help the next racer.
Main Classes

Class Overview

This gives racers a quick snapshot before they read the deeper rules.

Box Stock

Best entry point for newer racers who want a simple, fair race format.

BMAX

Competitive Tamiya-style racing with multiple car entries and impound rules.

Open

Higher-level builds with the same entry flow and impound structure as BMAX.

Equipment Rules

Batteries, Motors, and Tech

These rules help keep racing safe, fair, and easy to inspect.

Battery Rules
  • AA NiMH only.
  • Maximum 1900mAh.
  • No modified batteries.
  • Organizer may reject unsafe batteries.
Motor Rules
  • Tamiya motors only.
  • Motors must remain sealed.
  • No motor modifications.
Technical Rules
  • Follow Tamiya standards.
  • No magnets.
  • No track-damaging setups.
  • Cars may be inspected any time.
Race Format

How Each Class Works

Clear race flow reduces confusion at check-in and during staging.

Box Stock Format
  • 25-minute practice before racing.
  • 1 car per racer.
  • No battery changes once racing begins.
  • Winning cars are impounded immediately.
  • No rebuy round for Box Stock.
BMAX and Open Format
  • 25-minute practice before racing.
  • Max 4 cars per racer.
  • $5 per car.
  • Winning cars are impounded. Batteries may be removed, recharged, or swapped between heats.
  • Cars are independent entries.
Car Usage Rules
  • Cars may be reused only after a loss.
  • Winning cars are locked and cannot be reused.
  • Once a car wins, it stays impounded.
Rebuy Rounds
  • Applies to BMAX and Open only.
  • Occurs after Round 1 if time permits.
  • Max 2 additional car entries.
  • Cars must not have won any race.
  • Winning cars cannot be reused.
Race Conduct
  • No assisted starts.
  • No touching cars after release.
  • Car off track equals loss.
Beginner-Friendly Class

Box Stock Rules

Race your car as it comes out of the box. No outside parts, no upgrades, no modifications. If it didn't come in your kit, it doesn't race.

⚡ The level playing field.
Box Stock follows Tamiya guidelines and the established Box Stock community standard. The point is fair racing and a fast, clean tech inspection. Variety comes from the kit you choose, not from mixing parts.
Eligibility
  • 1 car per racer.
  • For Alpha Cup 2026 only, Box Stock racers may also enter BMAX and Open.
  • Basic Mini 4WD kits only.
  • No Special Edition kits with Grade-Up option motors.
  • No Starter Packs or Advanced Pack Special kits.
The Car
  • Built per the kit instruction manual.
  • Kit-supplied parts only. No outside parts.
  • No mixing parts from other kits.
  • Kit-supplied body and motor only.
  • Driver figure must be used if included.
  • Underside plastic brake must stay on if included.
Batteries
  • AA NiMH only. 1900mAh max.
  • No modified or tampered batteries.
  • Organizer may reject unsafe batteries.
  • No battery changes once racing begins.
Box Stock Build Rules
Allowed
  • Kit-supplied rollers in kit-supplied positions
  • Moving rollers only to alternate holes already built into your chassis
  • Painting the body (optional)
  • Applying the kit stickers
  • Choosing not to install every body part
  • Lubricants on plastic bushing parts
  • Any Tamiya Mini 4WD grease on gears and roller screws
Not Allowed
  • Outside rollers, different sizes, or separately bought colored rollers
  • Swapping cowls or bodies between kits
  • Bearings, FRP, carbon plates, or any option/upgrade parts
  • Motor changes, tuning, or modifications
  • Chassis cutting, shaving, sanding, or new holes
  • Weight reduction of any part, chassis, or body
  • Tire cutting, sanding, gluing, or surface treatment
  • Cutting or drilling the body
On car variety: Box Stock will see a lot of the same chassis, and that's fine. The fair way to stand out is the kit you pick and how clean you build it, not by adding parts that didn't come in the box. Bring a different kit if you want a different look.
Inspection and enforcement: Cars may be inspected at any time. Bring your box and instructions in case of a dispute. Violations may result in disqualification. Organizer decisions are final.
BMAX / Stock Class

Gear Rules

These rules are listed clearly because gear confusion causes problems fast.

FM-A Chassis
  • FM-A chassis cars must use the official black 8T pinion gear.
  • Only Tamiya-compatible FM-A gear sets are allowed.
  • Mixed or modified gears are not permitted.
FM / Super FM Chassis
  • FM and Super FM chassis must use the proper Special 3.5:1 gear set designed for those chassis.
  • Incorrect gear combinations or mixed gear setups are not allowed.
  • Only Tamiya gear configurations intended for the chassis may be used.
General Gear Rule
  • All gears must remain unmodified.
  • Cutting, shaving, polishing for performance alteration, or custom tooth modifications are prohibited.
  • Tamiya OEM gears only.
Inspection and enforcement: Cars may be inspected any time. Violations may result in disqualification. Organizer decisions are final.
BMAX Class — Aligned with Tamiya USA

Body Rules

Polycarbonate bodies are permitted for BMAX at the SD Alpha Cup 2026, per official Tamiya regulations.

⚡ Polycarbonate (clear) bodies are allowed in BMAX.
Aligned with official Tamiya race regulations at tamiya.com. Both plastic and polycarbonate bodies are permitted. All bodies must be painted or stickered and secured with body catches front and rear.
Plastic & Polycarbonate Body Rules
Allowed
  • Plastic bodies
  • Polycarbonate (clear) bodies — must be fully painted and stickered
  • Any Tamiya body on any legal Tamiya chassis — no kit matching required
  • Painting the body any color or custom livery
  • Applying stickers or decals
  • Mixing body and wing from different kits
  • Attaching wings or spoilers with adhesive
  • Trimming within 3mm of any contact point with chassis, plate, damper, or tires
  • Removing canopy to fit an animal figure (must be secured with tape or glue)
  • Cutting sections and inserting mesh (original shape must remain recognizable)
Not Allowed
  • Unpainted polycarbonate body
  • Polycarbonate body without stickers
  • PET bodies
  • Homemade or 3D printed bodies
  • Splitting the body into separate pieces
  • Trimming beyond 3mm from any interference point
  • Excessive trimming making the original shape unrecognizable
  • Repairing trimmed areas with adhesive or filler
  • Body or wing detaching during a race — immediate DQ
  • Animal figure falling off during a race — immediate DQ
Cross-Chassis Rule (per Tamiya official regs): No requirement for a body or cowl to match its original kit chassis. Any Tamiya body — plastic or polycarbonate — can be run on any legal Tamiya chassis. It just needs to mount securely with body catches front and rear. Trimming to fit a different chassis is allowed within 3mm of any interference point, as long as the original body shape is still recognizable.
Required on ALL bodies: Body catches secured at BOTH front and rear. If the body comes off during a race, the car is disqualified from that heat. Polycarbonate bodies that are difficult to verify as painted or stickered may be rejected at tech inspection.

Chassis Rules

Allowed
  • Applying stickers to the chassis
  • Expanding standard screw holes by up to 2mm
  • Drilling through non-penetrated standard screw holes
  • Countersinking existing screw holes
Not Allowed
  • Cutting, trimming, or shaving the chassis
  • Adding new screw holes
  • Reversing chassis orientation
  • Custom or homemade chassis
  • Painting the chassis
Inspection and enforcement: Cars may be inspected at any time. Body violations discovered during a race result in disqualification from that heat. Organizer decisions are final.
Top-Level Builds

Open Class Rules

The fastest, most modified class at Alpha Cup. Built on official Tamiya Open regulations with MiniMod adaptations for this event.

⚡ This is 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. If a modification isn't listed, race officials have final authority.
Car Specs
  • Four-wheel drive only.
  • Max width 105mm, height 70mm, length 165mm.
  • Minimum ground clearance 1mm.
  • Minimum weight 90g with battery and motor.
  • Tires: diameter 22-35mm, width 8-26mm.
Battery & Motor
  • AA NiMH only. 1900mAh max.
  • No modified or tampered batteries.
  • Tamiya motors only, matched to your chassis.
  • No motor disassembly or terminal tampering.
  • Signs of cap removal mean instant DQ.
Rollers & Dampers
  • Unlimited rollers.
  • Tamiya rollers only.
  • CNC machining and anodizing allowed for Open.
  • Mass damper weight must sit inside the line between front and rear guide roller axes.
Open Class Modifications
Allowed
  • Cutting plastic away or cutting holes in the stock chassis
  • Tamiya, R/C Mini 4WD, and Dangun Racer parts
  • Cutting or drilling parts as long as the original shape stays identifiable
  • Ball bearings, including installing them in gears
  • Gear holes or shaving to reduce weight (set gear ratios must be kept)
  • Opening holes or painting the top side of rollers
  • CNC machining and anodizing of Tamiya rollers
  • Combining different tire sizes or materials
  • Cutting or shaping tires within legal dimensions
  • Kit or Grade-Up battery terminals per the manual
Not Allowed
  • Homemade chassis or homemade parts
  • Modifying part shape so the original is unidentifiable
  • Removing the molded chassis markings (MS, MS-L, N-01, T-01, etc.)
  • Prohibited roller combos (foreign plastic rings, mixed-material roller surfaces)
  • Changing tire surface material, adhesives, or coatings
  • Soldering or double-plated battery terminals
  • Motor disassembly, rewinding, or terminal tampering
  • Sharp or hazardous shapes that damage the track or cause injury
  • Leaving grease or substances on the track
  • Homemade or non-Tamiya parts of any kind
Forbidden zone: Parts may not extend past the outer edge of the tire between the front wheel center axis and the rear of the front wheel, or between the rear wheel center axis and the front of the rear wheel. Bodies and high-mounted rollers above the tire center axis are exempt.
Inspection and enforcement: All cars are inspected before racing. No setting changes between inspection and racing. Re-inspection can happen any time. Parts found out of spec during re-inspection void all records to that point. Organizer decisions are final.
Apex Run Events

BMAX Apex and Open Apex

High-stakes side events run before each class's main racing begins.

Apex Run Format

Cars are locked in before racing begins. Racers submit cars with batteries installed before the race. Once submitted, cars are impounded immediately.

Event Classes
  • BMAX Apex — runs before BMAX Racing.
  • Open Apex — runs before Open Racing.
  • $20 per car.
  • Maximum 2 cars.
Apex Rules
  • Cars submitted with batteries before race.
  • Impounded immediately.
  • No battery changes.
  • 70% winner and 30% organizer split.
Race Day

Schedule

Schedule may be adjusted to stay on time.

Important

Time Rule

  • All racing must be completed by 8:00 PM.
  • Final hour, 8:00 PM to 9:00 PM, is reserved for teardown and cleanup.
  • Schedule may be adjusted to stay on time.
9:00 AM

Setup

Track setup, table setup, check-in prep, and event staging.

10:00 AM

Registration and Check-In

Racers check in and confirm entries before class racing begins.

10:30 AM

Box Stock Practice

10:30 AM to 10:55 AM. Practice window is 25 minutes.

11:00 AM

Box Stock Racing

Racing begins.

12:00 PM

Box Stock Awards

Awards presented immediately after Box Stock racing concludes.

12:10 PM

BMAX Practice

12:10 PM to 12:35 PM. Practice window is 25 minutes.

12:40 PM

BMAX Apex Run

High-stakes side event. Cars submitted with batteries and impounded before racing begins.

1:10 PM

BMAX Racing

  • Racing begins.
  • After Round 1: rebuy round if time permits.
3:00 PM

BMAX Awards

Awards presented immediately after BMAX racing concludes.

3:10 PM

Open Practice

3:10 PM to 3:35 PM. Practice window is 25 minutes.

3:40 PM

Open Apex Run

High-stakes side event. Cars submitted with batteries and impounded before racing begins.

4:10 PM

Open Racing

  • Racing begins.
  • After Round 1: rebuy round if time permits.
6:00 PM

Open Awards

Awards presented immediately after Open racing concludes.

6:15 PM

Final Buffer

Overflow buffer for delays, extended races, or schedule adjustments.

7:00 PM

Racing Complete

All racing must be complete.

8:00 PM

Teardown and Cleanup

Teardown and cleanup run from 8:00 PM to 9:00 PM.

MiniMod Garage | San Diego, California