Super II Chassis Tuning Guide
Super-II is a rear-motor chassis, the direct successor to the original Super-1, and it is easy to underrate next to newer double-shaft platforms like MS or ME. It shouldn't be. Tamiya's own chassis catalogue lists it as carrying "a reinforced bumper, rear stay secured by 2 rotating switches and screw-secured cover" over the Super-1 it replaced — a durability upgrade aimed at racing, not display building. Super-II kits race under the "Super Mini 4WD" machine type named directly in Tamiya's official regulations, so a correctly built Super-II is legal at any event running the standard rulebook. This guide covers its published dimensions, where it sits inside the official rules, which modifications are and aren't allowed, and a build-and-tune order that keeps a Super-II finishing races instead of just looking fast on a bench.
Super-II chassis at a glance
Tamiya's published figures for the stock Super-II chassis — treat them as a baseline, since added parts (rollers, stays, weights, a different motor) change the finished car's total weight and height.
| Spec | Value |
|---|---|
| Chassis length | 150mm |
| Chassis width | 97mm |
| Wheelbase | 80mm |
| Tread | 64mm |
| Chassis weight | 115g |
| Ground clearance | 5.3mm |
| Stock gear ratio | 4.2:1 |
| Motor format | Single-shaft, rear-motor layout |
| Predecessor | Super-1 chassis |
The single-shaft layout matters most before you buy anything: Super-II uses the standard single-shaft motor family and a propeller shaft to the front wheels, not the double-shaft PRO motors built for MS, MA and ME cars. Buying a motor by name without checking that split is the single most common wasted purchase for a first-time Super-II builder — see the motor guide for the full standard-versus-PRO comparison first.
Where Super-II sits in the official rules
Tamiya's official race regulations name the machine types allowed on an official course, including Racing Mini 4WD, Super Mini 4WD, Fully-Cowled Mini 4WD, Aero Mini 4WD and Mini 4WD PRO. Super-II kits sell under the Super Mini 4WD banner, so the chassis itself is not the issue at inspection — how it's been modified is. The car still has to clear the same dimensional and weight limits as every other class:
| Limit | Value |
|---|---|
| Maximum width | 105mm |
| Maximum height | 70mm |
| Maximum length | 165mm |
| Minimum ground clearance | 1mm |
| Minimum weight (with motor and batteries) | 90g |
| Tyre diameter | 22–35mm |
| Tyre width | 8–26mm |
| Batteries | Tamiya-branded AA (R6/UM3) only |
A stock 115g Super-II chassis, before body and electronics, already sits above the 90g floor and well inside the 5.3mm-versus-1mm clearance window, so there's real margin to lighten the car if your track rewards it — but that margin is only useful once you know what cutting is actually legal, which is class-dependent (see below). Race officials retain final, on-the-day authority to disqualify a non-conforming car or announce special rules, so treat this table as a baseline check, not a substitute for reading the current official regulations before entering anything. The rules and technical inspection checklist walks through what an inspector actually measures.
What you're actually allowed to change
Under the general regulations, permitted modifications include cutting plastic chassis material and drilling gears to remove weight — cutting or reshaping tyres is not permitted — while homemade chassis are banned outright, but modifying a genuine Super-II that way is legal. That changes under Stock Class rules: cutting or shaving the chassis, new screw holes, and reversing the chassis direction are all disallowed. Stock Class still allows body shaving, countersinking holes already present in FRP or carbon plates, cementing plates together, ball bearings, and mixed tyre/wheel sizes, plus a "forbidden zone" between the front and rear axle centrelines where nothing but the body and driver figure may sit — a rear-stay roller tower mounted too far inboard is a common way to fail that check. Only genuine Tamiya Mini 4WD, R/C Mini 4WD and Dangun Racer parts may be added under Stock Class. None of this is interchangeable with a locally organised class like BMAX; confirm which rulebook applies before cutting anything, and check both R1 and R2 directly, since organiser rules and on-day inspection prevail over any guide.
Build a dependable baseline before you tune
A Super-II that finishes every heat beats a lighter one that doesn't, and most DNFs trace back to build quality rather than chassis choice. Start with the gearbox: seat the gear cover fully and check nothing binds when spinning the wheels by hand, since a rear-motor gearbox under load finds any misalignment quickly. Confirm left and right roller heights match — asymmetry here is what actually causes a car to pull toward one wall, more often than the chassis itself. Check that the brake sponge contacts the track evenly across its width before assuming a brake problem is a material or angle issue. Only once that baseline is solid is it worth reaching for the roller guide, brake guide or mass damper guide — chasing rollers or dampers before the drivetrain is sound just moves the same fault elsewhere on the car.
Tuning the Super-II for your track
The stock 4.2:1 gear ratio is a middle-ground reference, not a fixed setting — Tamiya sells gear sets in other ratios for rear-motor chassis, and which suits your Super-II depends on motor choice and course layout more than any single "best" number. Motor selection follows the standard-chassis ladder, not the PRO ladder; the motor and gear ratio matching guide and gear set compatibility guide cover pairing the two instead of guessing. Log what you change and where you tested it — a setup for a tight, technical layout can be wrong for a long straight course. Weighing Super-II against other options for a new build? The chassis compatibility list and Super Mini 4WD series guide cover how it compares.
Frequently asked questions
Can I fit a PRO double-shaft motor in a Super-II chassis?
No. Super-II is single-shaft and drives the front wheels through a propeller shaft; PRO motors are double-shaft units built for chassis like MS, MA and ME that have no propeller shaft. The two families are not physically interchangeable — check your chassis type before buying a motor by name.
Is chassis cutting legal on a Super-II for competition?
It depends on the class. Under Tamiya's general regulations, cutting plastic chassis material is permitted. Under Stock Class rules specifically, cutting or shaving the chassis is not allowed at all, and a locally organised class such as BMAX sets its own rules again. Confirm which rulebook a given event runs before cutting anything — on-day technical inspection is the final word.
Why does the Super-II have a reinforced bumper compared to the Super-1?
Tamiya's chassis documentation describes Super-II as the next generation of the Super-1, adding a reinforced bumper and a rear stay secured by two rotating switches with a screw-secured cover — durability changes for repeated wall and jump contact, not cosmetic updates.