Mini-Z Pinion Gear Ratio Reference: 6T to 11T by Chassis and Use Case

Gear ratio is one of those tuning variables that gets less attention than it deserves in Mini-Z circles. People obsess over tire compound and spring rate, then run whatever pinion gear came in the car and wonder why it feels slightly off at the top end, or why the motor runs warm after a session on RCP.

The pinion size you run changes the mechanical gear ratio between your motor and your rear spur gear. That determines how fast your motor spins relative to the wheels — and therefore how the car feels at different points in the throttle range. It also determines how hard your motor works, which directly affects heat and battery consumption.

This guide gives you the reference table first, then a short explanation of how to read it and when to change your pinion.

How Mini-Z Gearing Works

All current Mini-Z platforms use a fixed spur gear on the rear axle. The motor drives a pinion gear that meshes with the spur. Gear ratio is calculated as:

Gear Ratio = Spur Teeth / Pinion Teeth

Larger pinion = lower numerical ratio = more top speed, harder on the motor. Smaller pinion = higher numerical ratio = more torque, better acceleration, cooler motor.

The stock spur gear on most Mini-Z platforms is 43T. Some aftermarket setups run different spur sizes, but for this reference table, 43T is the baseline.

On brushed motors, a stock N10 motor draws heat quickly if you’re overdriving it with too large a pinion. On brushless, the KV rating of your motor interacts with the pinion — a 10,000 KV motor on an 11T pinion is a different animal than the same motor on an 8T.

Kyosho Aluminum Pinion Gear Set AWD (MDW021)

For broader pinion selection beyond the Kyosho aluminum set, search Mini-Z pinion gears on Amazon — most hobby-grade pinions in 6T-11T live there or through direct vendors like RCMart and Atomic.

Mini-Z Pinion Gear Ratio Reference Table

The table below assumes a 43T spur gear, which is standard across MR-03, MR-04, and MA-020 platforms. MX-01 uses the same motor mount format but gearing is separate (see the MX-01 row notes). Gear ratio listed is the final mechanical ratio (spur/pinion).

Pinion	Ratio (43T spur)	MR-03	MR-04	MA-020	MX-01	Best Use Case
6T	7.17:1	Stock brushed, beginner	Stock brushed, beginner	Not recommended	Crawler/trail	Maximum torque, minimum speed. Crawler and ultra-low-speed driving only on MX-01.
7T	6.14:1	Stock class, RCP	Stock class, RCP	Stock brushed, RCP	Crawler/trail	Standard starting point for brushed stock racing on MR-03 and MR-04. Good for RCP carpet.
8T	5.38:1	Brushed mod class, brushless low-KV	Brushed mod class	Stock grip racing	Not standard	Sweet spot for MA-020 grip racing on RCP. On MR-03, works well with brushless under 10,000 KV.
9T	4.78:1	Brushless mid-KV, carpet	Brushless, fast carpet	Brushless grip, fast drivers	Not standard	Brushless territory on all RWD platforms. Good for smooth indoor carpet tracks with consistent surfaces.
10T	4.30:1	Brushless high-KV, smooth RCP	Brushless, experienced only	Brushless high-power	Not standard	High-speed builds. Motor runs hotter. Use with quality bearings and ESC timing dialed in.
11T	3.91:1	Outdoor/large venue	Specialist/outdoor	Large outdoor tracks	N/A	Maximum top speed. Rarely useful on club-size RCP layouts. Motor heat becomes a real management concern.

Reading the Table

A 7T pinion at 6.14:1 means your spur gear rotates once for every 6.14 motor revolutions. Higher ratio = motor spins more relative to wheel speed = more torque, more heat, lower top speed. Lower ratio (bigger pinion) = motor spins fewer times per wheel revolution = higher top speed, more motor demand.

For RCP track racing — the most common Mini-Z competitive context — 7T or 8T is where most setups live on stock and mod brushed classes. Brushless setups typically start at 8T-9T and go from there based on the motor’s KV rating and the track layout.

Platform-Specific Notes

MR-03: The MR-03 is the most widely raced Mini-Z platform. For RCP club racing in stock brushed class, 7T is the default. Once you move to brushless via the Brushless Conversion guide, 8T-9T covers most RCP layouts. On outdoor or larger tracks, 10T becomes worth trying if your motor can handle the heat.

MR-04: The MR-04’s narrower chassis and lighter feel means it responds well to the same pinion range as the MR-03. However, because the car already rotates aggressively, a larger pinion that increases top speed can make it harder to drive on tight tracks — you’re adding another variable to manage. Start conservative (7T-8T) and work up. For more on the MR-04 setup philosophy, see the MR-04 Platform Guide.

MA-020: AWD drivetrain has more internal friction than RWD. That means the motor works harder at any given pinion size compared to an equivalent RWD setup. Running a smaller pinion (7T-8T) keeps motor temps manageable and preserves acceleration feel. Most MA-020 grip racing setups on RCP are in the 8T range for stock brushed and 9T for brushless. Going to 10T on MA-020 requires a quality ESC with proper thermal management. See the MA-020 Platform Guide for drivetrain context.

MX-01: The MX-01 is a crawler/off-road platform and operates in a different gear ratio world. The table above is not a useful reference for MX-01 performance tuning — the MX-01 runs its own reduction gearing internally and smaller pinions are standard. See the MX-01 Crawler Guide for platform-specific tuning.

Why Gear Ratio Matters More Than People Think

On a Mini-Z, the motor and ESC are running at high RPM in a small enclosed body. Heat buildup is real and it degrades motor brushes, affects ESC behavior, and shortens battery runtime.

Running a pinion that’s too large for your motor and track combination means:

• The motor spins harder on every straightaway
• ESC current draw increases
• Battery depletes faster
• Motor runs hot, which affects consistency over a 5-minute run

Running a pinion that’s too small means:

• You leave top speed on the table
• The car can feel sluggish on longer straights
• On a tight track, it doesn’t matter much — on an open layout, it costs time

The right pinion is the one where your motor runs warm but not hot after a full session, and the car feels responsive without needing to spin the wheels to accelerate. If you’re burning through brushes or running the car slower than the competition on the same motor, check your pinion before anything else.

Beginners typically run whatever ships with the car (usually 7T-8T) and don’t touch it. Fast drivers adjust pinion based on the track layout — a tight technical track with short straights gets a smaller pinion than an open layout with long runs.

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For motor upgrade context that directly affects pinion selection, see the MA-020 Motor Upgrade Guide for AWD-specific guidance and the Brushless Conversion guide for RWD platform brushless builds.

-- MiniZ Modder