Crown/pinion 27/10 EXTRALIGHT EVO3

NSR Extralight EVO3 Transmission: The Crown/Pinion Set That Makes a Difference on Track

NSR is one of the leading brands in competitive slot racing when it comes to spare parts and transmission sets. The Extralight EVO3 line represents the third evolution of its ultra-thin crown/pinion, designed to minimise rotating mass and achieve a more direct response from the motor to the rear axle.

Function and Performance

The 27/10 crown/pinion set defines a gear ratio of 2.7:1, placing it in a high top-speed range, particularly suited for fast tracks with long straights or for high-revving motors. The designation Extralight refers to the reduction of material in the tooth geometry and the body of the crown, which decreases rotational inertia and allows the motor to reach its power band more swiftly.

The EVO3 generation incorporates NSR's accumulated improvements in gear geometry, manufacturing tolerances, and wear resistance compared to previous versions, offering a quieter and more durable gear during intensive running sessions.

Compatibility

This set is designed for the standard transmission systems of NSR. To confirm exact compatibility with your chassis, motor, and bracket, we recommend consulting the NSR spare parts catalogue or contacting us: at Ministry of Hobby, we have specialised technicians who can guide you on the optimal combination for your setup.

Assembly and Preparation

To get the most out of the Extralight EVO3 set, pay attention to these points during assembly:

• Check the backlash before permanently securing the crown. A too-tight adjustment generates heat and premature wear; too loose introduces vibration and loss of efficiency.
• Apply a minimal amount of lubricant specifically for slot gears on the tooth flanks. Excess lubricant attracts dirt and can contaminate the tyres.
• Check the alignment of the pinion with the motor before the first run. Even minimal misalignment multiplies wear in very few sessions.
• Inspect the condition of the set after each racing session; being an Extralight part, wear is noticeable sooner than with standard crowns of greater mass.

Common Mistakes

One of the most common mistakes when working with ultralight transmission sets is forcing the pinion onto the motor shaft without verifying the exact diameter. Another common error is mixing different EVO generations (EVO2 with EVO3, for example) when the tooth profile has evolved between versions, which can compromise the meshing. Always use pairs of the same reference and generation.

Ideal for…

This set is particularly suitable for:

• Club competitors looking to save grams on the moving parts of the transmission.
• Tuners working with high-rev motors who need a gear ratio aimed at top speed.
• Advanced hobbyists who already master the assembly and tuning of transmissions and want to explore the improvements of the EVO3 evolution.

Frequently Asked Questions

What is the difference between the EVO3 version and previous generations of Extralight?

NSR has refined the tooth geometry, dimensional tolerances, and materials of the Extralight series in each generation. The EVO3 is the most recent and generally offers a quieter gear and a longer lifespan than the EVO1 and EVO2. For maximum performance, it is recommended to use pinion and crown from the same generation.

What is the exact gear ratio of a 27/10 set?

The ratio is calculated by dividing the number of teeth on the crown by that of the pinion: 27 ÷ 10 = 2.7:1. This means the motor turns 2.7 times for each complete turn of the rear axle, resulting in higher top speed compared to shorter ratios.

Do I need to replace the crown and pinion together, or can they be changed separately?

Technically, they can be replaced separately, but if one of the two shows noticeable wear, it is common among tuners to change the complete set. Mixing a heavily worn part with a new one creates irregular meshing that accelerates the deterioration of both.

What lubricant do you recommend for the Extralight EVO3 transmission?

The most common practice is to use specific slot gear lubricants in minimal quantity. Apply a small drop on the tooth flanks and let the car run for a few seconds before cleaning off the excess. Avoid high-viscosity oils or general-purpose lubricants not specific to the hobby.

Is it compatible with motors from other brands mounted on NSR chassis?

Compatibility depends on the diameter of the pinion shaft and the chassis bracket system. If you mount a motor from another brand on an NSR chassis, check that the shaft diameter matches the pinion included in this set before attempting the installation.

The NSR Extralight EVO3 27/10 crown and pinion set (ref. NSR6702EVO3) is a high-performance slot car transmission component designed for competitive racing and advanced tuning. With a 2.7:1 gear ratio and third-generation Extralight engineering, it delivers reduced rotational inertia and improved gear mesh precision. An ideal upgrade for NSR chassis builds, club racing setups, and experienced hobbyists seeking marginal gains in slot car performance.