15-tooth pinion. Diameter 7.5mm. Ergal

Pure Ergal: the Slot.it 15-tooth pinion for those who push every straight

The SIPI7515E is the 15-tooth pinion with a diameter of 7.5 mm that Slot.it manufactures in Ergal, the high-strength aluminium alloy that combines remarkable hardness with a very low weight. Within the Ergal 1/32 spare parts range, this component occupies the long end of the gear ratios: fewer crown gear revolutions per pinion revolution, more top speed on the straights.

Function and performance

The main advantage of Ergal over brass —the usual material in standard pinions— is the drastic reduction of rotational mass on the motor shaft. With less inertia to manage, the motor responds more nimbly when accelerating and the assembly brakes more effectively, as there is less kinetic energy to dissipate. The result is a more reactive behaviour and a more stable dynamic balance throughout the session.

The 15 teeth define a long gear ratio: the motor turns more revolutions to move the rear axle the same distance, resulting in higher maximum speed. It is the natural choice for circuits with very long straights where the car needs to stretch its rev range to the maximum.

Compatibility and installation

With a diameter of 7.5 mm, this pinion fits Sidewinder (motor parallel to the rear axle) and Anglewinder (motor angled relative to the rear axle) configurations that use large diameter crowns. Like the rest of the Slot.it range, the precision machining ensures smooth gearing, with minimal mechanical noise and a constant power transmission to the rear axle.

Before installing any pinion, it is advisable to check that the centre distance between pinion and crown is correct for the recommended flank play. An assembly with too much pressure causes premature wear; with too much play, loss of efficiency and noise.

Installation and preparation

• Check the fit of the pinion on the motor shaft before permanently pressing it.
• Verify lateral alignment with the crown to avoid uneven wear.
• Apply a minimal amount of specific slot gear lubricant to the flanks of the teeth.
• With high-performance motors, periodically check the condition of the teeth, especially during intensive running sessions.

Common mistakes

• Choosing 15 teeth on technical circuits with many slow corners: such a long ratio penalises corner exit acceleration. In technical layouts, consider pinions with fewer teeth.
• Not checking diameter compatibility with the motor shaft: always ensure that the inner diameter of the pinion matches the shaft diameter before mounting.
• Excess lubricant: can attract dirt and degrade the rubber of the tyres if it splashes onto the rear axle.

Frequently asked questions

What type of circuit is a 15-tooth pinion most suitable for?

It is the ideal option for tracks with long straights where top speed is the deciding factor. On short or very technical circuits, a shorter ratio (fewer teeth) usually yields better lap times.

What is the difference between an Ergal pinion and a brass one?

Ergal is a much lighter aluminium alloy than brass. This reduction in mass on the motor shaft decreases rotational inertia, resulting in greater responsiveness, better braking, and, in general, a livelier behaviour of the mechanical assembly.

What motor configurations is this pinion compatible with?

It is compatible with Sidewinder and Anglewinder setups that use large diameter crowns. For Inline setups (motor perpendicular to the rear axle), consult the specific specifications of your chassis, as the transmission geometry varies.

Do I need special tools to mount it?

It is recommended to use a pinion press or suitable mounting tool to avoid damaging the motor shaft or the pinion itself during adjustment. A hammer or direct impact can misalign the assembly or damage the motor bearings.

How often should I check the condition of the pinion?

It depends on the intensity of use and the type of motor. With high-performance motors in competition sessions, a visual inspection after each day is sufficient to detect premature wear or play in the gear with the crown.

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