9d pinion M50 steel for 2mm axle ø5.5mm x 2mm

Tuned Transmission: Scaleauto 9-Tooth Steel Pinion for 2 mm Axle

The pinion is one of the smallest components of the drivetrain and, at the same time, one of the most influential on the car's behaviour. The SC-1129B55 from Scaleauto is a 9-tooth pinion made of steel, designed to fit 2 mm diameter axles, with an outer diameter of 5.5 mm and a width of 2 mm.

Technical Specifications

• Number of teeth: 9
• Material: steel
• Axle diameter: 2 mm
• Outer diameter: 5.5 mm
• Width: 2 mm
• Reference: SC-1129B55
• Brand: Scaleauto

Function and Performance

In a slot car's transmission, the pinion is the gear that connects the motor to the crown gear and, ultimately, to the rear wheels. The choice of the number of teeth on the pinion —along with the crown gear— determines the gear ratio: a 9-tooth pinion combined with a crown gear of a higher tooth count provides more torque and acceleration out of corners, at the cost of a slightly lower top speed. This is a common setup on technical tracks with many slow corners or on short Sport track layouts where control on corner exit makes a difference.

The use of steel as a material ensures significantly higher durability compared to plastic or resin pinions, especially when working with higher power motors or during long training and competition sessions. Wear is minimal, and the engagement with the crown gear is clean and consistent, resulting in smooth transmission without unwanted play.

Compatibility and Installation

This pinion is designed for 2 mm axles, the most widely used standard in 1/32 scale slot racing. It is compatible with the usual Scaleauto mounts and any chassis that uses a 2 mm rear axle. To ensure proper fixation, it is recommended to check that the fit on the axle is secure and, if the pinion design allows, apply a small drop of thread-locking adhesive or axle fixative to prevent movement during the race.

When adjusting the fit with the crown gear, attention must be paid to the tooth clearance: neither too tight —which would generate friction and heat— nor with excessive play —which would cause vibrations and power loss—. A sheet of 80 g paper between the pinion and crown gear is the classic reference for calibrating that clearance accurately.

Common Mistakes When Installing a Pinion

• Mounting the pinion off-centre relative to the axle, causing vibrations and uneven wear on the crown gear.
• Not checking the lateral alignment between the pinion and crown gear before securing the motor.
• Using a worn pinion without visually inspecting it: teeth with burrs or irregularities generate noise and loss of efficiency.
• Mixing very dissimilar materials (steel pinion with soft plastic crown) without considering that steel can wear the crown more quickly.

Frequently Asked Questions

Which crown gears is this pinion compatible with?

As a standard module pinion for 1/32 slot, it is compatible with the usual crowns of that module. Check the specifications of the crown you use to ensure that the module matches that of this pinion.

Why choose steel over other materials?

Steel offers greater wear resistance and better torque transmission, especially with powerful motors. It is the usual choice in competition and serious tuning compared to plastic pinions, which deform or wear out sooner.

What gear ratio do I get with 9 teeth?

It depends on the number of teeth on the crown gear you combine it with. A lower pinion/crown ratio provides more torque and acceleration; a higher ratio gives more top speed. With 9 teeth on the pinion, a 27-tooth crown gives a 3:1 ratio, oriented towards traction and recovery.

Is it necessary to lubricate the pinion?

A light lubrication at the contact point between the pinion and crown gear improves durability and reduces noise. Use a specific slot grease in very small amounts: excess attracts dirt and can affect performance.

Is this pinion suitable for sidewinder, inline, or anglewinder configurations?

Yes, the pinion itself is independent of the motor configuration. What varies according to the configuration (sidewinder, inline, anglewinder) is the motor position and, therefore, the angle of attack on the crown gear, but the pinion is mounted on the motor axle in any of the three cases.

The Scaleauto SC-1129B55 is a 9-tooth steel pinion gear for 2 mm axles, featuring a 5.5 mm outer diameter and 2 mm width. Designed for 1/32 slot car racing, it delivers reliable and precise power transmission, making it a go-to choice for club racers and serious hobbyists looking to fine-tune their drivetrain setup.