Steel pinion 9t 5.5mm

9-Tooth Steel Pinion for 5.5 mm Inline Transmissions

When fine-tuning the mechanics of a slot car, every component of the transmission matters. This 9-tooth steel pinion with a pitch of 5.5 mm (ref. MB-19250) is designed for setups with the motor in an inline position, meaning the motor is arranged longitudinally and in line with the rear axle, a common configuration in builds aimed at lowering the centre of gravity and increasing traction.

Function and Performance

The pinion is the direct link between the motor and the crown gear: its number of teeth determines the gear ratio and, with it, the balance between acceleration and top speed. A 9-tooth pinion represents a shorter ratio option, favouring response on corner exits and in circuits with many direction changes, especially when combined with larger crown gears.

Manufactured from steel, it offers significantly higher wear resistance compared to plastic or nylon pinions, resulting in a more consistent transmission throughout sessions and less maintenance in the medium term.

Compatibility and Installation

This pinion is designed for inline transmissions with a 5.5 mm pitch. Before installation, it is advisable to verify that the module of the pinion matches that of the crown gear mounted on the rear axle; mixing different modules results in poor meshing, noise, and premature wear on both components.

• Check the inner diameter of the pinion to ensure it fits the output shaft of your motor.
• Verify the alignment between pinion and crown gear before tightening: a slight lateral misalignment can cause vibrations and power loss.
• Apply a minimal amount of special grease for slot transmissions; excess grease attracts dirt and ultimately harms the meshing.

Common Mistakes

• Over-tightening the pinion onto the shaft: this can cause micro-deformations that misalign the component and produce "runout" (eccentricity), penalising the transmission.
• Not verifying the module with the crown gear: even if the 5.5 mm pitch is correct, the module of the teeth must match exactly for proper meshing.
• Ignoring axial play: a small controlled play between pinion and crown gear extends the lifespan of both components; zero play does not equate to greater precision, but rather to increased wear.

Ideal for…

This pinion fits into the workflow of any tuner who adjusts the gear ratio according to the layout: technical and slow circuits benefit from shorter ratios like that offered by a 9-tooth pinion, while fast and long layouts may warrant moving up to 10 or more teeth to gain top speed. Having it in the spare parts kit allows for transmission adjustments between sessions without complications.

Frequently Asked Questions

Which crown gears is this pinion compatible with?

It should be combined with crown gears whose tooth module matches that of this pinion and that are designed for inline transmissions with a 5.5 mm pitch. Check the technical specifications of your crown gear before mounting.

What is the difference between a steel pinion and a nylon one?

Steel offers greater durability and consistency in transmission, especially in long sessions or with high-power motors. Nylon dampens impacts slightly better but wears out more quickly under continuous load.

How does the number of teeth on the pinion affect the car's behaviour?

Fewer teeth on the pinion (while keeping the crown gear) implies a shorter gear ratio: more acceleration and lower top speed. More teeth lengthen the ratio: more top speed but a smoother response from a standstill.

Is it necessary to use grease on the pinion-crown meshing?

Yes, but in very small amounts. A micro-drop of specific grease for slot transmissions is sufficient to reduce wear without attracting dirt or hindering the smoothness of rotation.

Can I use this pinion in a sidewinder configuration?

This pinion is designed for inline transmissions. In a sidewinder setup, the motor is positioned transversely to the rear axle, and the transmissions usually have different geometries and pitches; always verify compatibility before installation.

The MB-19250 is a 9-tooth steel pinion gear for 5.5 mm inline slot car drivetrains. Designed for precision transmission setups, this steel pinion delivers consistent meshing with matching crowns, reduced wear and reliable power transfer from motor to rear axle. A key component for slot car tuners looking to fine-tune gear ratios on technical circuits. Compatible with inline motor configurations; always verify module and bore diameter before fitting.