Removable pinion 12d. M50 ø7.0mm in Ergal for axle

Ergal, module 50 and clean extraction: this is the SC-1072E70 pinion from Scaleauto

When fine-tuning a drivetrain for competition, every gram and every tenth of a millimetre counts. The removable Scaleauto SC-1072E70 pinion meets this requirement with a clear proposal: 12 teeth, module 50, axle hole ø7.0 mm and a machined body in Ergal, the 7075 aluminium alloy that the aerospace industry and competitive modelling have made a reference material due to its balance between lightness and hardness.

Function and performance

The pinion is the direct link between the motor and the crown gear, and its geometry defines the final gear ratio of the car. With 12 teeth and module 50, this pinion fits with M50 crowns of the same system, offering a suitable gear ratio for technical circuits and medium-high speed.

The Ergal reduces rotating weight compared to brass or steel pinions, resulting in a livelier motor response when exiting corners and less inertia when braking. For those seeking maximum performance without sacrificing durability, it is a coherent choice.

The removable design facilitates assembly and disassembly without aggressive tools that could damage the axle or pinion, something appreciated by any preparer who changes gear ratios between sessions or tracks.

Compatibility

This pinion is designed for 2 mm axles, the most widely used standard diameter in the vast majority of slot racing setups. The module 50 (M50) must match the module of the crown it pairs with: mixing different modules generates play, noise, and premature wear, so it is advisable to always verify that the crown and pinion share the same module.

It is compatible with sidewinder (motor parallel to the rear axle) and inline (motor in line with the rear axle) setups, depending on the chassis configuration. The choice of the number of teeth on the pinion relative to the crown will determine the top speed and acceleration of the assembly.

Assembly and preparation

• Ensure the axle is clean and free of burrs before inserting the pinion to guarantee a proper fit.
• Check the alignment between pinion and crown: a slight misalignment multiplies wear and generates vibrations.
• The Ergal tolerates continuous use well, but avoid excessive tightening of the fixing screw that could deform the hole.
• To calculate the gear ratio, divide the number of teeth on the crown by those on the pinion. With this 12-tooth pinion and a crown of, for example, 27, you obtain a ratio of 2.25:1.

Common mistakes

• Mixing modules: a M50 pinion does not work correctly with an M48 or M64 crown. Incorrect meshing wears both parts in a few sessions.
• Not checking lateral play: a small amount of play between pinion and crown is necessary, but excess causes noise and loss of efficiency.
• Ignoring axle balancing: if the pinion is not centred on the axle, vibrations will clearly be noticeable on track.

Frequently asked questions

What real advantage does Ergal offer over brass in a pinion?

Ergal (7075 aluminium alloy) is significantly lighter than brass, which reduces the mass in rotation. This improves motor response and decreases inertia, something particularly noticeable on circuits with many curves and frequent acceleration changes.

Which crowns is this pinion compatible with?

With any crown of module 50 (M50) designed for the same transmission system. The module must match between pinion and crown for correct meshing.

Is this pinion suitable for 3/32" axles?

No. This pinion has an axle hole of ø7.0 mm and is specified for 2 mm axles. For 3/32" (2.38 mm) axles, a pinion with the corresponding axle diameter would be necessary.

Is it valid for inline and sidewinder configurations?

Yes. The pinion itself is compatible with both motor configurations. What changes between an inline and a sidewinder setup is the position of the motor relative to the axle, not the pinion itself, as long as the crown and module are appropriate.

What gear ratio do I get with this pinion?

It depends on the number of teeth of the crown you combine it with. The ratio is calculated by dividing the teeth of the crown by those of the pinion (12). A 27-tooth crown would give a ratio of 2.25:1; a 30-tooth crown, 2.5:1. The higher the ratio, the more acceleration and lower top speed.

Do I need any special tools to mount it?

No special tools are required beyond a suitable screwdriver for the fixing screw. Being removable, the assembly and disassembly process is straightforward and does not require press tools or heat.

The Scaleauto SC-1072E70 is a 12-tooth M50 module removable pinion gear machined in Ergal (7075 aluminium alloy) for 2mm axles, designed for slot car competition setups. Lightweight and precise, it delivers fast throttle response and reduced rotational inertia, making it a top choice for club racers and performance-oriented builders seeking reliable drivetrain components compatible with sidewinder and inline motor configurations.