Removable Pinion 12d. M50 ø7.5mm in Brass

Removable brass pinion for precise transmission adjustment

The pinion is one of the most influential components in the behaviour of a slot car: it determines the gear ratio, affects acceleration, and defines how the motor responds in each section of the track. This removable brass pinion with 12 teeth, module 50, and an outer diameter of 7.5 mm, secured with an M2.5 mm screw, offers a simple and robust solution for mounting and dismounting the transmission without complications.

Technical specifications

• Reference: SC-1072A75
• Number of teeth: 12
• Module: 50
• Outer diameter: 7.5 mm
• Axle diameter: 2 mm
• Fixing: M2.5 mm screw
• Material: brass
• Type: removable

Function and performance

Brass is a classic material in slot transmissions for several reasons: it offers very precise machining of the teeth, works well with plastic or delrin crowns without excessive wear, and withstands long running sessions without deforming. Being removable and secured with a screw, changing the pinion is quick and does not require removing the axle from the chassis: simply loosen the screw, remove the pinion, and install the new one, which greatly facilitates preparation work at the club or at home.

With 12 teeth and module 50, this pinion is commonly used in gear ratio combinations aimed at tracks with long straights or high torque motors, where a slightly longer development is sought to take advantage of top speed without sacrificing response on corner exit.

Compatibility and installation

This pinion is designed for 2 mm diameter axles, a very common measurement in competition slot chassis. Before installing it, it is advisable to check that the module 50 teeth are compatible with the crown you already have installed, as module 50 and module 48 are not interchangeable even though they may appear similar at first glance. Once compatibility is verified, the tightening of the M2.5 screw should be firm but not excessive to avoid damaging the axle or compromising the centring of the pinion.

Common mistakes

• Mixing modules: pairing an M50 pinion with an M48 crown (or vice versa) results in poor meshing, noise, and premature wear. Always check that the pinion and crown share the same module.
• Excessive screw tightening: overtightening can mark the axle and hinder future disassemblies, or even misalign the pinion. Adjust firmly and check the free rotation before putting the car on the track.
• Not checking the gear play: a small adjustment in the position of the motor or axle can make the difference between a quiet and efficient transmission or a noisy drivetrain with power losses.

Frequently asked questions

Which crowns is this pinion compatible with?

As it is module 50, it must be combined with crowns also of module 50. It is not compatible with crowns of module 48 or other modules, even if the dimensional differences are small.

What advantage does brass have over other materials?

Brass offers very precise tooth machining, good durability in continuous use, and smooth behaviour with plastic or delrin crowns, which are the most common in slot cars. It is a balanced option between performance and longevity.

Can I use this pinion in a car with anglewinder motorisation?

Yes, as long as the motor axle is 2 mm and the installed crown is module 50. The motor geometry (sidewinder, inline, or anglewinder) does not affect the compatibility of the pinion, which depends solely on the axle diameter and the module.

How tight should the M2.5 fixing screw be?

The tightening should be sufficient to prevent the pinion from rotating on the axle under load, but without forcing. A precision screwdriver or an Allen key suitable for the size of the screw is sufficient; it is neither necessary nor recommended to use high-torque tools.

Do I need any special tools to install it?

No. A suitable Allen key or precision screwdriver for the M2.5 screw size is all that is needed. The removable pinion feature makes it easy to install and uninstall quickly without the need for a press or special tools.

The SC-1072A75 is a 12-tooth brass pinion gear, module 50, 7.5 mm outer diameter, designed for 2 mm axles and secured with an M2.5 screw. A reliable and easy-to-swap transmission component for slot car racing enthusiasts looking to fine-tune gear ratios on club or home tracks.