Crown gear 35d. Sidewinder M50 for axle 2.38mm O18.5mm screw M2.5

The Scaleauto SC-1145R Crown Gear: Millimetric Precision for Your Sidewinder Transmission in 1/32

When adjusting the transmission of a slot car, every tenth counts. This 35-tooth crown gear from Scaleauto is specifically designed for Sidewinder configurations —motor positioned parallel to the rear axle— and is part of the high-precision spare parts programme that the Valencian brand maintains for the 1/32 scale.

Technical Specifications

• Number of Teeth: 35 t.
• Module: M50
• Outer Diameter: Ø 18.5 mm
• Compatible Axle Diameter: 2.38 mm
• Fixing: M2.5 screw
• Reference: SC-1145R
• Motor Configuration: Sidewinder (motor parallel to the rear axle)
• Scale: 1/32

Function and Performance

The crown gear is the final link in the kinematic chain: it receives the motion from the motor pinion and transmits it directly to the rear axle. With 35 teeth and module M50, this reference offers an appropriate gear reduction ratio for medium-high performance motors on Sport track layouts, such as those commonly used by Scaleauto. The diameter of Ø18.5 mm places it in a balanced range: sufficient to absorb torque without adding unnecessary weight to the rear end.

The M2.5 screw fixing ensures a firm fit on the 2.38 mm axle, preventing slippage under load that would penalise acceleration response and consistency from lap to lap.

Compatibility and Installation

This crown gear is designed for a 2.38 mm axle, a common measurement in Scaleauto kits and chassis for 1/32. Before installation, it is advisable to verify:

• That the motor pinion also has module M50 to ensure correct meshing.
• That the centre distance (rear axle – motor axle) is compatible with the outer diameter of 18.5 mm.
• The condition of the M2.5 fixing screw: a worn screw can cause play during racing.

Preparation and Common Errors

A common mistake when replacing a crown gear is not checking the backlash. A gear mesh that is too tight generates heat and premature wear; too loose produces vibration and loss of traction. The usual reference is to feel a slight play when moving the crown gear with your finger, but without rattling. Apply a minimal amount of specific slot gear grease to the flanks of the teeth to extend the lifespan of both the crown gear and the pinion.

Another point to watch: ensure that the crown gear is perfectly centred with respect to the pinion in the axial plane. A lateral misalignment, even by tenths, accelerates wear and can cause the crown gear to skip under hard acceleration.

Ideal for…

This crown gear fits particularly well in club and amateur competition setups where a measured gear ratio is sought for technical or medium-speed circuits. The Sidewinder configuration, combined with a 35-tooth crown gear, allows for good weight distribution on the rear end and maintains guide load during braking.

Frequently Asked Questions

Which pinions is this crown gear compatible with?

It must be combined with pinions of module M50. The number of teeth on the pinion will determine the final gear ratio; consult Scaleauto's reduction tables to choose the most suitable combination for your motor and circuit.

Can I use this crown gear in an Inline or Anglewinder configuration?

No. This crown gear is specifically designed for Sidewinder setups, where the motor is positioned parallel to the rear axle. Different geometries and references are required for Inline or Anglewinder configurations.

Is the M2.5 fixing screw included with the crown gear?

The product description indicates that the fixing screw is M2.5. We recommend confirming the exact contents of the blister upon receiving the product or consulting us before placing your order.

When should I change the crown gear?

When the teeth show visible wear (rounded or asymmetrical flanks), when there is abnormal vibration in the transmission, or when the meshing produces metallic noise even if the backlash is correct. In club competition, periodic inspection between sessions is good practice.

Is it valid for Sport track and Universal track?

The crown gear is an internal component of the car and does not depend on the type of track. It works on any track as long as the car chassis is compatible with this Scaleauto reference.

The Scaleauto SC-1145R is a 35-tooth sidewinder crown gear, module M50, designed for 2.38 mm axles with an outer diameter of 18.5 mm and M2.5 set screw fixing. A precision replacement part for 1/32 scale slot car builds, ideal for club racing and performance tuning on Sport track layouts. Compatible with Scaleauto chassis and kits requiring M50 module gearing.