25Z crown gear bronze insert

Tuned transmission for inline motors: the 25Z crown gear from Slot.it with bronze insert

When the goal is to get the most out of an inline setup, every component of the transmission matters. The SIGI25-BZ crown gear from Slot.it concentrates in just a few tenths of a millimetre the engineering work that distinguishes an amateur setup from a serious preparation: 25 teeth, bronze insert, and calibrated pitch for a 2.38 mm axle.

Technical specifications

• Number of teeth: 25Z
• Insert: bronze
• Compatible axle diameter: 2.38 mm
• Motor configuration: inline (motor perpendicular to the rear axle, in line with the car)
• Manufacturer: Slot.it (reference SIGI25-BZ)

Function and performance

The bronze insert is the differential element of this crown gear compared to pure plastic versions. Bronze is a material with excellent wear resistance and low friction on the steel axle, resulting in smoother transmission, less heating during long sessions, and a considerably longer lifespan. For tuners who accumulate many laps on the bench or track, this makes a tangible difference in maintenance.

With 25 teeth, this crown gear is positioned in an intermediate-high reduction range. Combined with the appropriate pinion, it allows for adjusting the balance between corner exit acceleration and top speed according to the layout. It is a common choice on technical circuits where quick response is sought without sacrificing stability on the straights.

Compatibility and installation

This crown gear is designed exclusively for motors mounted in inline configuration: those in which the motor's axle is perpendicular to the rear axle, aligned longitudinally with the car. It should not be confused with the sidewinder arrangement (motor parallel to the rear axle) or the anglewinder (motor at an angle). Using the correct crown gear for each type of motorization is the first step to avoiding alignment and rubbing issues in the transmission.

The axle diameter of 2.38 mm is the most widespread standard in the Slot.it range and in many competition chassis on the market. Before installation, it is advisable to verify that your car's axle corresponds to this measurement and that the axial play is correctly adjusted.

Common mistakes

• Installing an inline crown gear on a sidewinder motor: the angle of attack with the pinion will not be correct and will cause premature wear and loss of efficiency.
• Not checking the axle diameter: a too-loose fit generates lateral play; one that is too tight can block rotation or damage the insert.
• Forcing installation without proper alignment: the bronze insert improves durability, but does not compensate for poor transmission geometry.

Frequently asked questions

What is the difference between a crown gear with a bronze insert and a plastic one?

The bronze insert reduces friction between the crown gear and the axle, improves heat dissipation generated by rotation, and increases the durability of the assembly. It is the preferred option for intensive use and competition.

Is this crown gear compatible with my Slot.it chassis?

If your Slot.it chassis has an inline motor configuration and the rear axle is 2.38 mm, this crown gear is directly compatible. For other manufacturers, always check the axle diameter and motor configuration before installing it.

What pinion should I use with this 25-tooth crown gear?

The choice of pinion depends on the motor, the layout, and the desired driving style. There is no single valid combination: we recommend consulting Slot.it's tuning guides or experimenting on the bench to find the optimal ratio for your setup.

Can I use this crown gear on Scalextric or Ninco track?

The crown gear itself is not limited by the type of track, but by the car's configuration. If the chassis accepts an inline motor and a 2.38 mm axle, it can run on any rail system, including universal rail systems like Scalextric or Ninco.

When should I change the crown gear?

When visible wear on the teeth is observed, excessive play with the pinion, unusual noise in the transmission, or loss of traction without apparent cause in the motor. The bronze insert extends the lifespan, but it is not eternal if operated under heavy load or with little lubrication.

The Slot.it SIGI25-BZ is a 25-tooth inline crown gear with a bronze insert, designed for 2.38 mm axles. A precision slot car transmission component ideal for competitive setups and club racing, offering reduced friction, extended durability, and consistent power transfer in inline motor configurations.