48mm x 3/32 Calibrated Axle CN CHRONO 2 pcs

Millimetric precision in every assembly: CN SRC calibrated axles for competition slot

The axle is one of those components that, when well chosen, goes unnoticed — and when poorly chosen, it is evident everywhere. These CN calibrated axles from SRC are manufactured using a carbo-nitriding process, a thermochemical treatment that hardens the surface of the steel to achieve a hardness of 60Rw, providing the axle with superior wear resistance without losing the dimensional precision required for prepared slot racing.

Technical specifications

• Pack contents: 2 CN calibrated axles (carbo-nitrided)
• Diameter: 3/32" (2.38 mm)
• Length: 48 mm
• Length tolerance: +0.05 mm
• Hardness: 60Rw
• Treatment: Carbo-nitrided (CN)

Function and performance

A calibrated axle serves a critical function in the rear end of a slot car: transmitting the motor torque to the wheels with minimal play and maximum concentricity. The precise calibration of the diameter at 2.38 mm ensures a correct fit with the pinions, crown gears, and wheels designed for the 3/32" standard, while the controlled tolerance of +0.05 mm in length facilitates assembly without the need for additional machining.

The hardness of 60Rw achieved through carbo-nitriding means that the surface of the axle better resists the abrasion generated by continuous use, the tightening of the pinions, and positional adjustments with Allen screws — a common wear point in conventional axles of lower hardness.

Compatibility and assembly

The 3/32" diameter is the most widespread in the world of prepared slot racing, compatible with a wide variety of chassis and drivetrain groups. The 48 mm length places it within an appropriate range for many competition and prepared chassis, although it is advisable to always verify the length required by the specific chassis before proceeding with the assembly.

Common mistakes to avoid

One of the most common mistakes when working with calibrated axles is applying excessive force when pressing pinions or crown gears without first checking the concentricity. A high hardness axle like this tolerates mechanical work well, but the precision of the assembly also depends on the condition of the tools used and the extraction/insertion support employed. We recommend always using a suitable pinion puller and checking the free rotation of the assembly before final assembly.

Frequently asked questions

What is the difference between a calibrated axle and a standard axle?

A calibrated axle is machined with very tight dimensional tolerances, ensuring a uniform diameter throughout its length and a precise fit with the drivetrain components. A standard axle may exhibit variations that result in vibrations, play, or accelerated wear.

What does CN (carbo-nitrided) mean?

Carbo-nitriding is a thermochemical surface hardening treatment that introduces carbon and nitrogen into the outer layer of steel. The result is a harder and more wear-resistant surface, while maintaining a tougher core that better absorbs mechanical stresses.

What type of chassis is this axle designed for?

The 3/32" diameter is compatible with the vast majority of prepared and competition chassis in the slot market. The 48 mm length is specific for certain configurations; always check your chassis specifications to confirm it is the correct measurement.

Does the pack include 2 ready-to-mount units?

Yes, the pack contains 2 CN calibrated axles, as indicated by the reference SRCRM0209. Both units have the same dimensional and hardness specifications.

Is any additional treatment required before assembly?

Generally no, although some preparers apply a light layer of lubricant at the axle support points on the bench. The CN treatment already provides the necessary surface hardness without requiring additional hardening steps.

The SRC SRCRM0209 is a pack of 2 carbo-nitrided (CN) calibrated axles in 3/32" diameter (2.38 mm) and 48 mm length, featuring 60Rw hardness and +0.05 mm length tolerance. Designed for slot car racing and competition preparation, these precision axles ensure optimal drivetrain performance and long-lasting durability. Compatible with most 3/32" slot car chassis setups.