OTK Genuine 50mm KZ Rear Axle

The OTK Genuine 50mm KZ rear axle is a genuine 1030mm replacement and setup axle for compatible OTK-based gearbox kart chassis. Available in multiple hardness options, it is ideal for KZ race preparation, chassis setup and replacing worn or damaged axles.

Sourced directly from OTK, this is a genuine manufacturer component designed for KZ and gearbox kart applications on compatible OTK-based chassis. Whether you are replacing a worn or damaged axle ahead of a race weekend, fine-tuning rear-end grip and handling balance, or preparing a spare chassis for testing, this axle is a reliable, competition-ready choice for KZ racers, mechanics and teams running compatible OTK-based machinery.

Rear axle selection is one of the most important chassis setup decisions on a KZ kart. The stiffness of the axle directly affects how the rear of the kart behaves through corners, under braking and on corner exit. KZ and gearbox karts place significant load through the rear axle due to gear changes, braking force and engine torque, making axle choice particularly important for both performance and consistency. A harder axle tends to reduce rear flex, which can improve stability and suit higher-grip circuits, heavier drivers or conditions where the kart is already generating strong rear traction. Softer options allow more chassis movement, which can help the kart work in lower-grip conditions or on circuits where rear-end rotation is needed.

Key features:

• Genuine OTK KZ rear axle — not an aftermarket or pattern part
• 50mm diameter, designed for OTK-based KZ chassis using a 50mm rear axle specification
• Length: 1030mm
• OTK item number: 0054.H0
• Available in multiple hardness options depending on variant
• Designed for KZ 125cc gearbox kart applications
• Suitable for compatible OTK-based KZ chassis including Tony Kart, Kosmic, Exprit and LN Kart
• Sold individually

Variant guide:

• Type U — Extra Soft: For very low-grip conditions or circuits requiring maximum rear-end rotation
• Type Q — Soft: For lower-grip conditions where additional chassis movement is beneficial
• Type N — Medium: Standard factory baseline, suitable for a wide range of conditions
• Type H — Hard: For higher-grip circuits or conditions where rear stability is the priority
• Type HH — Extra Hard: For high-grip circuits, heavier drivers or where maximum rear stiffness is required
• Type HD — Extra Extra Hard: For the highest-grip conditions or specific setup requirements

Setup note:

Axle hardness has a direct effect on KZ kart handling. A harder axle generally reduces rear flex and suits high-grip conditions, heavier drivers or circuits where stability and drive off corners is the priority. A softer axle allows more chassis movement and can help the kart generate rear grip and rotation in lower-traction conditions. On KZ karts, axle choice also influences braking stability and behaviour under gear changes. Always select your axle based on circuit conditions, class requirements, driver weight and setup advice from your team or mechanic.

Product details:

• Brand: OTK (genuine part)
• OTK item number: 0054.H0
• Diameter: 50mm
• Length: 1030mm
• Application: KZ / gearbox / shifter kart
• Hardness options: Extra Soft (U) / Soft (Q) / Medium (N) / Hard (H) / Extra Hard (HH) / Extra Extra Hard (HD)
• Sold individually
• Axle keys, bearings, hubs, sprocket carriers and other fittings are not included

Compatibility note:

This axle is designed for compatible OTK-based KZ gearbox kart chassis using a 50mm x 1030mm rear axle. It is commonly used on the following chassis:

• Tony Kart
• Kosmic
• Exprit
• LN Kart
• EOS
• Red Speed

Before ordering, please confirm your chassis model, axle diameter, axle length, brake hub, sprocket carrier, wheel hub and bearing carrier compatibility. This axle is not a universal fit and is intended only for compatible OTK-based KZ chassis using the 50mm x 1030mm rear axle specification.

Ideal for:

• Replacing a worn or damaged KZ rear axle on an OTK-based chassis
• KZ chassis setup and rear-end grip adjustment
• Race preparation and testing on gearbox kart applications
• KZ mechanics and race teams managing multiple chassis
• Owner-drivers maintaining or setting up their own KZ kart
• Competitive KZ karting across a range of circuits and conditions

A genuine OTK component, built to the correct specification for competitive KZ karting on compatible OTK-based gearbox kart chassis.