OTK Genuine 50mm KZ Rear Axle

The gearbox classes place higher demands on the rear axle than direct-drive categories — the additional torque and different power delivery characteristics of a gearbox engine require a stiffer axle specification to maintain chassis balance and prevent excessive rear movement under acceleration. The 0054H0 is the genuine OTK 50mm KZ specification rear axle, available in a range of hardness grades and designed for OTK Group chassis running KZ, KZ2, or DD2 class engines.

Key Specifications

• Part Number: 0054H0
• Diameter: 50mm
• Length: 1030mm
• Class: KZ / KZ2 / DD2
• Sold individually — keys, bearings, and hubs not included

Hardness Grades

Grades run from softest to hardest.

• U — Extra Soft
• Q — Soft
• N — Medium
• H — Hard
• HH — Extra Hard
• HD — Extra Extra Hard

Compatibility

Tony Kart

• Racer 401 RR (KZ)
• Racer 401 TDX (KZ)

Kosmic

• Mercury RR (KZ)
• Mercury TDX (KZ)

Exprit

• Noesis RR (KZ)
• Noesis TDX (KZ)

LN Kart

• LN Four (KZ)
• LN Four TDX (KZ)

Redspeed

• RX RR (KZ)
• RX TDX (KZ)

Other OTK Group

• CS55 MY2025 (KZ)
• EOS (KZ)
• Gillard TG17 (KZ)

The KZ axle (0054H0) uses a different specification to the OK axle (0054G0) and the two should not be interchanged between classes. When replacing, inspect the brake disc carrier, sprocket hub, and bearing carriers for wear and correct seating on the replacement axle. Axle keys should also be checked and replaced if worn.

Workshop Tip: KZ axles are subjected to greater torsional loads than direct-drive axles. Check for straightness and any signs of stress marks near the keyways after impacts or particularly aggressive runs. A bent or cracked axle should be replaced immediately — never straightened and refitted.