Senzo OTK (TonyKart) 50mm Rear Axle
Axles & Axle Spares

Senzo OTK (TonyKart) 50mm Rear Axle

Length Mm / HardnessSKURRP ex VATQty
1000 / Soft / Type QAX50S1000£70.00
1000 / Medium / Type NAX50M1000£70.00
1000 / Hard / Type HAX50H1000£70.00
1030 / Extra Soft / Type UAX50SS1030£80.00
1030 / Soft / Type QAX50S1030£70.00
1030 / Medium SoftAX50M1030-SP£70.00
1030 / Medium / Type NAX50M1030£70.00
1030 / Medium HardAX50M1030-G£70.00
1030 / Hard SoftAX50A1030£70.00
1030 / Hard / Type HAX50H1030£70.00
1040 / Extra Soft / Type UAX50SS£80.00
1040 / Soft / Type QAX50S£80.00
1040 / Medium / Type NAX50M£80.00
1040 / Hard / Type HAX50H£80.00
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The Senzo Rear Axle 50mm OTK is a high-quality aftermarket axle built specifically for OTK-based chassis including Tony Kart, Exprit, Kosmic, Redspeed and Energy. Same fitment as genuine OTK, engineered for strength and consistency, at a sharper price point.

Available in seven stiffness grades — more range than the genuine OTK lineup offers — so you can genuinely dial your setup to conditions rather than just running whatever's already in the kart. Available in 1000mm, 1030mm and 1040mm lengths.

Axle stiffness is one of the most effective tuning tools on a kart. A softer axle flexes more, lifting the inside rear wheel and generating rear grip — ideal when the track is green, cold, or damp. A harder axle limits that flex, reducing grip and preventing the rear from overworking on high-traction surfaces. Get it right and it's worth more than a full day of chassis adjustments.

⭐ Not sure where to start? Go for Medium / Green (Type N) — it's the benchmark grade used by most drivers in dry conditions. Once you know how the kart feels on a medium, you'll know which direction to move.

Axle stiffness scale

Softer — more gripHarder — less grip
Extra SoftSoftMed SoftMediumMed HardHard SoftHard
Extra Soft
Type U
Best for
Wet / damp Cold track Light driver
Rm 300–380 N/mm²
Soft
Type Q
Best for
Low grip Green track Cool / fresh
Rm 350–400 N/mm²
Medium Soft
—
Best for
Between Q & N Slightly soft track
Rm 470–500 N/mm²
Medium ⭐
Type N
Best for
Dry conditions General use Most drivers
Rm 480–550 N/mm²
Medium Hard
—
Best for
Warm track Heavier driver High grip
Rm 500–650 N/mm²
Hard Soft
—
Best for
Very high grip Rubbered-in Competitive use
Rm 650–800 N/mm²
Hard
Type H
Best for
Max grip Hot conditions Aggressive drivers
Rm 800–900 N/mm²

Stiffness by grade (tensile strength Rm)

Extra Soft
300–380 N/mm²
Soft
350–400 N/mm²
Medium Soft
470–500 N/mm²
Medium ⭐
480–550 N/mm²
Medium Hard
500–650 N/mm²
Hard Soft
650–800 N/mm²
Hard
800–900 N/mm²

Key Features

  • 50mm diameter rear axle
  • Available in 1000mm, 1030mm and 1040mm lengths
  • Compatible with Tony Kart, Exprit, Kosmic, Redspeed and Energy chassis
  • 7 stiffness grades — more range than the genuine OTK lineup
  • Grades U, Q, N and H directly match genuine OTK equivalents
  • High-strength steel construction for race reliability

Why Choose the Senzo OTK Axle?

Seven stiffness grades means you've got a genuine answer for every condition — not just a choice between soft and hard. Whether you're chasing grip on a damp morning or trying to free up the rear on a high-rubber championship circuit, there's an exact grade for it. Most competitive drivers keep two or three stiffnesses in the van — a well-chosen axle swap is worth more than a full day of chassis tweaking.

KKC Kart Components — trusted karting parts built for performance, durability, and value on race day.