GFC|TB Kart Stub Axle (Senior/Junior)

Cadet Stub Axles: 

The RR5 or TB Monster has one stub axle choice 

Senior/Junior Stub Axles: 

The 0.5° difference between a 10.5° and 11° stub axle doesn't sound like much, but in karting it can noticeably change how the front end behaves because the stub axle affects the kingpin inclination (KPI) and scrub radius. Think of it as changing the front suspension's personality rather than its outright grip.

Here's what you can generally expect:

10.5° Stub Axles

These are often preferred when:

• Track grip is high.
• The kart is hopping or jacking too much.
• The driver likes a smoother steering feel.
• You're trying to calm an aggressive front end.

The kart tends to:

• Roll into the corner more naturally.
• Keep the rear planted.
• Be easier to drive over a race distance.

11° Stub Axles

These are commonly used when:

• Grip is low.
• You need more front-end bite.
• The kart struggles to rotate.
• Hairpins and slow corners dominate the circuit.

The kart tends to:

• Lift the inside rear tyre more aggressively.
• Rotate quicker at corner entry.
• Feel more responsive but also more nervous.

Why only half a degree matters

Because the kingpin angle changes the leverage of the steering geometry, a small change can:

• Increase or decrease chassis jacking.
• Alter tyre contact patch through steering lock.
• Change steering self-centering.
• Affect how much the chassis unloads the inside rear.

On a well-balanced chassis, many drivers can feel the difference.

GFC/TB Kart Example

Since you've been working extensively with the GFC chassis, the choice would typically be:

• 10.5°: Rubbered-in tracks, warm conditions, MG Reds or similar high-grip tyres, or when the kart is hopping.
• 11°: Green tracks, cooler conditions, rain (sometimes), or whenever you need more rotation and front-end response.

Is it worth changing?

A good rule of thumb is:

• Kart won't turn? Try 11°.
• Kart turns too much or hops? Try 10.5°.

Compared with changing caster pills, the stub axle produces a more fundamental change to the front geometry. Many experienced tuners use the stub axle to establish the kart's baseline character, then fine-tune with caster, front width, ride height, and torsion bars.