What Is Axle Height?

Axle Height refers to the vertical position of the wheel axle relative to the suspension arm or hub carrier. In simple terms, it’s how high or low the axle sits within the suspension geometry—not the car’s Ride Height, but the axle’s position within the suspension itself.

On most modern RC vehicles (especially race platforms), Axle Height is adjusted using different hub mounting positions, inserts, or spacers that move the axle up or down.

A key thing to understand:
• Axle Height does NOT directly change Ride Height
• It changes how the suspension works around the Ride Height

Think of it as a geometry correction tool rather than a primary setup change.

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How Does Axle Height Affect Your Car?

Axle Height has a big impact on suspension geometry, especially roll center, droop and overall balance.

1. Roll Center Height
• Higher Axle Height = Higher Roll Center
• Lower Axle Height = Lower Roll Center

A higher Roll Center reduces chassis roll and makes the car feel more responsive. A lower Roll Center increases grip but adds body roll.

2. Droop and Suspension Travel
• Lower Axle Height = More Droop
• Higher Axle Height = Less Droop

More Droop helps the car stay planted on rough or low-grip tracks. Less Droop makes the car more precise and reactive.

3. Weight Transfer Behavior
Axle Height indirectly influences how weight transfers through the chassis:
• Lower Axle Height = slower, more forgiving weight transfer
• Higher Axle Height = quicker, more aggressive response

4. Maintaining Suspension Geometry
This is the most important function. Axle Height is commonly used to keep suspension arms level when adjusting Ride Height.

Example:
• Lower Ride Height arms angle upward
• Increase Axle Height = arms return to level

Level arms = predictable handling and consistent grip.

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How Do You Change Axle Height?

Adjustment depends on the vehicle, but most platforms use one of these methods:

1. Hub Carrier Mounting Holes
• Multiple vertical holes where the hinge pin sits
• Move the pin up/down to change Axle Height

2. Inserts (Common on Race Kits)
• Plastic or aluminum inserts in hubs
• Different offsets raise or lower the axle

3. Spacers/Shims
• Add spacers above or below the axle or hub
• Common on older or simpler designs

4. Caster Blocks / Uprights (Front End)
• Some platforms allow Axle Height tuning through front hub geometry changes

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When to Increase Or Decrease Axle Height

Increase Axle Height (Raise the Axle)
Use this when you want:
• Faster steering response
• Less body roll
• More precision on high-grip tracks
• Flatter suspension arm angle after lowering Ride Height

Best for:
• High-bite clay
• Carpet
• Smooth surfaces

Trade-off:
• Less forgiveness
• Reduced bump absorption

Decrease Axle Height (Lower the Axle)
Use this when you want:
• More overall grip
• Better handling on rough tracks
• Increased stability and forgiveness
• More droop and suspension compliance

Best for:
• Loose dirt
• Bumpy tracks
• Low traction conditions

Trade-off:
• Slower steering response
• More chassis roll

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What to Check After Changing Axle Height

Changing Axle Height affects multiple parts of your setup. If you skip these, the car can feel inconsistent.

1. Camber Link Position
Axle Height changes Roll Center so your Camber link must match. Typically:
• Raise axle = lower camber link
• Lower axle = raise camber link

2. Bump Steer (Front End)
• Adjust steering link height to maintain correct steering arc
• Prevents unpredictable steering input mid-corner

3. Ride Height
• Always re-check Ride Height after changes
• Axle Height is often used to support Ride Height adjustments

4. Droop Settings
• Axle Height directly affects Droop
• Re-measure and reset Droop screws if needed

5. Roll Center Balance (Front vs Rear)
Changing one end without the other can upset the overall balance. Always think in pairs:
• Front Axle Height vs rear Axle Height

6. Shock Setup
Changes in geometry may require:
• Different oil
• Different springs
• Shock position adjustments

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FAQ

Q: What’s the difference between Axle Height and Ride Height?
A: Ride Height is how high the chassis sits off the ground. Axle Height is where the axle sits within the suspension geometry. They work together but are not the same thing.

Q: Does Axle Height change ground clearance?
A: Not directly. Ride Height controls ground clearance. Axle Height changes how the suspension behaves around that Ride Height.

Q: Should I always keep my suspension arms level?
A: In most cases, yes. Level arms provide the most neutral and predictable handling. Axle Height is often used to achieve this when Ride Height changes.

Q: Is Axle Height a front or rear adjustment?
A: Both. Many race vehicles allow Axle Height tuning on the front hubs/uprights as well as the rear hubs. Each end affects different handling traits.

Q: What’s the easiest way to tune Axle Height?
A: Start with setting your Ride Height. Then adjust the Axle Height to level the arms. Finally, fine tune based on grip level.

Q: How big of a change should I make?
A: Small changes only. One step at a time (one hole or insert change). Axle Height is a fine-tuning adjustment, not a major setup change.

Back to the RC Suspension Tuning Guide.