Axle height is the distance between the axle and the lower suspension arm pivot.
Some cars allow changes to the axle height, usually with multiple holes at the bottom of the hub or caster block for the pin that connects the hub to the suspension arm, or by using inserts in the bottom of the hub that have various options for the height of the hole.
Axle height adjustments allow you to keep the suspension arms level when changing ride height. For example, if you lower the ride height (chassis), you may want to increase the axle height so the lower suspension arms remain level rather than angling up towards the outside.
The absolute measurement of the axle height is not very important - it is the relative changes in axle height that will help you tune your car.
Lower axle height
- Lower roll center
- More droop
- Generally suited for low-grip tracks
Higher axle height
- Higher roll center
- Less droop
- Generally suited for high-grip tracks
To maintain suspension geometry, you may want to:
- Front: lower the steering arm ball stud (bump steer) as axle height increases and vice versa
- Rear: lower the outer camber link ball stud as axle height increases and vice versa
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