Bump Stop and Rebound Stop
Bump stops and rebound stops limit suspension movement near the compression and extension ends of travel.
Bump stop
A bump stop is engaged near full compression. It prevents damaging contact or overtravel and often acts as a progressively increasing secondary spring before the hard mechanical limit. Its material, shape, clearance, and engagement point affect wheel rate and body control when heavily loaded or during large road inputs.
Rebound stop
A rebound stop limits extension. It may be integrated into the damper, formed by an internal spring, strap, top-out bumper, or another mechanical feature. It protects joints and components from excessive extension and can influence how the wheel follows a crest or drop.
Not unused emergency parts
Stops may be part of normal suspension tuning rather than components touched only in an extreme event. Repeated or early contact can also indicate heavy loading, insufficient ride height, weak springs, unsuitable parts, or a fault. The wheel, spring, and damper reach their limits through different motion ratios.
For suspension travel and component motion, see Suspension Kinematics and Vehicle Dynamics. Spring and damper behavior are explained in Suspension Springs and Suspension Dampers.