Abstract: The present disclosure relates to a hydraulic actuator for a spring preload adjustment system for a shock absorber. The hydraulic actuator comprising a fluid chamber, a piston slidably arranged within the fluid chamber in a first direction for moving hydraulic fluid out of the fluid chamber to increase spring preload of a shock absorber connected to the hydraulic actuator. The piston is further slidably arranged within the fluid chamber in a second, opposite, direction for allowing hydraulic fluid to enter the fluid chamber to decrease spring preload of the shock absorber. The hydraulic actuator further comprises a drive assembly operatively engageable with the piston, the drive assembly comprising a drive unit, a lead screw operatively connected to the drive unit, and a gear element engaged with the lead screw and arrangeable to abut the piston.