Yokomo YOKBMS12100 — BMax4 Rear Shock Spring 12100 (Orange/Soft)  [YOKBMS12100]

Rear spring for BMax4 rear shocks

This is an RC-scale rear suspension spring specified for BMax4 rear shock assemblies. The orange soft coil provides a lower spring rate suited to setups that require increased rear compliance, such as low-traction surfaces or fine-tuning weight transfer on 1/10 electric touring cars.

Compatibility and fitment are focused on BMax4 rear shock housings and standard spring retainers used on that platform. Installation follows standard shock service procedures: remove the shock from the chassis, compress and remove the spring cap, swap the spring, then reinstall and check preload and ride height. Use common RC tools like hex drivers and shock pliers for safe handling.

Tuning notes: a softer rear spring reduces sprung stiffness at the rear axle, which can increase mechanical grip but also raise body roll and squat under acceleration. Balance spring choice with shock oil viscosity and piston selection to maintain desired damping and rebound response. Make incremental changes and test on-track to evaluate handling differences.