Yokomo YOKR12-37SH X Shock Hard Spring — Precision Hard-Rate Spring for RC Shocks  [YOKR12-37SH]

Compatibility and fitment notes for hard shock springs

This RC-scale shock spring is intended for use in general R/C spring sets and suspension tuning. The Yokomo YOKR12-37SH X Shock Hard Spring has a stronger rate than typical soft or medium coils and is designed to change suspension behaviour rather than act as a structural part.

Fitment is simple for those familiar with threaded shocks: remove the damper shaft assembly, transfer the coil onto the shock body, replace preload and retainers, and then confirm free travel and damping action. Only common shock service tools and a clean workspace are needed.

On-track role: a hard-rate spring increases ride firmness, reduces body roll and acceleration squat, and biases the chassis toward firmer compression control. These changes will influence both compression and rebound, so pair the spring with an appropriate oil and piston arrangement to tune overall damping.

Practical setup guidance: change only one variable at a time and test under repeatable conditions, keep a log of damper settings, and if the car feels unsettled over small irregularities after fitting a harder coil, reduce preload or try lighter oil before switching springs.