Kyosho UM124 Tension Spring

The Kyosho UM124 Tension Spring is a genuine replacement spring for the transmission side of Kyosho's 1/10 scale off-road platforms. This small coil spring applies steady tension in the drivetrain assembly, keeping the gear train loaded correctly so the mesh stays consistent as the chassis flexes and the suspension works. Springs like this fatigue slowly and quietly over many run packs, and once the tension drops off you start to hear gear noise and feel inconsistency in the drivetrain that is easy to blame on other parts.

This is a direct factory replacement for the kit spring, requiring no modification to install. Kyosho lists it across the Ultima 1/10 range, covering the RT5, RB5, RB6, SC, and DB, and the same spring is called out in the Lazer ZX-5 parts list. At this price it makes sense to drop a fresh one in any time the gearbox is apart for a rebuild rather than reusing a spring that has been cycling for a season. Package includes one tension spring.