Kyosho IS104 103mm Lightweight Center Universal Swing Shaft

This is Kyosho's lightweight centre universal swing shaft for the Inferno ST truggy range, measuring 103mm.

A universal joint shaft differs from a plain dogbone in that it maintains constant velocity through its operating angle rather than speeding up and slowing down twice per revolution. In the centre of a four-wheel-drive chassis, where the shaft runs at full drivetrain speed and carries the whole torque load, that difference shows up as smoother power delivery and noticeably less vibration through the chassis.

The lightweight designation matters because this is rotating mass. Kyosho describes it as a light-weight type using new materials, and weight removed from a component spinning at drivetrain speed pays back more than the same weight taken off the chassis, since the engine has to accelerate it every time you get on the throttle.

The shaft is also the wearing element of the assembly, taking constant articulation under full load. Once play develops you get a knock on throttle transitions and accelerating wear on the diff outdrives either side.

One piece supplied. Kyosho lists IFW161 as the substitution part.