Kyosho TF120 Ball Diff Screw Set

Kyosho TF120 is the genuine ball differential screw set for Kyosho's 1/10 platforms. The diff screw is the single most important adjustment in a ball differential: threading it in or out changes the clamping pressure on the diff plates and balls, which sets how much the diff slips under power. A worn or stretched screw makes that adjustment vague and lets the setting drift during a run, so replacing it is one of the first things to do when a diff stops holding.

Originally released for the TF-5 Stallion touring car, this screw set is also called out in Kyosho's off-road parts lists, covering the Ultima RT5, RT6, RB5, RB6, and SC and the Ultima SB Dirt Master. It installs as a direct replacement for the kit hardware with no modification. Fitting a fresh screw alongside new diff balls, plates, and thrust bearing is the standard full-rebuild practice that restores crisp, predictable diff action.