Kyosho UM112B 4.8mm Ball End Cap

This is the 4.8mm ball end cap used on Kyosho's Ultima and Lazer platforms, the molded cup that snaps over a 4.8mm pivot ball to form a suspension or steering linkage joint.

Ball ends are wear items and they matter more than their price suggests. A fresh cap grips the ball with a firm, consistent snap so the linkage pivots smoothly without any free play. As the cup wears, the joint develops slop, and that slop shows up at the wheel as vague steering, inconsistent camber under load, and a car that will not hold the same setup from one run to the next. A badly worn cap can also pop off the ball mid-corner, which usually ends the heat.

Replacing them is quick and requires no disassembly beyond popping the old cap free. This is the genuine Kyosho part, so it snaps onto the standard 4.8mm balls with the correct retention rather than being loose or over-tight.

Dealers list fitment as the Ultima RT5, RB5, SC and DB, the Lazer ZX-5, and the V-One RRR. This part supersedes the earlier UM112.