Kyosho UMW726 Aluminum Gear Diff Case Cap RB6 / RT6 / SC6

Kyosho UMW726 is an aluminium cap for the gear differential case, replacing the plastic cap supplied with the UMW604 gear diff set.

Two things change when you fit it. The alloy cap clamps down more evenly on the diff case, so the seal holds better and the diff is less likely to weep fluid out under load — which is what quietly changes a diff setting mid-run. Aluminium also pulls heat out of the diff rather than trapping it, and a cooler diff keeps its fluid at the viscosity you filled it with.

Kyosho lists this as an option part for the Ultima RB6, RT6 and SC6, and it is specific to the UMW604 gear diff. Note that Kyosho's own catalogue heading calls it a "Cup" — it is the diff case cap.

• Genuine Kyosho part number UMW726
• Aluminium gear diff case cap
• Fits the UMW604 gear diff set
• Option part for Ultima RB6, RT6 and SC6