Kyosho IFW405-138 SP Big Shock Piston 1.3x8 Hole

Special specification shock pistons for Kyosho's Big Bore dampers, drilled with eight holes of 1.3mm diameter, supplied two to a pack.

What separates an SP piston from a standard one is that the holes are drilled at an angle rather than straight through the disc. That produces a genuinely different damping character. At the low shaft speeds of normal driving the angled passages let oil through readily and the suspension stays supple over ripples and small chatter, but as shaft speed rises the angled path becomes progressively more restrictive and the damping firms up. Kyosho's own wording is that the damper operates suppley during normal driving and hardens on landing from a jump.

A straight-drilled piston cannot do this. It gives you one characteristic across the whole speed range, so you end up choosing between small-bump compliance and big-hit control. The SP piston lets you have more of both.

Eight holes at 1.3mm is the middle step of the SP range, one below the 1.4mm version. Fitment covers the Inferno MP9 and MP9e families, MP9 TKI through TKI4, Inferno NEO and NEO 3.0, Inferno GT3 and the ST-RR Evo. truggies.