The pinion that can't let go. Arrma's Safe-D5 design puts a D-shaped bore on this steel 26-tooth pinion to match the flat on Arrma/Spektrum 5mm motor shafts — so if the set screw ever vibrates loose (and on a hard-driven basher, set screws try), the D-profile keeps turning the gear: no lost drive, and critically, no lost brakes. A conventional round-bore pinion with a backed-out grub screw freewheels; this one keeps you in control. Machined from durable steel with a precision wide-tooth profile, supplied with a fresh M4 set screw and a 3.2mm E-clip for positive shaft retention.

Fitment — Read Before Buying

Suits 0.8Mod (32P-compatible pitch) Arrma 3S BLX platforms — Big Rock, Typhon, Senton, Granite and family — on their standard 5mm Spektrum/Arrma motor shafts. The boundary matters: the D-shaped bore fits D-profile shafts only — it will not slide onto round 5mm shafts, so aftermarket motors (Castle and similar) with round shafts need a conventional round-bore pinion instead. Changing tooth count changes gearing: more teeth trade acceleration for top speed and run warmer — check your model's manual for its recommended pinion range before stepping up from stock.

Specifications

Brand: Arrma
SKU: ARA311009
Product: Safe-D5 pinion gear
Teeth / Pitch: 26T, 0.8Mod
Bore: 5mm D-profile — Arrma/Spektrum D-shafts only
Material: Steel, wide tooth profile
Included: Set screw M4×4mm, E-clip 3.2mm
Suits: Arrma 3S BLX family (Big Rock, Typhon, Senton, Granite)
Not For: Round 5mm motor shafts (aftermarket motors)