Replacement 40Cr 21T Motor Pinion MG321T/0.5M for RC motors by GPM  [MG321T/0.5M]

40Cr Steel Motor Gear 21T ( Module:0.5mm, Motor Tooth Diameter:3.175mm) - GPM MG321T/0.5M
Price:
£5.87
Brand:
GPM
Model:
MG321T/0.5M
GTIN:
4894538411454
Condition:
Brand New
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RC motor pinion details

The GPM MG321T/0.5M motor gear is a compact 21-tooth pinion with a 0.5mm module, intended for accurate mesh in scale RC drivetrains. It is specified as 40Cr steel with a hardened black treatment to enhance wear resistance over standard untreated gears.

Dimensions are provided for fit checks: 21T, 0.5mm module, and a motor tooth diameter of 3.175mm with a round bore. The pinion secures to the motor shaft using two 3x3 set screws; confirm your motor shaft type and pinion spacing to achieve correct mesh before use.

Designed for simple replacement and light tuning work, this pinion keeps gear geometry predictable when matched to an appropriate spur. The hardened 40Cr construction helps resist early wear, and the dual set screw layout aids repeatable alignment on common motor shafts.

What should I check for compatibility?

Verify the pinion tooth count and module (21T, 0.5mm) and the motor tooth diameter (3.175mm). Also confirm that your motor shaft accepts set-screw style pinions and that there is enough shaft exposed for two 3x3 set screws.

Does the black finish change performance?

The hardened black surface is intended to reduce wear and provide longer life compared with untreated gears; it does not alter gear geometry but improves durability under normal conditions.

Any tips for securing the pinion?

Seat the pinion so it engages the spur across the face of the teeth, tighten the two set screws evenly, and manually rotate the drivetrain to confirm smooth, even contact before running the model.

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