G-6/G-10 Gears 10303: When a Spare Pair Helps
A gear is a useful spare only when it replaces the gear train you actually own. Tamiya item 10303 contains one light-green G-6 gear with 30 teeth and one blue G-10 compound gear marked 24T/18T. Tamiya pairs them for a 5:1 ratio. Keep that exact number on your parts list: a bag labelled simply ‘Mini 4WD gears’ can contain a different ratio or a gear for another motor layout.
Read the pair before ordering
Check the chassis and kit instructions, then compare the colour and tooth markings on the installed gears. Tamiya lists item 10303 for several older single-shaft chassis, including Super-II, Super X, Super XX, VS and AR; its product page does not list MA, MS, VZ or FM-A. A shared Mini 4WD name is not a fit guarantee. If the original gearing has been changed, identify the installed pair rather than assuming the box-stock ratio remains.
A spare is for a specific fault
A chipped tooth, rounded hub, slipping gear or damaged mating gear gives a practical reason to keep a matched replacement ready. Switch off the car and remove batteries before opening the gearbox. Look for loose fragments and a gear cover that will not seat flat. Replacing the visible broken gear without finding the cause can damage the new pair. The official gear-ratio matching table helps confirm the companion components.
Rebuild and check
Use the kit drawing for gear order and orientation. Turn both axles by hand before fitting batteries: they should move without a hard spot or scraping cover. Make one change, then run the car briefly and inspect again. Item 10303 restores a documented 5:1 arrangement; it is not a promise of a faster lap. Track shape, motor and tire diameter still determine whether a ratio suits your build.
Check current availability and the exact variant on the product listing before ordering.
Related reading
Frequently asked questions
Does 10303 fit an MA chassis?
MA is not on Tamiya's compatibility list for item 10303; check an MA-specific gear set instead.
Should I buy a spare if the car runs normally?
A spare makes sense when your installed gear pair matches 10303 and you want a same-ratio replacement at an event.
Sources checked 26 September 2026: https://www.tamiya.com/english/products/10303/index.html, https://www.tamiya.com/cms/english/mini4wd/pdf/gr_table.pdf. Recheck product availability before ordering.