Boom Racing BRX01 Chassis Kit

Stock is as the vehicle ships. Calculated is worked from the stock figures on this page rather than stored beside them, so the two cannot drift apart. Derived is worked out from gear tooth counts the maker publishes rather than printed as a ratio; the notes below say how. Not applicable means the vehicle does not come with it, like the motor on a roller or the tires on a race kit, or does not have one, like a KV rating on a brushed motor.

Gearing parts

Tooth counts are the ones in the specifications above. Pitch is given as metric module (Mod 1, Mod 0.8) or diametral pitch (32P, 48P). They are different standards and are not interchangeable, even where the numbers look close. Bore is the pinion’s hole, listed separately from the motor shaft. Linked part numbers go to the maker's or official distributor's page for that part.

How these numbers were settled

The kit's parts list includes a 32 pitch 12T steel pinion, which Boom Racing matches to a 27T or 35T 540/550 motor.

• The spur is the 28T 32 pitch composite gear Boom Racing names in the page's gear ratio section and sells as part BRLC7031.
• The stock tire is the 1.55in SP Road Tracker Gekko, printed as 3.46in x 0.94in (88mm x 24mm), on 1.55in steelie beadlock wheels.
• The spur is also named in the chassis features as a hard plastic 32 pitch 28T gear.
• The wheelbase is 313mm and the body is sold separately.
• Boom Racing's BRX01 gear ratio chart (on the BR8002 page) gives 20.30 in second gear and 45.11 in first for the 12T pinion on the 28T spur.
• The two-speed's high gear is used as the final drive, which puts the ratio after the spur at 20.30 x 12 / 28 = 8.70; use 45.11 in the calculator for first gear.
• It is a kit sold without motor, ESC or battery, so KV and cell count do not apply.

Documents

• ManualInstruction manual, BRX01 chassis kit (PDF) (opens in a new tab)Pinion PDF p. 8; spur PDF p. 44
• Exploded viewExploded view, BCF2 gearbox (in the BRX01 manual PDF) (opens in a new tab)PDF p. 44

Sources

• 1-10-4wd-radio-control-chas…boomracing.com (opens in a new tab)
• 28t-internal-spur-gear-32p-…boomracing.com (opens in a new tab)
• brx01-gear-ratio-table.pngboomracing.com (opens in a new tab)
• 1-10-4wd-radio-control-chas…boomracing.com (opens in a new tab)
• 32p-12t-3175mm-steel-pinion…boomracing.com (opens in a new tab)
• Manual (PDF)boomracing.com (opens in a new tab)

Every figure on this page traces to one of these. Where they disagreed, the note above says which was used and why.

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