Traxxas X-Maxx Ultimate

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. The top speed is kinematic: an ideal no-load RPM with no slip and no loss under load, so a real car is slower. The maker advertises 40 mph, which is their own claim on their own conditions.

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 (5 mm on the stock motor). Linked part numbers go to the maker's or official distributor's page for that part.

How these numbers were settled

The product page prints 'Gear Ratio (Internal): 8.11 (stock, out-of-box)', which is the ratio after the spur, and the owner's manual formula is spur / pinion x 8.11.

• Traxxas's X-Series gearing chart marks an 18-tooth pinion on the 54-tooth spur as the included stock gearing and marks no speed gearing as included; the product page says the optional gearing for 50+ mph is sold separately.
• The parts list sets the machined 18-T pinion (6491R) and the machined 54-tooth spur (6444) in regular type, with the standard 51T/20T transmission gears rather than the overdrive set, and the 6491R and 6444 part pages list this truck as a stock fitment.
• The total is 54/18 x 8.11 = 24.33.
• The tire is the 8.4 in belted Sledgehammer, from the tire part page.
• The manual quotes 40+ mph on two 4S packs with stock gearing, about 90 percent of the no-load speed at full charge.

Documents

• ManualOwner's manual, model 77097-4 R05 (Traxxas PDF) (opens in a new tab)Gear ratio formula p. 28
• Gearing chartX-Series gearing chart (opens in a new tab)X-Maxx Ultimate 77097-4 table
• Parts listParts list, 77097-4 (Traxxas PDF) (opens in a new tab)Spur and pinion gears
• Exploded viewExploded view, rear assembly (Traxxas JPG) (opens in a new tab)Spur 6444, transmission gears 7784X and 7785X

Sources

• x-maxx-ultimate-77097-4traxxas.com (opens in a new tab)
• Manual (PDF)traxxas.com (opens in a new tab)
• Manual (PDF)traxxas.com (opens in a new tab)
• x-series-gearingtraxxas.com (opens in a new tab)
• 77097-4_X-Maxx%20Ultimate_T…traxxas.com (opens in a new tab)
• 7871-black-x-maxx-wheels-be…traxxas.com (opens in a new tab)
• 7870-x-series-belted-sledge…traxxas.com (opens in a new tab)
• 6491r-18-tooth-machined-pin…traxxas.com (opens in a new tab)
• 6444-54-tooth-wide-face-mac…traxxas.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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