VehiclesArrma Big Rock 6S BLX
Arrma Big Rock 6S BLX
1/7 scale · monster truck · ARA7612
- Top speed
- 52mphstock gearing
- Speed set
- 64mphincluded in the box
- Final drive
- 16.54:1
- Tire
- 162mm
Specifications
Last modified
| Spec | Value | Basis |
|---|---|---|
| Drivetrain | ||
| Pinion | 13TStock | Stock |
| Spur | 50TStock | Stock |
| Transmission & axle | 4.30:1Stock | Stock |
| Spur ÷ pinion | 3.846:1Calculated | Calculated |
| Final drive | 16.54:1Stock | Stock |
| Speed gearing, in the box | 16T / 50Tpinion / spurStock | Stock |
| Final drive, speed gearing | 13.44:1Stock | Stock |
| Wheels & tires | ||
| Tire diameter | 162mmEstimated | Estimated |
| Rollout | 30.8mm per motor turnCalculated | Calculated |
| Power | ||
| Motor | 2050KVStock | Stock |
| Battery | Up to 6SLiPoStock | Stock |
| Performance | ||
| Theoretical top speed, stock gearing | 52.2mph on 6SCalculated | Calculated |
| Theoretical top speed, speed gearing | 64.3mph on 6SCalculated | Calculated |
| Motor speed | 45,510rpm, no loadCalculated | Calculated |
| Advertised top speed | 65mphMaker's claim | Maker's claim |
| Vehicle | ||
| Part number | ARA7612 | |
| Scale | 1/7 | |
| Class | Monster truck | |
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. Speed gearing is the taller set that ships in the box but is not fitted; swapping it in is the owner's job, and the car runs hotter on it. The maker advertises 65 mph, which is their own claim on their own conditions.
How these numbers were settled
The 1/7 Big Rock 6S crew cab is a separate, larger vehicle from the 1/10 Big Rock 3S BLX V3.
- Horizon publishes the Spektrum Firma 4074 2050Kv motor, the Firma 150A Smart V2 ESC, a 6S ceiling and a 65+ mph claim.
- Horizon's standard-parts list for ARA7612 names a 50T limited-slip centre diff and spiral diffs with a 10T input against a 43T ring (4.3).
- Stock pinion is 13T per AMain's spec list, giving 50/13 x 4.3 = 16.54.
- The manual's kit overview (p.6) lists a supplied 16T 'Speed' pinion, and the 65+ mph claim assumes it: 50/16 x 4.3 = 13.44.
- The tire diameter is the weakest figure and is why this sheet is graded community: 162mm for the stock dBoots Ragnarok comes from a forum member's measurement, not from Arrma.
Sources
- ARA7612horizonhobby.com (opens in a new tab)
- arrma-big-rock-6s-center-di…jennysrc.com (opens in a new tab)
- arrma-big-rock-6s-tires-whe…jennysrc.com (opens in a new tab)
- calculating-motor-pinion-si…arrmaforum.com (opens in a new tab)
- p1532265amainhobbies.com (opens in a new tab)
- searchhorizonhobby.com (opens in a new tab)
- big-rock-6s-tire-diameter.6…arrmaforum.com (opens in a new tab)
- Manual (PDF)horizonhobby.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.