Setups
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Gearing
Stock gearing for the ARC R8.4ES, with common pinions and their ratios.
| Pinion | Spur ÷ pinion | FDR |
|---|---|---|
| 11T | 5.18 | 12.44 |
| 12T | 4.75 | 11.40 |
| 13T | 4.38 | 10.52 |
| 14T | 4.07 | 9.77 |
| 15T | 3.80 | 9.12 |
| 16T | 3.56 | 8.55 |
| 17T | 3.35 | 8.05 |
| 18T | 3.17 | 7.60 |
| 19T | 3.00 | 7.20 |
| 20T | 2.85 | 6.84 |
| 21T | 2.71 | 6.51 |
| 22T | 2.59 | 6.22 |
What pinion should I run?
Tell us your motor and track and get a starting pinion for the ARC R8.4ES, with the range racers in the class run.
Get a recommendation →Shop pinion gears at AMain →What pinion gear should I use on the ARC R8.4ES?
It depends on your motor and the track. A hotter motor (lower turns, higher KV) takes a smaller pinion; a tight track wants a lower gear than an open one. Start near the middle of the pinions the R8.4ES shipped with, run a few minutes, and check motor temperature before going up a tooth. The So Dialed Pinion Recommender gives a starting pinion for your motor where we have class data.
What is the internal ratio (transmission ratio) of the ARC R8.4ES?
The R8.4ES has an internal ratio of 2.4:1. Final drive ratio = spur ÷ pinion × 2.4. With the stock 57T spur, a 11T pinion gives an FDR of 12.44 and a 22T gives 6.22.
How many teeth is the stock spur gear on the ARC R8.4ES?
57 teeth. Changing the spur moves every pinion's ratio at once; most racers leave the spur and tune with the pinion.
Kit setup
Kit shock setup. Part numbers link to AMain.
- Front
- 800 cst
- Rear
- 800 cst
- Front
- 9.0C White #R847032 →
- Rear
- 7.4C White #R847040 →
- Front
- 2 x 1.0mm
- Rear
- 2 x 1.0mm
What shock oil does the ARC R8.4ES come with?
Out of the box the R8.4ES runs 800 cst front, 800 cst rear, on 2 x 1.0mm front, 2 x 1.0mm rear pistons. That is the kit setup; you will need to adjust it for your track conditions. The RC Setup App can help dial it in.
What springs does the ARC R8.4ES come with?
The kit springs are 9.0C White (#R847032) front, 7.4C White (#R847040) rear. Stiffer springs suit high grip and big jumps; softer springs add grip on slick or bumpy tracks.
Setup Help
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