Setups
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Gearing
Stock gearing for the Tamiya TRF421, with common pinions and their ratios.
| Pinion | Spur ÷ pinion | FDR |
|---|---|---|
| 20T | 5.80 | 10.73 |
| 21T | 5.52 | 10.22 |
| 22T | 5.27 | 9.75 |
| 23T | 5.04 | 9.33 |
| 24T | 4.83 | 8.94 |
| 25T | 4.64 | 8.58 |
| 26T | 4.46 | 8.25 |
| 27T | 4.30 | 7.95 |
| 28T | 4.14 | 7.66 |
| 29T | 4.00 | 7.40 |
| 30T | 3.87 | 7.15 |
| 31T | 3.74 | 6.92 |
| 32T | 3.63 | 6.71 |
| 33T | 3.52 | 6.50 |
| 34T | 3.41 | 6.31 |
| 35T | 3.31 | 6.13 |
| 36T | 3.22 | 5.96 |
| 37T | 3.14 | 5.80 |
| 38T | 3.05 | 5.65 |
| 39T | 2.97 | 5.50 |
| 40T | 2.90 | 5.37 |
| 41T | 2.83 | 5.23 |
| 42T | 2.76 | 5.11 |
| 43T | 2.70 | 4.99 |
| 44T | 2.64 | 4.88 |
| 45T | 2.58 | 4.77 |
| 46T | 2.52 | 4.67 |
| 47T | 2.47 | 4.57 |
| 48T | 2.42 | 4.47 |
| 49T | 2.37 | 4.38 |
| 50T | 2.32 | 4.29 |
| 51T | 2.27 | 4.21 |
| 52T | 2.23 | 4.13 |
Shaded rows are the pinions most 1/10 4WD touring/gt setups run on the stock spur.
What pinion should I run?
Tell us your motor and track and get a starting pinion for the Tamiya TRF421, with the range racers in the class run.
Get a recommendation →Shop pinion gears at AMain →What pinion gear should I use on the Tamiya TRF421?
It depends on your motor and the track. In the 1/10 4WD touring/gt class, racers gear by final drive ratio: 6T and below near 7.34, 13.5T near 4.51, 17.5T near 4.51, 21.5T and up near 3.65. On the TRF421's stock 116T spur that is about 29T for 6T and below, 48T for 13.5T, 48T for 17.5T, 59T for 21.5T and up. Tight tracks gear down, open tracks gear up. For a starting pinion matched to your motor, use the So Dialed Pinion Recommender with the TRF421 selected.
What is the internal ratio (transmission ratio) of the Tamiya TRF421?
The TRF421 has an internal ratio of 1.85:1. Final drive ratio = spur ÷ pinion × 1.85. With the stock 116T spur, a 20T pinion gives an FDR of 10.73 and a 52T gives 4.13.
How many teeth is the stock spur gear on the Tamiya TRF421?
116 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
- 400 cst
- Rear
- 400 cst
- Front
- 4-hole
- Rear
- 4-hole
What shock oil does the Tamiya TRF421 come with?
Out of the box the TRF421 runs 400 cst front, 400 cst rear, on 4-hole front, 4-hole 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 Tamiya TRF421 come with?
The kit springs are Dark Grey-Green Short (#42306) front, Dark Grey-Green Short (#42306) rear. Stiffer springs suit high grip and big jumps; softer springs add grip on slick or bumpy tracks.
Setup Help
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