Setups
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Gearing
Stock gearing for the Tamiya TRF420X, 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 TRF420X, 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 TRF420X?
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 TRF420X'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 TRF420X selected.
What is the internal ratio (transmission ratio) of the Tamiya TRF420X?
The TRF420X 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 TRF420X?
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 (Manual). Part numbers link to AMain.
- Front
- 400 cst
- Rear
- 400 cst
- Rear
- 3,000 cst
What shock oil does the Tamiya TRF420X come with?
Out of the box the TRF420X runs 400 cst front, 400 cst rear, on 4-hole (#54728) front, 4-hole (#54728) 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 TRF420X 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.
What diff fluid does the Tamiya TRF420X come with?
The kit diff fluid is 3,000 cst rear. Thicker front adds steering on power; thicker center sends more drive rearward; thicker rear stabilizes the car under throttle.
Setup Help
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