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Stock gearing for the Yokomo YZ-4 SF, with common pinions and their ratios.
| Pinion | Spur ÷ pinion | FDR |
|---|---|---|
| 16T | 5.25 | 13.13 |
| 17T | 4.94 | 12.35 |
| 18T | 4.67 | 11.67 |
| 19T | 4.42 | 11.05 |
| 20T | 4.20 | 10.50 |
| 21T | 4.00 | 10.00 |
| 22T | 3.82 | 9.55 |
| 23T | 3.65 | 9.13 |
| 24T | 3.50 | 8.75 |
| 25T | 3.36 | 8.40 |
| 26T | 3.23 | 8.08 |
| 27T | 3.11 | 7.78 |
| 28T | 3.00 | 7.50 |
Shaded rows are the pinions most 1/10 4WD buggy setups run on the stock spur.
What pinion should I run?
Tell us your motor and track and get a starting pinion for the Yokomo YZ-4 SF, with the range racers in the class run.
Get a recommendation →Shop pinion gears at AMain →It depends on your motor and the track. In the 1/10 4WD buggy class, racers gear by final drive ratio: 6T and below near 10.66, 7.5–8.5T near 10.00, 13.5T near 7.95. On the YZ-4 SF's stock 84T spur that is about 20T for 6T and below, 21T for 7.5–8.5T, 26T for 13.5T. Tight tracks gear down, open tracks gear up. For a starting pinion matched to your motor, use the So Dialed Pinion Recommender with the YZ-4 SF selected.
The YZ-4 SF has an internal ratio of 2.5:1. Final drive ratio = spur ÷ pinion × 2.5. With the stock 84T spur, a 16T pinion gives an FDR of 13.13 and a 28T gives 7.50.
84 teeth. Changing the spur moves every pinion's ratio at once; most racers leave the spur and tune with the pinion.
Kit shock setup. Part numbers link to AMain.
Out of the box the YZ-4 SF runs 500 cst front, 350 cst rear (Yokomo oil), on 2 x 1.6mm, 2.0mm thick black (#S162) front, 2 x 1.7mm white (#S172) 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.
The kit springs are Orange (#A750) - lightest front, Green (#YOKYS-A1200) - lightest rear. Stiffer springs suit high grip and big jumps; softer springs add grip on slick or bumpy tracks.
The kit diff fluid is 5,000 cst front, 5,000 cst rear. Thicker front adds steering on power; thicker center sends more drive rearward; thicker rear stabilizes the car under throttle.
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Your Yokomo YZ-4 SF is in the RC Setup App
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