Setups
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Gearing
Stock gearing for the PR Racing SB401-R, with common pinions and their ratios.
| Pinion | Spur ÷ pinion | FDR |
|---|---|---|
| 16T | 5.06 | 13.16 |
| 17T | 4.76 | 12.39 |
| 18T | 4.50 | 11.70 |
| 19T | 4.26 | 11.08 |
| 20T | 4.05 | 10.53 |
| 21T | 3.86 | 10.03 |
| 22T | 3.68 | 9.57 |
| 23T | 3.52 | 9.16 |
| 24T | 3.38 | 8.78 |
| 25T | 3.24 | 8.42 |
| 26T | 3.12 | 8.10 |
| 27T | 3.00 | 7.80 |
| 28T | 2.89 | 7.52 |
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 PR Racing SB401-R, with the range racers in the class run.
Get a recommendation →Shop pinion gears at AMain →What pinion gear should I use on the PR Racing SB401-R?
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 SB401-R's stock 81T 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 SB401-R selected.
What is the internal ratio (transmission ratio) of the PR Racing SB401-R?
The SB401-R has an internal ratio of 2.6:1. Final drive ratio = spur ÷ pinion × 2.6. With the stock 81T spur, a 16T pinion gives an FDR of 13.16 and a 28T gives 7.52.
How many teeth is the stock spur gear on the PR Racing SB401-R?
81 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
- 450 cst
- Front
- Green 4.20lb #02530016 →
- Rear
- Yellow 2.70lb #02500086 →
- Front
- 2 x 1.8mm #17430096 →
- Rear
- 2 x 2.0mm #17430116 →
- Front
- 7,000 cst
- Rear
- 7,000 cst
What shock oil does the PR Racing SB401-R come with?
Out of the box the SB401-R runs 400 cst front, 450 cst rear, on 2 x 1.8mm (#17430096) front, 2 x 2.0mm (#17430116) 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 PR Racing SB401-R come with?
The kit springs are Green 4.20lb (#02530016) front, Yellow 2.70lb (#02500086) rear. Stiffer springs suit high grip and big jumps; softer springs add grip on slick or bumpy tracks.
What diff fluid does the PR Racing SB401-R come with?
The kit diff fluid is 7,000 cst front, 7,000 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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Setup App & Race Log
Your PR Racing SB401-R is in the RC Setup App
Save every setup change you make to your PR Racing SB401-R, get AI tuning answers for that exact car, and log your races — at the track or back in the pits.
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