Ask Miles, our Setup AI that’s been trained on the SB401R-T.
Setups
Gearing
Stock gearing for the PR Racing SB401R-T, with common pinions and their ratios.
| Pinion | Spur ÷ pinion | FDR |
|---|---|---|
| 14T | 5.79 | 22.56 |
| 15T | 5.40 | 21.06 |
| 16T | 5.06 | 19.74 |
| 17T | 4.76 | 18.58 |
| 18T | 4.50 | 17.55 |
| 19T | 4.26 | 16.63 |
| 20T | 4.05 | 15.79 |
| 21T | 3.86 | 15.04 |
| 22T | 3.68 | 14.36 |
| 23T | 3.52 | 13.73 |
| 24T | 3.38 | 13.16 |
| 25T | 3.24 | 12.64 |
| 26T | 3.12 | 12.15 |
| 27T | 3.00 | 11.70 |
Shaded rows are the pinions most 1/10 4WD truck 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 SB401R-T, 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 SB401R-T?
It depends on your motor and the track. Racers in the 1/10 4WD truck class run a 16–25 tooth pinion in most setups, usually on a 81T spur for a final drive ratio near 10.93. Hotter motors (lower turns, higher Kv) take a smaller pinion; tight tracks gear down, open tracks gear up. For a starting pinion matched to your motor, use the So Dialed Pinion Recommender with the SB401R-T selected.
What is the internal ratio (transmission ratio) of the PR Racing SB401R-T?
The SB401R-T has an internal ratio of 3.9:1. Final drive ratio = spur ÷ pinion × 3.9. With the stock 81T spur, a 14T pinion gives an FDR of 22.56 and a 27T gives 11.70.
How many teeth is the stock spur gear on the PR Racing SB401R-T?
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
- 450 cst
- Rear
- 450 cst
- Front
- Blue/red 4.76lb #02530036 →
- Rear
- Blue/red 3.60lb #02530076 →
- Front
- 2 x 1.8mm #17430096 →
- Rear
- 2 x 1.8mm #17430096 →
- Front
- 10,000 cst
- Center
- 30,000 cst
- Rear
- 7,000 cst
What shock oil does the PR Racing SB401R-T come with?
Out of the box the SB401R-T runs 450 cst front, 450 cst rear, on 2 x 1.8mm (#17430096) front, 2 x 1.8mm (#17430096) 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 SB401R-T come with?
The kit springs are Blue/red 4.76lb (#02530036) front, Blue/red 3.60lb (#02530076) 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 SB401R-T come with?
The kit diff fluid is 10,000 cst front, 30,000 cst center, 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 SB401R-T is in the RC Setup App
Save every setup change you make to your PR Racing SB401R-T, get AI tuning answers for that exact car, and log your races — at the track or back in the pits.
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