XO-1 Telemetry Math Gone Crazy

I discovered this a while ago. I didn't really say anything, because at the time I didn't think anyone would be interested. Now though, with the new crop of XO-1 owners wanting to get into Traxxas telemetry, I wanted to point out this little telemetry boo-boo.

It all started when I wanted to change my gears, but not my gear ratio. The reason? I wanted bigger gears that would give be a bigger space between my motor and my driveshaft. Why? Because, little rocks was tearing up my driveshaft, and I wanted to see if a bigger motor/driveshaft gap would help. I went to the owners manual, and here's what I saw.

[img]https://i.imgur.com/8zHt9wY.jpg[/img]

If you only use the (above) formula and gearing chart, you would never see the problem. The problem came when I went to the (below) Traxxas telemetry "GARAGE" and the "MODEL SETUP."

[img]https://i.imgur.com/6LVGesR.jpg[/img]

What is the correct gear ratio for a 14T pinion gear, and a 46T spur gear? Is it 2.846 or 9.35? I plugged in both numbers (even though the 2.846 is a telemetry default) to see what would happen.

The telemetry default gear ratio of 2.846 was definitely a good number. The owners manual's final gear ratio of 9.36 for gears 14/46 made my speedometer go crazy.

So, here's what I did to correct this.

[img]https://i.imgur.com/F6scx3J.jpg[/img]

We know that 46/14 is a good number. The number 9.36 proved to be a bad number when used with Traxxas' telemetry. And, 2.83 proved to be a bad number in our owner manual's formula, but is a good number when used as or final gear ratio default setup.

So, what needed to be done was to take our Traxxas formula, use the 46/14, make 2.85 unknown (or X), and use our proven 2.842 telemetry number as our formula's solution.

If we do that, our new corrected formula for our owner's manual is: Spur/Pinion (times) .865 = Final Gear Ratio

Now, when we use our new corrected formula for our first step: 46/14 = 3.2857

And, for our second and final step: 3.2857 x .865 = [B]2.842[/B] (the number used as our default final gear entry, in our Traxxas telemetry setup)

In conclusion, I have the spacing I wanted, and am able to keep my original OEM gear ratio. I had my choice of using either 54/17 = GR 27476 or 54/16 = GR 2.919. I went with the gear ratio of 15/17. When I plugged in all the numbers into my Traxxas telemetry program, everything worked very well, my top speed was 58mph, and no more shredding of my driveshaft from rocks.