Im currently running a 17.5t motor in my B5M. Gearing is 31/69. I started running outdoors this summer and the tracks are a lot bigger. Overall my torque is fine but top speed is really to slow to keep up with everyone else. Without switching the gearing too much and running too hot, a lot of people recommended going down to a 10.5T or a 8.5T.

Here is my question:

Right now im running a 17.5T motor with gears 31/69 and a final drive ratio of 5.8:1. If I went with a 10.5T with 24/81 gearing, which is recommended by the manual, the final drive would be 8.8:1. So overall with the 17.5T i'd actually have more top speed since it has a lower ratio, is this right?......I might be off on my thinking here?? ( i know i can change the gearing but im just curious based off the "recommended gearing")

Basically my car has enough torque but the tracks im running on are pretty wide open, soft/dry, backyard style so i need more top speed. I don't think i can go up too much more on my pinion gear without my car running too hot. I thought maybe getting a 10.5T motor would do the trick buuuut i'm not sure?

Of course going to 10.5t will get you more speed with less heat but if it's a 17.5 class you can't really do that

A 10.5t motor spins at a much higher rpm then a 17.5t does therefore you have to gear down in order to keep it cool. A brushless motor has tons of torque already that's not going to be an issue. Your manual is going to be on the conservative side, I'd start with a 25-26 tooth pinion. I'd bet tree 26 will be fine.

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okay so a 10.5T with lets say 24/81 gearing will have a higher top speed than a 17.5T with 31/69 gearing?

Right now im running an open class so it's more just for fun.

If it's an open class, just feed some timing to that 17.5... boost or turbo.. won't loose your grunt down low if done right, and can add tons to the top end..

I have a Durango dex210. 99% sure we have the same internal gear ratio. I did with the previous gen AE cars. I run a 10.5 turn with 30/81 gearing and I am not fast enough down the straight on the open 8th scale shared track I race on. I could get there with a smaller spur which I don't have yet. I am running 140 in 20 Celsius weather.