I recently upgraded my 1/18 truck to a lipo and brushless setup. And it ran great, for about 5 seconds. The new pinion gear shredded the stock spur gear.

I'm pretty sure it was because the teeth on the pinion are smaller than the spur.

So I'm pretty confused how to pick a new spur. Do I have to get the pitch's the same? The new pinion doesn't have a pitch measurement, but is .4 module. is there a way to convert? Also, how do you know if the spur will fit your setup? All the spur gears i'm finding have different sized holes in the middle. Does each one come with it's own fittings?