Well, I'm using 27T pinion and there is about 1mm gap between this and motor gear and I can' grind any more rear diff mount as it will grind bearings...
So i'm thinking of changing rear diff mount. Where can I get the one that can fit 540 motor? I saw one on AktionRC
I have some bad news for you though, the motor mount won't help you. the can size of the 540 means that you'll still have to grind down the bearing casing just as much.