Originally Posted by Laguna Bozo

FX35rc, +1, had the same experience. Tried to tighten the M05 diff to make it as tight as the TA03 diff in my M03, and the screw broke after a few batteries. But I didn't go to the TA03 diff, I wanted to keep it all M05, and just learned how to build the M05 diff better. Yes, you need ceramic balls, buff the rings, good thrust bearing and all that (can you tell I hang out with Grandpa?), just don't tighten the poop out of it. Tight, then back off a little, find that smooth spot, still resistant but smooth. On our rather open outdoor asphalt track, this is the way to keep your speed up and get great steering. Now it's just up to you to hold it on line!
If all the stars line up, I think I can lap my M03 a tiny bit faster than the M05. If conditions aren't perfect, the M05 is easier to drive and more consistent. It's got something to do with weight balance...