ring and pinion stripping

[RCParts411]

I had the exact same issue and symptoms with my Kyosho St-RR at the track last Sunday. I did however have to replace the gears. Even the second set of gears started to grind a little. When I took it apart I noticed 1 of my shims was not seated correctly.

From what I was told shimming is key. My front diff has 2 shims on each side. I moved 1 shim over to create a tighter mesh with the ring/pinion. I've only tested on the street after adjusting the shims but the sound disappears even under the heaviest of braking.

You'll probably just want to go ahead and replace you ring & pinion. Once its stripped out a little theres nothing you can do.