to fit this spur gear and clutch bell on my Buku clutch setup I needed to remove one carbon disc break from my setup. it's just too tall to fit under the smaller tooth 14 clutch bell. it was rubbing killing the free-moving clutch bell. So, I went into my stairs parts and added two metal brake pads to replace the thickness of one disc for proper space. works great at 49% breaking! Enjoy your RC!