Originally Posted by robk
I have done this with no problem. AreCee I was racing you with a 64 pinion and a 0.4 spur!
I've done the same thing, like I said it can be noisier (unless you set the mesh just perfect) and since the teeth have different profiles the softer plastic spur gear will wear out faster than if you use 64p gears.
I may still have some of those real soft aluminum pinions Kyosho included with their kits. One of those pinions has teeth pointing backwards.
Bottom line is that it can be used but your experience may differ from that of others.