OK, I will start by saying the answer is probably "your diff is too loose" but...
For a while now my Pede has shown some bizarre spin out problems. Started in winter while ice driving (no studs or chains), 13T speed gem, 6 cell, M2K's, steel outdrives, aluminum idler. You get on the throttle REALLY easy and the truck would start going fine. Get to about half throttle and it would donut. OK, that's ice, what else would I expect? Then, at the track- frozen dirt track, same thing with the same motor. OK, what else would I expect when driving on what feels like ball bearings?
I rebuilt the diff recently, using the standard silicone grease I have been using for years. Not the stiffest, but certainly stiffer than stock Traxxas grease. This weekend, now with a Chameleon 2 (7 cells though), I was seeing the same thing but now it was on high traction grass!?! Get going and when you are almost up to speed, the truck would just spin around. I haven't done that much 7 cell driving but over the few years I have had a Pede,, I have NEVER seen this happen on grass.
So, any ideas other than get a real thick axle grease or something for that diff? Thanks for reading the novel!