thanks guys for all the advice. I'm not a racer so the setup isn't very important for me. The only thing I do is jump ( check my videos in my signature ) so it's all about survival !!
So far the tekno hold better than I thought. This mainshaft bending brings me back to my first 1/8 buggy with the exact same problem : the hobao hyper 9e

I won't ask any warranty because this car is meant for racing, not stupid freestyle jumps like I do ! ( video is half filmed ... )