did you shim the cvd? There is a lot of play per stock instruction building. I shimmed mine up so there was no play. I shimmed them on the inside so the cvd head was deeper in the outdrive. When you first build them, after a few runs, you need to adjust them again. After that they should be fine. I have been running mine with a brushless in mod mode with no problems yet. They are starting to show wear now, but I getting somewhere around 10 runs on them before they show abuse. Maybe you got a bad batch or something.