BMW Questions? Ask a BMW Repair Expert for Answers.
Hello and thank you for your question,Was this a new shaft you installed or a remanufactured unit?
When you install it dose it lock in place , if you pull on it dose it appear to be locked in?
If you bought it at Advance then is most likely a remanufactured unit and its either a defective unit or its not the correct one if it keeps popping out on you under load. I would contact them and have them double check it to be sure its the correct shaft and if they say it is then it has to be defective if you where not having this problem before the replacement.