Hey Brent. Common mistakes thread?

[rbray]

All of us have made mistakes that the rest of us can learn from without reaping them.
What I propose is a thread which lists these mistakes along with a link to existing threads that discuss how to prevent them.
I will kick things off with the old lose knock off issue.

Knock off wheel torque

So many of us are novice mechanics and we just don't know what to look for until it's too late.
Let me know what you think