What is a shipping bolt?

Every front-load washer ships with bolts through the back panel that hold the suspended tub rigid so it cannot swing during transport. They must be removed at installation. If they are not, the tub cannot move on its suspension and the whole machine shakes violently on spin — symptoms identical to worn shock absorbers, but free to fix. On any front-loader installed in the last few weeks, this is the first thing to check.