The battery tray and the hold-down retainer should be clean and free from corrosion before installing the battery.
The battery tray should be in sound condition in order to hold the battery securely, and keep it level. Make sure there are no parts in the battery tray before installing the battery.
In order to prevent the battery from shaking in the battery tray, the hold-down retainers should be tight, but do not overtighten.