The cylinder just dropped out of my padlock and the screw that retains the cylinder fell on the floor and I lost it. What size do I need to replace it?
Answer: 5mm Countersunk M4 Bolt (in most padlocks)
Occasionally we get questions on the bolt that holds a cylinder into a lock. This is literally all it is; a simple bolt. It is not a security item but just hold the cylinder into the lock. Most of the time they are held secure with lock-tight or some other silicone. However, if they come loose and not tightened up there is a chance the whole cylinder will drop out with the risk of loosing the bolt.
If so then most padlocks use a countersunk M4 bolt with a 5mm long thread. Try and get a stainless steel one if you can. They only cost around 40p each.
5mm Countersunk M4 Bolt
