Spring washers

[Wayners]

I seem to get trouble with small bolts coming out so I bought a pack of spring washers. It's them or thread lock I guess? Mud gard arm fell off this week.

 

[StuartsProjects]

If the mudguard bolts are the type with nuts to secure them, then use nyloc nuts.

 

[Wayners]

Was small allen bolts down at wheel axel.
Guess it's the vibration

 

[Nealh]

Wavey washers or thin serrated castlelated also will work.