Hi
a couple of points here. There are a large number of different loctite products. They are designed for a huge array of circumstances...but the following is a guide to common requirements.
Loctite 222 (low strength, pink in colour)
Loctite 243 (medium strength, Blue in colour)
Use loctite 222 on small fasteners, say M4 and below as stronger adhesives may cause you to round off the head of your fastener. Also use this type of adhesive on low stress non safety critical or frequently removesd fasteners, as stronger adhesives will require you to work harder to clean the fastener for re-use etc.
Use loctite 243 on larger fasteners and anything safety (or cost) related, for instance the primary drive gear or the clutch hub nut etc. Note that this grade is also oil tolerant, meaning that it can be bathed in oil after curing (not that you can apply it to oily components)
Use even stronger adhesives for key tasks.
say 603 (orange high strength general purpose)
or 638 for higher temperature requirements
These high strength adhesives have fantastic capabilities so use with caution.
As far as targets for use....
most safety critical fasteners have secondary retaining devices such as stiffnuts (or nylocs), split pins, tab washers etc. so you dont need to use it on these.
Other fasteners are"safe" due to the torque applied to them creating "bolt stretch" which means that the elasticity of the bolt keeps a high friction load on the head of the fastener.
Some examples are cylinder head nuts / bolts, Engine mount bolts etc.
I would use loctite on parts that are subject to vibration, inertia, shock load or safety or cost critical areas such as..
Big end cap bolts, Oil pump mounting, camshaft sprocket, magneto nut, steering head stem nut, clutch nut, selector drum fastener, Triple clamp bolts, front axle pinch bolts. etc.
Hope this helps, i was bored so went on a bit
Dominic :blah: :blah: