The Stovebolt Site Forums The Shop Area Engine Shop Loctite vs lock washers

Your thoughts and opinions on the pros and cons of each could make for interesting reading.

i use lots of loctite on my antique motorcycles. I also use lots of thin metric wavy washers

be careful what color loctite you use, some will take heat to get off later

I've used loctite thread lockers for over 30 year in the aerospace industry. If you choose the correct product, they work extremely well. Most of them resist chemicals and moisture very well, with temperatures being the the biggest factor on it's performance.

Genericaly, there are two primary types, pernament (red in color)and an one that is easily removed (purple). There are also some adhesives for use in locking in pins, sleeves and other press fit types of application.

One thing to keep in mind, for high performance applications, red is usually the choice, and holds up experemely well in high torque and vibration environments. But if you used it in a situation where you were bolting to some large bulky object, removal of the bolt could be difficult. This is because application of heat to about 400 degrees will compromise the thread locker allowing removal of the bolt, but if you can not do this, that bolt may break before you can remove it.

The loctite website gives the specific properties of each of their tread lockers.

Lock washers are a good choice for most applications, however they may scar a critical surface, which may contribute to crack propagation. Another thing that sometimes is an issue, is that the washer elevates the height of the head of the bolt.

For troublesome applications, you may consider a nylock type fastener. These have an area milled into a portion of the threads, with a nylon insert installed. These work quite well in most applications and resist backing completely out, even if somehow they become loose. They do not require any special tools and are relatively easy to remove, though you will not be able to spin the fastener with your finger, meaning you'll have to wrench it all the way in. McMaster Carr have these as standard stock items.

The main reason I asked is that the bolts that hold my flywheel on were locked in place with a sheetmetal flange that you bent tabs up onto the flats of the bolts to keep them from backing out. Upon removal, most of the tabs broke off.

Someone suggested that they are obsolete and that Loctite would work just as well.

Czecman, those were called french locks and were also used on exhaust manifolds for years. You can use internal/external tooth washers(also called star locks)that hold up well. Your local hardware store should have them. I would not use locktite on flywheel bolts.

Why not?

Bolts tightened to the proper torque value do not need any sort of locking device, liquid or mechanical. That being said, LocTite is good insurance. The trick when using any type of liquid threadlocker is getting both surfaces clean. Even a slight film of oil will prevent the threadlocker from getting a bite on the pores of the metal.

Threadlock compounds are known as "anaerobic sealers", as they harden when out of the presence of air. As long as Loctite is exposed to air, it stays liquid. Once it's trapped in a thread it hardens. The red stuff needs heat to release it, about 400 degrees F., while the blue, green, or purple color usually responds to a firm pull and shears off without the benefit of heat. Those sheet metal lock tabs are just "feel good" devices which will not prevent an improperly tightened bolt from backing out anyway. Use the red loctite, and be sure to get the threads chemically clean, then torque them to spec and forget about them!
Jerry