Using Motorcycle Threadlocker Tips And How-To

Loose hardware is a pain, and lost hardware can and will end your ride prematurely. When motorcycle vibration works against tightening torque, you need a bottle of the blue or red stuff. Today on MC Garage we talk about threadlocker.

My first two-stroke motorcycle, a 1993 Kawasaki KX250, would loosen hardware in short order. And when I moved up the KX500, if not for my diligent use of threadlocker, it would rattle itself to pieces. But not all threadlock is the same; there are different strengths and applications. So let’s get into it.

Threaklocker basically uses an anaerobic adhesive to fill the imperfections between interfacing thread surfaces to create added friction. It also fills the gaps between those threads making a completely unified assembly. Anaerobic means without air, so threadlock will not begin to harden until the nut or bolt treated with the locker is installed and is in the presence of metal ions. Once installed the threadlocker begins to cure in minutes and reaches full strength in 24 hours.

Threadlockers are available in low, medium, and high-strength formulations and are usually color coded according to their strength. Most of us are familiar with bottles of the blue and red stuff. Blue is medium strength that is best used on hardware that will need to be removed with hand tools down the line. It’s also best for small-diameter bolts. Red is high strength and is for assemblies that you don’t plan on taking apart, and when you do, it requires heat to break the bonds. There is also purple, which is below blue on the strength scale, that works great on very small hardware and materials like brass. Green is a wicking compound, meaning it will find its way into the gaps from the outside of the hardware via capillary action. It also requires heat to break the bond for easier removal.

Using red or green threadlocker in applications where thread strength is low, like with steel, stainless steel, or titanium hardware inside aluminum threads, can cause the threads to be stripped or pulled out without heat being applied. Most of the time blue is the right formulation on any external motorcycle parts. I tend to use blue on most things, and reserve red for things like footpeg brackets, exhaust hardware, and internal engine components.

So how to apply the stuff? Easy, just a couple of drops on the (clean) threads of the bolt you are installing. If it’s a through bolt—one that gets a nut or does not go into a closed (blind) hole—just put the locker at the location where the treads will be making contact when tightened. For blind holes, add locker to the threads and in the bottom of the hole. If it’s just on the bolt, air can push the threadlocker out of the hole as the bolt or screw is tightened, resulting in not enough locker for a proper bond.

A quick word on torque values when using threadlocker: Threadlocker does act as a lubricant before it cures, so it is recommended to reduce torque by 20 percent if you are torquing to values in your manual.