How to Secure Bolts Using Threadlocker: Auto Clinic

Lockwashers don't work in cars. Period. The only way you can keep a bolt from coming loose is by using either a threadlocking compound or a positive locking device (such as a cotter pin). (Photo by Burcu Avsar)

I have this really nice bike rack that attaches to my trailer hitch receiver. I have to dismantle the rack to get it into my apartment and put it away, which is easy. What's hard is keeping it from dismantling itself on long trips. How can I keep the bolts from getting loose if they are threaded into holes and there is no locknut I can replace? Lockwashers just shave the aluminum off the rack and come loose.

I would use some threadlocker, either a liquid or gel. This goo is an anaerobic compound. It flows in the presence of air, but when you spread it onto the threads of a fastener and tighten down, oxygen can't get to it. The threadlocker then polymerizes and effectively keeps the fastener from turning. There are quality products from several manufacturers. They come in dropper bottles, lipstick-like tubes and gel-dispensing tubes. You'll want to get blue compound, which is the industry standard for a medium-strength product. (Red threadlocker is intended for fasteners that normally aren't removed without the application of heat and a large amount of torque.)

Start with a clean set of threads, both male and female. Use mineral spirits, or carb or brake cleaner. There is also an aerosol spray cleaner/primer that will shorten the setting time, as well as clean the threads.

Add enough threadlocker to the joint to wet the threads (usually a single drop is sufficient), then tighten normally. To remove the fastener, simply unthread it. You'll feel a fair amount of initial resistance, and then the pieces will come apart easily. Clean and reapply every time the parts are assembled.

Don't touch the bolt to the dispensing nipple on the container or you'll transfer metal ions to the plastic. That contamination will eventually render the entire vial of threadlocker useless.

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