As you make your way through the automotive repair world, you will most certainly run across left hand thread. Most thread is traditional right hand thread, which means turning the nut or bolt clockwise will tighten the aforementioned object (turning counter clockwise loosens).

There are occasions where left hand thread is required. Left hand thread loosens and tightens opposite to regular right hand thread (turn clockwise to loosen left hand thread). If you have an object that is spinning, it may spin regular right hand items loose, and thus they use left hand thread.

Some fan clutches use left hand thread. The left hand side of a vehicle, particularly older and heavy duty vehicles, may use left hand thread lug nuts. Look at the studs, and you will see an “L” marked of the end of the stud to indicate left hand thread.

This hub had every lug stud broken.

left hand thread

In an attempt to remove the wheels, someone inadvertently over tightened the lugs and eventually broke each stud off. The wheel suds can be replaced, but it is costly, and time consuming.

Just keep in mind, if you can not get something apart, stop and consider why. If something seems wrong, then it most likely is. A five minute phone call may save you hours of heartache, and hundreds of dollars.

Good luck, and happy motoring.