Coupling Thread Repair 

In the event that you drop your frame on the opened and unprotected coupling threads or in some other way damage the threads,  we recommend that you take your frame to a qualified framebuilder for repair.  In an emergency, it may be possible to repair damaged threads yourself with a thread file.  

Thread file

This standard thread file is used to restore damaged threads when a threading die isn't available or when a die can't be used due to space limitations.

Select the 16 threads per inch pitch.

Use the side of the file with the pitch that matches your thread.  S and S Couplings use 16 threads per inch.


Stroke starting position.

Start your stroke in this position and apply downward pressure against the damaged threads. Apply pressure only in this direction since the file won't cut on the return stroke. With each stroke of the file, allow the file to follow the radius of the threads so you don't end up with a flat spot on one side.

Remove only the portion of the thread that has been damaged or pushed into the groove where there would normally be no material.  Don't remove the good portion of the thread or the coupling may be weakened.

 If you have an extra nut of the same size , try testing the threads by screwing it onto the coupling. The nut should screw on  freely with your fingers. If your bike has two couplings of the same size, it will be easier to test your progress if you  remove the nut from the other coupling.

 If the nut has also been damaged, we recommend that it be replace since there  is no easy way to repair a nut. In a pinch, it may be possible to use a 3/8 - 16 tap like a thread file to clean up the internal threads. To do this, hold the tap in your hand with the cutting edge of the tap pressed against the threads and rotate the nut. Continue to rotate the nut until the threads are cleaned up.

Always be sure to lubricate the coupling as described in the owners guide.

No thread file available?

It may be possible to use a very small triangular jeweler's file to make the repair. Be careful to align the file with the groove portion of the thread and remove only as much material as it required to get the nut to work as discussed in the previous section. 

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