Cotter pins

Simple and effective, try it out yourself!

Cotter pin alternative for control rods

Some of the earlier motorbikes have many small cotter pins for locking the rod ends of their numerous control rods either, when the rod has a bent end, simply by inserting the cotter pin through the rod end itself (Harley Davidson) or, when the control rod has a forked end, indirectly, by locking the separate connecting pin.

When carrying out maintenance work on such a motorbike a lot of time is wasted and damage risked in trying to take out the cotter pins, not least because the cotter pins are almost always in positions which are very difficult to reach.

*Alternative locking pin

It caught my attention that on some modern motorbikes the rear wheel spindle is secured by a so-called "R"-clip. This clip consists of a circular spring part between two legs, one of which is for insertion into a hole in the spindle to be locked and the other being formed complementarily to the spindle radius to provide a stop in the directions of both insertion and removal (see Figure ).

However, the smallest of these existing clips that could be obtained was still too big to be used as a replacement for cotter pins in control rods. Moreover the smaller "R"-clips are not very effective and are liable to come loose, mainly because the risk of deformation of the circular spring part during insertion is high.

Nevertheless such a clip appeared to represent a practical alternative if made small enough whilst also providing improved clamping force and reduced risk of deformation during insertion.

The latter problem was solved by modifying the circular spring part to form a helically wound spring, which allows high flexibility and at the same time improved clamping force, even for very small diameters of the spring part. In view of the high clamping force required, high quality spring wire was first used for manufacturing the clip, but better results were obtained using safety pins which are moreover readily available in many different sizes.

If nickel plated safety pins are bought then simple cutting and bending is enough to provide a clip all ready for use! I also found that the nickel plating does not chip off if round nosed pliers are used for bending.

*Making the alternative locking pin

After cutting off the front end of the safety pin to leave the helically wound spring end and two legs there are many possible ways of bending one or both legs to adapt the clip to the required use. Because the spring action comes from the helically wound part only, the legs may be very short and can be given any position with respect to the helically wound end without loss of clamping force.

Bending the clip legs into any shape and, when finished, manipulating the clip into the required position on the motorbike is quite easy when using round nosed pliers for holding the helically wound part of the clamp.

Four varieties are shown below, of which in particular Nos. 3 and 4 gave excellent results. Other possibilities are left to the imagination of the keen restorer!

Although I have never lost a clip, I consider that, for safety reasons, the clips should not be used on brake rods.