Motorcycle Springs are not something that we normally get involved in because we are an aerospace and defense company. Having said that we get referrals from happy customers who we have solved problems for.
One case in particular was one form a company that made exhaust systems for racing motorcycles. They mounted the systems to racing bikes used at Daytona race track and other road racing tracks. The problem was that the motorcycle springs they were buying were breaking during the races. Not good especially at speeds in excess of 100 miles per hour. They came to titan in search of a solution and after some discussion we came up with a custom spring for them.
The exhaust was mounted to the bike using a typical extension spring allowing the pipe to bounce up and down slightly.
The problem arouse because the pipe also moved torsionally which created stress on the hooked ends. The twisting motion created stress at the base of the hook. This resulted in a crack which led to the spring breaking.
In order to accommodate the travel of the spring vertically and torsionally we made a 3 piece spring. It consisted of a coiled body and two separate hooked ends. The ends have a formed eye opposite the hooks. The eye ends were inserted into the body of the spring. We then did a necking operation to taper the ends of the coiled body. This insures that the hooks would not come out. The hooks could twist and rotate eliminating the stress on the hook end while still allowing the spring to move vertically.