Abstract: To increase the strength of a helical spring with a spring wire made of thermosetting plastic in which reinforcing fibers are embedded that run at an angle of approximately .+-.45.degree. to the longitudinal axis of the spring wire, the fibers are present as a fabric that is wound helically around the longitudinal axis of the spring wire, with the warp and woof threads being at an angle of approximately 45.degree. to the longitudinal axis. A process is also proposed for producing such helical springs.

Abstract: In order to adjust the fiber orientation of a valve spring retainer made of arbon fiber reinforced synthetic material to the stresses appearing in practical operation, it is suggested that several stacked carbon fiber tissue layers be bedded into the valve spring retainer, that a conical opening run vertical to the tissue layers through these, that the weft and warp threads of the tissue layers are displaced from the cross section of the opening to the outside and each project over a part of the perimeter of the opening and that in the edge area of the opening the displaced weft and warp threads have a greater thickness than in the areas farther away from the opening. Furthermore, a process for the production of such a valve spring retainer is discussed.