The pedal is given the spring action by using a rubber ball with its ends cut away. Go for a very soft rubber ball and cut off it's two end surfaces as shown in the picture. Now place the ball beneath the pedal. In order to prevent the ball from slipping away, glue a wooden bar piece near it's front. You can also use superglue to bind the ball on to the plywood.

Now insert a pin at the top end of the pedal and tie a string to it. The other end of the string has to be fastened to another pin driven into the plywood base of the gaming / racing wheel. The string can be adjusted to make all the pedals aligned down equally even when no pressure is applied.