This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
Anyone having a bicycle coaster brake that is apparently useless because it will not brake, can easily repair it in the following manner: Remove the inner hub by unscrewing the cones and insert a piece of clock spring, about the same width as the brake shell and almost as long as its inside periphery. Replace the parts and the repair will render the brake quite as efficient as a new one. The spring serves as a braking surface for the expanding steel shoes of the brake. - Contributed by Heber H. Clewett, Pomona, Cal.