A retainer comprises an inner tubular portion fitted to a mounting body. The inner tubular portion comprises an inner circular edge having a radius R3. An annular retaining surface is connected to the tubular portion. The annular retaining surface comprises an area bounded by an outer edge and the inner circular edge. The outer edge being bounded by an arc AD comprising a first radius R1, a sector CB comprising a second radius R2, where R1>R2, a first chord DC connecting the arc AD to the sector CB, and a second chord BA connecting the arc AD to the sector CB. A rocker arm assembly comprises a rocker arm body configured to actuate a valve in a valve train. The retaining surface abuts a spring coil to retain the coil against the rocker arm body, but the retaining surface does not abut a first arm of the spring.