A leaf spring vehicle suspension system includes a chassis rail. Also included is an axle. Further included is a first stage leaf spring operatively coupled at a first end and a second end to the chassis rail, the first stage leaf spring formed of a single steel spring plate and having a first length. Yet further included is a second stage leaf spring operatively coupled to the first stage leaf spring in a stacked arrangement proximate the axle, the second stage leaf spring formed of a composite material and having a second length that is less than the first length of the first stage leaf spring.

An insert to a mold for a leaf spring comprises a substrate and a hole that extends through the substrate, A post protrudes from the substrate such that the insert, may be coupled to the mold. Further, the post covers the hole on a first end, so the hole is not exposed. On the other end of the hole, a thin overlay that covers the hole. Thus, during a process where resin is added to the mold, no resin enters the hole. The insert, when added to a leaf spring, offers reinforcement on areas where there is high stress. Therefore, holes may be added to a leaf spring at areas of high stress without overly weakening the leaf spring.