Please can you inform what’s the best/correct finish for both the visible and invisible (IN THE STACK) parts of leaf springs?
A couple of people I know insist on painting them totally including all in between the leafs, the normal for them bondaprimer / undercoat / enamel topcoat layers.
(They do have to externally visually match body finish on some vehicles)
While I don’t have any expertise in this area at all (as the following may well prove!), it seems as it just chafes out in weeks from between the leafs, prevents grease type protection adhering, harbors dirt and causes more rust than otherwise…
We do not recommend that any coating of any kind be applied to the inner surfaces of a leaf spring. The coating, whether it be paint or powder coating, WILL wear off due to interleaf friction. When the coating wears off, looseness between the leaves will appear. This looseness will allow the leaves extra movement which can cause premature breakage of the leaves or cause the center-bolt to shear.
The rusting between the leaves is a natural thing caused by the interleaf fiction.
Grease has an adverse reaction to spring steel which causes the steel to degrade and weaken the spring, so we do not recommend using grease/graphite between the leaves.
The appearance of rust is something that has to be lived with. See what I had to say about Painting vs. Powder Coating vs. Chroming springs.