About 20 some years ago the trend for off-road leaf springs moved above the axle. The consensus was that if you were going to get crazy in the dirt you needed to have a spring-over conversion. There were plenty of 4x4s still running a spring-under axle suspension, but the hardcore guys all went spring-over. Spring-over gave them great flexibility, articulation, and ground clearance. But it often also resulted in axlewrap, worn-out springs, and problems with driveshafts.
High-speed off-road guys were the first to return to a spring-under axle suspension—and with good reasons. Running the leaf springs under the axle helps lower the center of gravity, improves axle control under hard acceleration, allows the axletube to come up farther since there are no leaves between it and the frame, and with proper springs can still allow great wheel travel. Plus, most of the prerunner-style builds were less concerned with ground clearance when compared to rockcrawlers.
We’re not here to tell you to ditch your spring-over suspensions, but we don’t want you to write off spring-under as a bad option either. We visited Deaver Spring, King Shocks, and Randy Ellis Design to discuss how and why spring-under isn’t as antiquated as you might think.