The H&R 51658-77 is a progressive-rate Super Sport lowering spring set for the 1994-2004 Ford Mustang convertible V8. It sits one step above H&R's Sport springs. Owners on user forums say the Super Sport setup gives a noticeably lower stance and tighter body control than stock springs, and that it fills the wheel gap more fully. For a drop-top, that makes it a stronger choice than a generic coupe-based kit, since owners on user forums note that the Sport and Super Sport springs, though listed for coupes, do fit convertibles, just with an uneven drop.
Confirm fitment before you order. Details vary on whether this kit covers 1994-95 convertibles, 1996-2004 solid-axle convertibles, or the full range, so check the application with H&R. The advertised drop of about 2.0 inches front and 1.6 inches rear is approximate, and owner reports differ on the actual numbers. Because lowering changes suspension geometry, owners on user forums treat caster camber plates as a required add-on and recommend lower control arm brackets to keep the rear axle loading correctly. Searchers looking for "1994-2004 Mustang convertible lowering springs," "SN95 convertible Super Sport springs," or "progressive rate springs for drop-top Mustang" will find this kit's application notes most useful when they check the details against the manufacturer's data.
Fitment for 1994-95 convertibles is not settled. Owners on user forums report that 94-95 and 96-04 Super Sport springs differ in spring rate and drop, so confirm the application with the manufacturer before ordering.
Owners on user forums describe caster camber plates as a required item when lowering a Mustang, because the lower ride height changes alignment geometry.
Owners on user forums say that with a drop this aggressive, factory shocks and struts are likely to wear out sooner rather than later. Many owners replace them at the same time as the springs.
This is a moderate DIY job that involves front strut and spindle disassembly and rear spring access, so it requires jack stands, a floor jack, and a torque wrench. Owners on user forums recommend installing caster camber plates and lower control arm brackets during the same job, since a spring-only swap leaves alignment and rear axle geometry out of spec. Replace the rubber spring isolators as part of the install, and reset the car to alignment specs afterward. Measure ride height before and after the install so you can verify the drop.
