All ZEAL coilover systems currently use X-Coils. It seems that most Japanese, race-bred companies use linear springs produced from a cold-wound process. The X-Coil uses only a cold-wound process. What sets the X-Coil apart is that the shape of the wire is jelly-bean or egg like. It’s difficult to tell from this photo, but it’s not perfectly round and is a bit wider and fatter than others. The shape of the X-Coil wire helps maintain stability and decreases the chance of unwanted tendencies during coil bind and recovers without creating an abnormal spring shape after experiencing coil bind. You can sort of imagine how a wider, fatter wire maintains better than a perfectly round wire after coil bind. This shape as well its special material blend aids in maintaining a longer life. The X-Coils special blend of materials helps to create a very linear spring that reaches its intended spring rate quickly, accurately and smoothly. It’s vacuum-like feel helps to absorb impact from road imperfections without any unwanted harshness while maintaining a certain softness. Much of the quality of the ZEAL coilover system is due in large to the quality of the X-Coil spring.
ZEAL also produces the X-Coils D (”D” for Down) which are lowering springs for vehicles such as minivans and SUVs. Shown here are some for the Honda Fit.