Step 1 - Coilover Compatibility
Determine whether your suspension setup uses a coilover or a separate spring and shock. Coilover covers are designed specifically for coilover suspensions, as they need to fit securely over the spring. They will not work on a divorced setup (separate spring and shock).
In the photo, you can see a true coilover on the left and a divorced setup on the rear. The divorced configuration is more common on the rear of vehicles.
Step 2 - Consider Spring Shape & Size
Determine if your spring is a standard linear spring or a barrel spring. A barrel spring has a wider diameter in the middle, similar to the shape of a beehive. Coilover covers are only compatible with springs that have a consistent outer diameter from top to bottom. They will not fit V-Barrel or S-Barrel springs.
Measure the outside diameter of your spring to ensure it falls within 80-90mm. Springs outside this range may be too large or too small, resulting in a poor fit for the coilover covers.
Step 3 - Determine Height
Measure the distance between the bottom spring perch and the top of the spring when the wheel is at full droop. Next, measure from the top of the spring to the bottom mount locking ring. Once you have both measurements, choose a suspension cover length that falls between these two. If multiple lengths fit within X and Y, select the longer option as long as it fits within Y.