How to Set Coilover Preload

1. With the front or rear of the car jacked up, put the car on jack stands, with both front or rear wheels off the ground at the same time. 
2. Loose the lower spring seat ring. This is done by either loosening the lower spring seat lock ring, or loosening the spring seat lock ring hex head bolt, if there is only 1 lock ring. 
3. Use the spanner wrenches that came with the kit to remove the spring preload completely. The spring should be loose and able to move up and down by hand. 
4. Once preload is completely removed, use your hand to bring the spring seat up to the bottom of the spring so the spring is touching top and bottom, and cannot be moved up or down by hand. 
5. Use your hand ONLY and rotate the lower spring seat up compressing the spring as much as possible by hand. 
6. Once you cannot turn the ring by hand anymore, you have “zero” preload on the spring and this is where we start adding preload. 
7. If you have two rings below the spring (a lower spring seat and spring seat lock ring), rotate the smaller of the two rings up to the lower spring seat right to where it touches, but is not tight. You can use the spring seat lock ring as a measure of how much preload you have added by checking the space between them as you add preload to the spring with the lower spring seat. 
8. If you have only 1 ring, measure the spring from top to bottom and note the measurement. 
9. Use the correct spanner wrench and begin adding preload to the spring and keep adding preload till you have compressed the spring 5-8mm. The amount of preload needed varies by manufacturer but 5-8mm is a good rule of thumb if you’re unsure. 
10. If you have two rings below the spring, a lower spring seat and spring seat lock ring, measure the distance between the two rings to determine how much preload you have added, the thickness of the spanner wrench is a good rule of thumb. If the spanner fits between the two rings then you have enough preload, if it doesn’t fit, add more preload and till you can fit the spanner wrench between the two rings. 
11. If you have only 1 ring below the spring, measure the spring from top to bottom, being sure to measure in the exact same spot, and ensure you have added 5-8mm of preload. 
12. Once the correct amount of preload is added and confirmed, you can tighten the spring seat lock ring against the lower spring seat (if you have 2 rings, or tighten the hex head bolt if you have only 1 ring. 
13. Preload is now set and you’re ready to put the wheels back on and take the car for a drive.