Many coilover systems on the market adjust ride height exclusively through the spring perch, meaning there’s no independent base adjustment. This design is common on high-end suspension kits and often includes a main spring paired with a very light helper spring (commonly 20–30 lb/in). To properly set these up, it’s important to understand how the helper spring works, how preload affects height and handling, and how to avoid common mistakes that lead to poor performance or unsafe suspension behavior.

Understanding the Role of the Helper Spring

A helper spring is not designed to support the car’s weight or significantly change spring rate—it’s typically rated at around 25 lb/in, compared to main springs that may range anywhere from 200 to 600+ lb/in. Its main purpose is to keep the main spring seated under droop travel and during suspension extension, preventing clunking or unseating when the wheels lift off the ground. Once the car is on its wheels, the helper spring is usually fully compressed (coil bound), leaving only the main spring to carry the load.

This design makes preload-style coilovers more usable for street cars because it prevents rattling or spring movement when the suspension unloads, but it does not change the fundamental limitation: ride height and preload are linked.

Step 1: Setting Zero Preload on the Main Spring

When installing this type of coilover:

With the suspension fully extended, thread the perch upward until the helper spring is just snug against the main spring—no slack, no vertical movement.
At this point, the helper spring will be slightly compressed (by design), while the main spring has zero preload.
This is your baseline, ensuring both springs stay seated throughout the suspension’s travel.

Step 2: Adjusting Ride Height

Ride height is adjusted by raising or lowering the perch that compresses the main spring. Since there is no separate shock body adjustment:

Lowering the car means threading the perch down, which reduces preload on the main spring. If you go too far, the main spring may go loose at full droop (though the helper spring will still keep it seated).
Raising the car means threading the perch up, which adds preload to the helper spring.

The helper spring does not significantly change these dynamics—it simply acts as insurance to keep everything seated. Rule of thumb, the more uncompressed helper spring you see (suspension extended), the lower the ride height.

Step 3: Balancing Performance and Practicality

For street and spirited driving, the goal is to run minimal preload on the helper spring while achieving your desired ride height. A good guideline is:

0–5mm preload on the helper spring beyond snug fitment. This ensures the spring is secure but not over-compressed.
The helper spring will always be fully compressed once the car is on the ground—this is normal and by design.
Do not rely on the helper spring to make up for excessive lowering. The helper’s job is only to prevent rattling or unseating, not to add usable suspension travel.

Step 4: Alignment and Safety Checks

Once the ride height is set: