Shop coilover springs and application-specific replacement coils at Black Ops Auto Works. Compare Eibach ERS/ERO references, QA1 high-travel and tapered springs, King coil springs, ARB/Old Man Emu load-specific coils and the listed road-car spring sets. Choose dimensions and rate for a custom coilover or the exact vehicle application for a formed replacement spring.
Read Diameter, Free Length and Rate Separately
Spring inside diameter identifies the supported seat/body interface, free length describes the unloaded spring and rate describes its force-versus-compression characteristic. Compare all three. The listed Eibach 0900.225.0350, for example, identifies a 9-inch, 2.25-inch-ID, 350 lb/in ERS reference.
The QA1 9HT400B reference instead specifies 9-inch length, 2.5-inch ID and 400 lb/in. A similar length does not make these springs interchangeable. Check end shape, seat engagement, installed height and the complete suspension requirements before comparing replacement brands.
Eibach, QA1 and King Configurations
Eibach ERS and ERO references include different dimensional and operating configurations. Compare main springs with any helper/tender arrangement and required coupling or seat hardware. Eibach adapters are separate components, not additional springs.
QA1 straight and tapered references have different mounting interfaces, and King springs identify their own diameter, length and rate. Choose from the exact system specification, including usable travel and compressed dimensions, rather than assuming every spring in one diameter family can be substituted.
Vehicle-Specific Road and Off-Road Coils
ARB/Old Man Emu references use vehicle, axle and supported constant-load requirements. RockJock, Superlift, Tuff Country and other listed coils have separate ride-height and application arrangements. Compare installed accessories, the actual suspension and the required companion dampers.
Dinan performance sets and the listed Grand Cherokee adjustable spring reference serve specific road-vehicle suspension packages. A vehicle-shaped coil, an adjustable-height spring kit and a straight coilover spring supply different interfaces. A spring change does not increase the vehicle’s payload, axle or towing ratings.
Coordinate Rate, Damping and Travel
Choose rate with the vehicle’s supported weight, suspension geometry, motion ratio and intended use. Spring rate at the coil differs from effective wheel rate. A universal kg/mm range for every street or track car would ignore those differences.
Check full-droop retention, installed compression, remaining travel and the manufacturer’s coil-bind/block-height limits. Pair the spring with suitable damping and the specified height/preload procedure. Inspect worn or damaged springs using manufacturer service criteria rather than applying a universal mileage or percentage-replacement rule.
Choose Your Part
- Choose a dimensional coilover spring or an exact vehicle/axle spring package.
- Compare ID, end shape, free length, rate and units.
- Check installed height, travel, seat compatibility and damping requirements.
- Review load assumptions, quantity and required adapters or companion parts.
Frequently Asked Questions
What do spring ID, length and rate describe?
ID identifies the seating interface, free length is the unloaded dimension and rate describes force change with compression. They are separate specifications that must suit the complete setup.
Are 60 mm, 65 mm and 2.5-inch springs equivalent?
No. These are distinct dimensions; 2.5 inches is 63.5 mm. Match the approved spring and seat interface rather than treating nearby sizes as interchangeable.
How do I choose rate for a custom coilover?
Use the suspension maker’s method with vehicle weight, geometry, motion ratio, intended use and damper compatibility. A model name or generic street/track label is insufficient.
How do load-specific OME coils differ from dimensional race springs?
OME vehicle references are chosen around their exact axle, application and supported load arrangement. Dimensional springs require an approved coilover/system specification.
What should I compare beyond diameter and free length?
Compare end shape, seating, rate, installed height, usable travel and block-height limits, plus the damper and required adapters or coupling components.
What should I check after changing springs?
Use the specified height/preload procedure and inspect retention, travel and clearance. Complete the required alignment and setup checks for the vehicle.
Related Collections
Coilovers · Coilover Components · Lowering Springs · Lift Springs · Eibach · QA1
