Choosing a constant load spring for my 4WD

When lifting a 4WD vehicle, selecting the correct constant load spring rate is essential for maintaining optimal handling, ride quality, and suspension performance. The spring rate determines how much weight a spring can support and how it will respond to changes in load. This guide will help you understand the importance of selecting the appropriate constant load spring rate for your lifted 4WD vehicle and how it can affect your vehicle's performance and comfort.

Understanding Spring Rate and Its Importance

Spring rate refers to the stiffness of a spring, measured in pounds per inch (lb/in) or newtons per millimeter (N/mm). It indicates how much force is required to compress the spring by a certain distance. The spring rate plays a crucial role in determining the ride quality, handling, and overall suspension performance of a vehicle.

Importance of Selecting the Correct Constant Load Spring Rate

  1. Maintaining Ride Quality: Choosing the correct spring rate for your lifted 4WD vehicle helps ensure that the ride quality remains comfortable and compliant, even when carrying additional weight or driving over rough terrain. An improper spring rate can result in a harsh, bumpy ride or excessive body roll, which can be uncomfortable and potentially unsafe.

  2. Optimizing Handling and Stability: The right constant load spring rate will help maintain proper suspension geometry, even when carrying heavy loads. This allows your vehicle to maintain its handling characteristics and stability, providing a more predictable and safer driving experience.

  3. Preventing Suspension Sag: Installing springs with an appropriate constant load spring rate can prevent suspension sag, which occurs when a spring cannot adequately support the weight of the vehicle and its load. Suspension sag can negatively impact handling, tire wear, and component lifespan.

  4. Maximizing Suspension Performance: Choosing the correct spring rate will enable your suspension to perform at its best, providing the ideal balance between comfort, handling, and off-road capability. This can be particularly important for 4WD vehicles, which often face more demanding driving conditions and require greater suspension performance.

Factors to Consider When Selecting a Constant Load Spring Rate

  1. Vehicle Weight and Load Carrying Capacity: Consider the weight of your vehicle, including any aftermarket accessories and the typical loads you carry (e.g., camping gear, towing, or additional passengers). This will help determine the appropriate spring rate to support your vehicle's weight and maintain proper suspension performance.

  2. Driving Conditions and Usage: Evaluate the types of terrain and driving conditions your 4WD vehicle encounters regularly, such as off-roading, highway driving, or urban environments. Different driving conditions may require different spring rates to optimize performance and comfort.

  3. Suspension System Compatibility: Ensure that the springs you choose are compatible with your vehicle's suspension system and any aftermarket upgrades you have installed, such as lift kits or performance shocks.

  4. Professional Guidance: Consult with a suspension expert or your vehicle's manufacturer to determine the best constant load spring rate for your specific application. They can provide personalized recommendations based on your vehicle, driving preferences, and usage.


Selecting the correct constant load spring rate for your lifted 4WD vehicle is crucial for optimizing ride quality, handling, and suspension performance. By considering factors such as vehicle weight, load-carrying capacity, driving conditions, and suspension system compatibility, you can make an informed decision that will enhance your vehicle's performance, comfort, and safety.