Setting Coilover Preload Correctly
At Coilovers, we’re passionate about performance suspension, specifically how you can enhance your ride using coilovers. As a car enthusiast, understanding preload is essential for anyone passionate about modifying and tuning their vehicle’s suspension system. One crucial aspect that determines how your suspension behaves is preload. Understanding and adjusting coilover preload correctly can significantly enhance handling, stability, and comfort. In this guide, we’ll explore what coilovers are, discuss the significance of preload, and equip you with the details needed to set coilover preload correctly.
Understanding Coilovers and Preload
What Are Coilovers?
Coilovers are advanced suspension systems that combine shock absorbers and coil springs into a single unit. When installed on an Infiniti, proper setup is essential to ensure the spring and damper components work together for optimal performance. Coilovers allow for independent adjustment of ride height and spring preload, making them a popular choice among performance enthusiasts and racers. Having separate ride height and preload adjustments is often a hallmark of higher-quality, performance-oriented coilovers. With these tuning options, Infiniti owners can optimize handling, ride comfort, and overall driving dynamics across a variety of road conditions. Ultimately, it is the user’s responsibility to fine-tune the suspension settings to best suit their vehicle’s needs and driving style.
The Importance of Preload in Suspensions
Preload refers to the initial compression applied to the coil spring when it’s mounted on the coilover system. When preload is set, the spring compresses slightly even before the car’s weight is applied. Most coilover springs are linear, meaning the spring rate—the force required to compress the spring a certain distance—remains constant as the spring compresses, unless a variable rate spring is used.
It’s important to understand the difference between preload and ride height adjustment: preload affects how much the spring is compressed and influences suspension travel, while ride height adjustment changes the car’s stance without necessarily altering spring compression. Spring length also plays a role, as shorter springs can reduce suspension travel and make the ride firmer, impacting ride quality. Too little preload can lead to sloppy handling and noise over bumps. If preload is set incorrectly, you may hear clunking or other unusual noises from the suspension, indicating improper operation.
This critical adjustment holds several benefits:
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Prevents Unseating: Proper preload keeps the coilover spring from completely unseating, which can lead to instability during turns. An unseated spring may cause handling issues and affect the vehicle’s overall balance.
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Optimizes Performance: Every suspension spring is engineered to perform optimally under specific preload conditions. Similar to how an engine operates best at certain RPMs, the coilover system functions best at its designated preload settings. Following manufacturer specifications ensures that the setup operates as intended.
When adjusting preload and ride height, pay close attention to how the car sits after changes are made. Adjusting the spring platform directly influences the way the vehicle sits, affecting both its stance and handling. The spring and damper work together to achieve the desired sit of the car, making this a key indicator of proper suspension setup and ride quality. Increasing the preload on a coil spring will reduce the amount of travel the suspension has when the vehicle takes on weight. Do not use preload to adjust the car’s ride height on coilovers with independent height adjustment; use the dedicated height adjustment feature instead.
Factors Influencing Preload Settings
Weight Distribution
Weight distribution is pivotal when considering preload settings, as the load on each corner of the car can affect the required preload setting. Different vehicles carry weight differently, factors like a full gas tank, added aftermarket components, or even passengers can alter weight distribution. As a result, one side of your vehicle might require more preload than the other. It’s completely normal to see one coilover showing more threads than its counterpart as a means to correct this imbalance.
Driving Style and Conditions
Your driving style and the conditions you encounter play significant roles in determining the right preload. For example:
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Street Driving: Typically, a preload of 20-40mm is advised, providing a comfortable balance for everyday driving.
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Increasing preload can increase suspension stiffness, which may be desirable for track use but less comfortable for street driving.
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Track Use: If you’re hitting the track, a lower preload of around 10mm may be more suitable, effectively enhancing responsiveness during aggressive maneuvers.
Vehicle Specifications
It’s important to understand that preload adjustments do not directly translate to lift on vehicles with independent suspension systems, including many Jaguar models. Ride height should be adjusted using the spring platform to raise or lower the vehicle, rather than altering the damper body. Adjusting the spring platform changes the unsprung length and directly affects how the car sits on its suspension. Setting ride height via the lower spring platform helps maintain the correct bump-to-droop ratio, which is essential for proper handling and ride quality. As a general guideline, about ½ inch of preload typically results in roughly 1 inch of lift at the wheel, though this can vary depending on a Jaguar’s specific suspension geometry—making precise measurement and careful adjustment especially important.
How to Properly Adjust Coilover Preload
Tools Required for Adjustment
Before diving into the adjustment process, make sure you have the right tools on hand. A jack is necessary for lifting the car, and a spanner wrench is essential for rotating the preload collar. Some coilovers, like those from King, may come with specific punch-style tools, while others might not include them.
Step-by-Step Adjustment Process
Basically, setting coilover preload involves lifting the vehicle, loosening the necessary collars, adjusting the spring perch to achieve the correct preload, measuring the compression, and securing everything before lowering the car. This straightforward process ensures your suspension is set up for optimal performance.
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Lift the Vehicle: Use a jack to lift the car until it is entirely off the ground, allowing for full extension of the shocks. Adjusting preload should be done while the suspension is unloaded (i.e., when the car is lifted and the wheels are off the ground). Pay special attention to the rear coilovers, as they may require additional steps or care during setup.
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Loosen the Bottom Locking Collar and Spring Perch/Seat Collar: Before you adjust preload, loosen the bottom locking collar and the spring perch (seat collar) to begin the preload adjustment process.
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Loosen the Locking Ring and Spring Perch: Loosen the locking ring and the spring perch to allow for movement and adjustment of the spring.
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Set Preload by Rotating the Spring Perch and Ring: Use a spanner wrench to rotate the spring perch and ring, compressing the spring to adjust preload. Start by making the spring just snug against the perch, then add a small, specific amount of preload. Preload should be set to 7–10mm to target the advertised spring rate of your coilovers. This step is crucial to achieve the correct spring tension and target the advertised spring rate of your coilovers.
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Measure Spring Compression in Inches or Millimeters: Take measurements to determine how much the spring has been compressed before any weight is applied. Common preload standards are 4–5mm for many street setups, while some manufacturers suggest 7–10mm for specific performance applications. Always measure from the free length of the spring for accuracy. Using data—such as measurements, manufacturer regulations, or experience—helps achieve precise and compliant ride height and spring positioning.
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Check Shaft, Stroke, Bump, Droop, Bump Travel, and Droop Travel: Ensure the damper shaft, total stroke, bump travel, and droop travel are within the optimal range. Coilovers with two points of adjustment allow for fine-tuning of the bump to droop ratio of the damper stroke. When adjusting ride height, maintain the same amount of bump and droop travel by using the spring platform (not the damper body). The goal is to achieve the correct bump/droop travel for optimal handling and ride quality.
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Adjust Ride Height Using Lower Mounts and Mount Positions: Adjust ride height by raising or lowering the lower mounts or mount positions, which changes the spring’s position relative to the chassis. The entire body of the shock is threaded, allowing independent adjustment of preload and ride height.
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Secure All Locking Rings and Collars: After all adjustments, lock all rings and collars to prevent movement. This includes the locking ring, spring perch, and any other adjustment collars.
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Note on Top Adjustment: The very top of the coilover may have an adjustment screw for fine-tuning shock stiffness, rebound, or damping.
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Reinstall the Coilover: Properly reinstall the coilover and torque all hardware according to specifications.
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Lower the Vehicle: Gently lower the vehicle and let the suspension settle to account for any changes.
Note: Accurate measurements and locking all components are crucial for safety and performance. Always double-check that the spring is seated correctly at every point and that all rings and collars are locked after adjustment. For a visual demonstration of how to adjust preload and set up your coilovers, watch a video guide to see each step in action.
Common Mistakes to Avoid
Over-tightening vs. Under-tightening
One of the most frequent errors made during preload adjustments is incorrect torque. Over-tightening the preload can severely reduce the spring's effectiveness, leading to a harsh ride. On the opposite end, if the preload is too loose, it runs the risk of the spring unseating, leading to dangerous handling issues. Remember, preload should always be measured based on spring compression and not merely by the visible threads.
Ignoring Manufacturer Specifications
Every spring has its designated preload specification provided by the manufacturer. Operating springs outside of these recommended conditions can lead to compromised performance and may greatly affect the durability of the suspension system.
Testing and Fine-Tuning Your Setup
Road Testing Techniques
Once you've made your adjustments, it's crucial to put everything to the test. Take a drive on a flat, level surface, allowing the suspension to settle and adjust gradually to your changes. During this time, monitor how the vehicle handles. It's important to measure shock lengths and then compare them to your target ride height.
Adjusting Based on Feedback
After your initial test drive, iterative adjustments may be necessary. Be prepared to make small changes in preload, as each increment can create significant variances in performance. Keep track of adjustments made, so you can return to a previous setting if needed.
Setting the preload correctly on your coilovers is vital for achieving the desired performance from your suspension. By understanding coilovers, knowing the influence of weight distribution and driving conditions, and following a systematic approach for adjustment, you can enhance the ride quality and handling of your vehicle effectively. At Coilovers.com, we're here to assist you every step of the way in upgrading your suspension.
Frequently Asked Questions
What is coilover preload and why is it important?
Coilover preload refers to the initial compression on the coil spring within the coilover system. It's important because it prevents unseating of the spring, optimizes vehicle performance, and enhances handling stability.
How do I adjust the preload on my coilovers?
To adjust coilover preload, lift the vehicle, loosen the preload set screw, and use a spanner wrench to rotate the preload collar. Make sure to measure spring compression correctly before securing everything back in place.
What factors affect the correct preload setting for coilovers?
Factors influencing preload settings include weight distribution of the vehicle, driving style (street vs. track), and specific vehicle specifications. Each aspect can require unique adjustments to optimize performance.
Can I set coilover preload without professional help?
Yes, adjusting coilover preload can be done at home with the right tools, like a spanner wrench. However, it's important to follow manufacturer guidelines and test the setup for desired performance to ensure safety.
What are common mistakes to avoid when setting coilover preload?
Common mistakes include over-tightening or under-tightening the preload. Both can lead to performance issues or safety risks. Always consult manufacturer specifications for the best results.
How do driving conditions influence coilover preload adjustments?
Driving conditions impact preload settings, with street driving generally recommended at 20-40mm preload, while track use might require lower preload around 10mm for enhanced responsiveness in aggressive maneuvers.