Tacoma / 4Runner – Coilover Preload FAQ

What is preload?

Preload is the initial (pre) tension (load) on your springs before carrying the weight of the vehicle. Coilover spring preload is measured in inches, in other words, how many inches have you compressed the springs before applying weight. Ex: A 14″ long spring that measures 12″ tall when installed on the coilover has 2″ of preload.

NOT preload

Preload is not equal to the amount of threads showing on a coilover. Threads showing is almost never referred to when measuring a coilover setup. Spring length and weight rating will affect the amount of preload needed on a coilover to get the desired ride height.

How much preload do I need for 1” 2” 3” lift?

Calculating exact preload to lift height is extremely complicated due to model year changes, trim level changes, variations in accessory weight, and variations in the left to right weight balance. For this reason we do not have a specific preload number for each vehicle.  To achieve your desired ride height it is best to install coilovers as-is, then adjust accordingly. Remember these coilovers do not have unlimited height, make sure you are aware of your coilovers collapsed length, max recommended installed length, and extended length.

Do my coilovers come preset to lift height?

Coilovers come set from Fox and King preset to their specs. Most of the time they will need to be adjusted according to your vehicle. Unfortunately this something we cannot adjust prior to shipping you the shocks. When you receive your coilovers, there is a LEFT and RIGHT side, the driver side should have a little more preload than driver side. This is normal.

DIY: How to set preload on your coilovers?

-Measure on the eye to eye length of the shock & determine how much higher or lower you want it.

-Measure the exposed threads above the preload nut (record this measurement)

-Lift front of vehicle until no weight is on the coilovers (or remove them from the vehicle)

-Thread the preload nut up or down to achieve desired ride height

-Using a spring compressor with the shocks off the vehicle will make this much easier

-Check that you have not exceeded the max compressed length of the spring

– Adding too much preload can cause the spring to go solid before the bump stops bottom out

Too much preload?

If you find yourself needing too much preload on the coilover to get your desired lift height, you may need a heavier spring. Check out Spring Rates Article to see if you might need a heavier spring.

MAX coilover length from the top of the top hat to center of lower shock bolt at ride height = 21” for the part numbers below. (Reference Shock Length Diagram here)
FOX-883-02-418
FOX-883-06-418
FOX-883-02-130

Will cranking down the preload / lifting my truck higher make the ride rough?

Adding more preload to the coilover will not change the valving or the way the coilover shock moves. However, too much preload will force the shock to top out quicker, which could result in a harsh ride. We recommend a minimum of 3” of droop at the wheel for IFS front ends.