Changing coil springs in pairs is the only safe way to maintain the vehicle’s original driving characteristics. That’s the advice from leading aftermarket parts supplier, FAI Automotive.
If a spring is worn, it will often twist in its locating plate and result in a loud ‘clonk’, sometimes confused with CV joint knock. When a spring fault such as this is identified, or if the coil spring snaps, it is important that the alternate spring on the same axle is changed as well, even though there may appear to be nothing wrong with it. This is important because coil springs change their rebound characteristics over time with road use.
When new, the OE specification of the corner weight of the vehicle is as the load designed to be placed on the spring. A single new spring will not compress to the same extent and will have a lower rebound effect, which can mean that the weight it would normally support is transferred to the other wheel, or weaker spring, which, in turn, makes that spring more susceptible to future damage.
The outcome is that the car will be unbalanced, with the car pulling to one side under braking, under/over‐steer when cornering and the vehicle may present differing ride heights on either side.
In short, replacing only a single spring can cause accidents and that is why installers should educate their customers that, to be safe rather than sorry, both coil springs on an axle should be changed together.
FAI is well placed to take advantage of repairs that are increasingly common due to the poor state of the UK and Ireland’s road network. FAI coil springs are produced with top quality steel, using the latest cold coiling technology.
All parts are subject to stringent quality checks and all springs have the FAI part number printed on them for easy identification. All springs are manufactured to meet OE specification wherever possible.
FAI currently has a range of approximately 350 part numbers which cover a wide range of European and Asian vehicle applications.