Coil springs are deceptively simple; a length of steel formed into a helix and painted black. However, they are safety-critical and responsible for maintaining the correct vehicle ride height while absorbing impacts during travel. Constantly exposed to varying road conditions and external impacts, they are subjected to high amounts of stress as they support the weight of the vehicle, isolating it from the road.
Coil Spring Failure
The most common cause of spring failure is corrosion, as chips in the exposed layer of paint cannot be avoided. Without additional protection, the spring will immediately begin to rust, leading to corrosion under the paint which spreads rapidly, greatly reducing spring life expectancy.
The figure below shows surface defects on a spring after 1000 hours of salt spray testing. There are many small rust points, plus a large area where laser surface etching was used to apply logo and part number.
Quality or Price?
As the labour costs associated with coil spring replacement can often be more than the cost of the spring itself, it is economical to choose quality over price. Care should also be taken to assess that the spring material is of appropriate quality and the spring surface suitably protected from corrosion, to ensure it can withstand years of dynamic use.
Care should also be taken to assess that the spring material is of appropriate quality and the spring surface suitably protected from corrosion, to ensure it can withstand years of dynamic use. As illustrated in the graph, Kilen stands out from competitors with lower levels of corrosion due to Zinc elements used opposed to Iron.
Sourcing Quality Springs
The quality of the steel wire used to produce coil springs is of utmost importance as surface and inner steel defects can reduce the spring fatigue strength, leading to premature sag whilst increasing the risk of early breakage. Only a few steel mills worldwide are capable of achieving the necessary surface and internal wire quality for modern suspension springs and Kilen sources only the highest grade specialist spring steel from selected mills.
Each Kilen coil spring is manufactured in-house, checked to ensure correct fitment, and designed to match or exceed OE quality.
New Composite Leaf Springs
Kilen also produces gas and leaf springs and has recently introduced its first fibreglass resin composite leaf spring for a Mercedes Sprinter. There are some great benefits of this Leaf Spring.
- Offers a weight saving compared to traditional steel leaf springs, allowing for a slightly increased payload.
- Immune to corrosion and significantly more durable than steel springs.
FPS offers a comprehensive range of around 3,800 Kilen coil springs each benefiting from FPS’ stock and logistics support. Speak to your local representative for further information.