Top ten tips when working with leaf springs

The Diesel Technic Parts Specialists share 10 tips for when working with leaf springs.

Even in the days of horse-drawn carriages, leaf springs were used to protect the vehicle and its passengers. While vehicles may have changed over the years, the purpose of leaf springs has remained the same. Today they are an important part of the chassis, including their role as a safety feature.

Leaf springs can have a wide variety of designs. One example is a solid leaf spring package, which is mainly used in the construction sector. In this context, the lifetime of such a leaf spring is significantly longer than that of an air suspension.

An effective leaf spring plays a decisive role, as it absorbs longitudinal and transverse forces with the result that it functions as an important component of the chassis. It also provides a safe driving experience and protects passengers, cargo and vehicle components from vibrations. This is particularly advantageous on uneven terrain or in bad road conditions. Centre bolts, spring clamps and spring clips ensure that the spring stays in place.

Depending on the vehicle type, leaf springs can be used in combination with the controllable air springs to enable the raising and lowering of the vehicle.

Here are top ten tips when working with leaf springs: 

1. After repairing or replacing parts within the suspension, the axle must be measured to ensure that the wheels track correctly and are properly aligned. In the case of misalignment, it will be necessary to recalibrate. This will ensure that optimal performance and handling is achieved.
2. When replacing leaf springs, it is essential to replace them with the same type of spring. This is due to different types of leaf spring being designed to handle specific load capacities. The number of springs used, and the strength of the springs, is particularly important to prevent the risk of failure, complications due to overloading and driver discomfort. 
3. Splish-splash: always ensure leaf springs are completely clean and free from dirt, mud and deicing salt. If leaf springs are not kept clean the corrosion process can be accelerated and lead to premature abrasion. To avoid the buildup of dirt and unwanted debris, it is best to wash the underside of the vehicle as well as the leaf springs regularly with soap and water. 
4. To ensure maximum safety turn the steering wheel straight ahead in the direction of travel. 
5. Before fastening bolts are tightened, the vehicle must be lowered. The bolts must then be tightened to the torque specified by the manufacturer. This is to ensure that the spring is not installed under tension and is installed in the correct position it will experience during normal use. 
6. Ensure the correct assembly/ disassembly tools are used throughout the process.
7. Clean and sanitise the fixing holes for the bolts to ensure smooth threading. 
8. Before fitting, check that the fixing screw (centre bolt) for the individual leaf springs is tight and not loose. 
9. Spring holders are tightened with a torque. To avoid excessive stress please ensure that spring holders are not under tension after tightening. If necessary, turn the nut back slightly after the torque has been reached so that the spring holder is tension-free. 
10. For heavy commercial vehicles, it is important to check whether both sides of the suspension system are in working order or need to be replaced. If the spring is only replaced on one side, the vehicle may lean slightly as the old spring has already been subjected to a lot of strain.