Leaf spring suspension works in unison with the shock absorbers. Leaf springs are responsible for the ride height of the vehicle and keeping the tires in contact with the road. The shock absorbers rebound and take on the impact of bumps and other road obstacles to assist the stiff leaf springs. While smaller, lighter weight vehicles use a mono-leaf spring (one single spring per side), larger, heavy-duty trucks use a multi-leaf spring suspension. Both types of suspension need to be fixed at the first signs of trouble.
Park the vehicle on a hard, level surface. The more level the surface, the more accurate a measurement of the ride height will be.
Measure from the ground to the top of each wheel well using the leaf spring suspension with a tape measure. Most often the rear axle is the only axle that uses leaf springs, but they are still present on the front of heavy-duty trucks (usually multi-leaf spring suspensions).
Compare the measurement. If one side is more or less as the other by 1 inch, inspect the lower side of the leaf spring.
Put on safety glasses and inspect the shackles of the leaf spring prior to lifting the vehicle. The shackles are located at the front and rear of each leaf spring and simply bind the spring to the frame of the vehicle. Be sure the shackles are not deteriorated by rust and are holding the leaf spring intact to the frame of the vehicle.
Lift the vehicle with the jack and place the suspension onto jack stands. If the leaf spring(s) can be inspected without lifting the vehicle, this is a safer way to go, especially on mono-leaf springs. Leaf springs are clamped to the rear axle in rear-wheel, four-wheel and all-wheel drive vehicles.
Crawl under the vehicle and visually inspect the leaf spring for physical cracks. This step is more applicable to multi-leaf spring applications since a broken mono-leaf spring application would be visibly obvious.
Run your hands down each spring, especially near the axle clamp. Oftentimes the spring will snap where it meets the axle. A broken multi-leaf spring has the chance of swinging outward, away from the spring assembly and striking the tire during operation, which can be a serious safety hazard.
- A broken mono-leaf spring is much rarer than a snapped multi-leaf spring application because, although it's a lighter weight vehicle, the spring is very strong. The main spring (lowest) on a multi-leaf spring application is also very strong, and it's usually the additional spring or springs that are compromised. If a mono-leaf spring is broken, the vehicle should be towed in for repairs. As for a multi-leaf spring, if the main spring is broken, it should also be towed; but if one of the additional springs is broken, you can tie a rope wire around it to secure it to the leaf spring assembly and drive it in for repairs. Some vehicles are notorious for shackle deterioration. This type of leaf spring damage should also be towed in for repairs.