How to Measure Leaf Springs: A Comprehensive Guide

Replacing a Leaf Spring

On the roads of the United States, vehicles are commonly overloaded, exerting excessive pressure on their weight capacity. To counter this, leaf springs are utilized to absorb gravity and prevent suspension sag. This is particularly essential in pickup trucks where heavy items can weigh down the rear axles, affecting the vehicle’s performance on all types of terrain.

If you’re in the market for leaf spring replacements, it’s crucial to know how to measure leaf springs accurately. Contrary to popular belief, simply measuring the distance between both eyes of a leaf spring set is not sufficient. To get accurate measurements, follow these steps based on the type of spring:

Eye to Eye

To measure the length of a top spring with eyes at both ends, begin by placing your tape measure at the center bolt and extend it against the surface until it reaches the center of the front eye. While measuring, follow the arch of the spring with the ruler. Record this measurement and repeat the process, this time measuring from the center bolt to the center of the back eye. Combine the two measurements to determine the length of the longest leaf spring. Note that sometimes the two half measurements are equal, indicating that the bolt is positioned at the center. In other cases, there may be a disparity between the two measurements, indicating that the top spring extends further in one direction.

Eye to Slipper

For leaf springs with an eye at one end and a slipper at the other, measuring the overall length is similar to measuring an eye-to-eye top spring. Begin at the center bolt and extend the tape measure along the surface of the spring to the center of the eye. Take this measurement and repeat the process, this time extending to the tip of the slipper. Combine the two measurements to determine the overall length. Note that slipper ends come in different shapes, including flat end, radius end, open eye, and hook end.

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Slipper to Slipper

When measuring a slipper-to-slipper top spring, the shape of the slipper determines how far the ruler extends. On regular, flat-end, and radius slippers, the ruler ends at the physical tip of the slipper. On open-eye and hook-end slippers, the ruler extends to the outermost portion of the end. Combine the measurements from the center bolt to both ends along the arch, just like with eye-to-eye leaf springs.

Camel Back

Mack trucks feature camel-back leaf springs, which have a unique design with an upright arch resembling a camel’s back. Unlike eye and slipper leaf springs, the smallest leaf is at the top. To measure the length, start from the center bolt and extend outward in both directions, measuring the two second-longest leaves that are sandwiched by leaves of matching length.

Single Point

Heavy-duty trailers often have single-point leaf springs, which also have an upright arch design. However, the arch is slight and the top leaves are mostly flat, while the bottom leaves form a small hill. Measure the length of the bottom leaf from the center bolt in each direction.

How to Measure a Leaf Spring

Leaf springs consist of various parts that must be understood to determine the correct size for replacement:

The Springs

Leaf springs are long metal strips stacked in an inverted pyramid with the longest spring on top. They form an inverted arch held in place by a center bolt. Most leaf springs consist of three, four, or five metal strips and have an inverted arch shape. Additionally, they are bound together at quarter-lengths with clips. It’s important to check your applications as some leaf springs don’t have multiple measurements and are one size fits all.

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The Bottom Spring

Below the stacked arched springs is a horizontal strip known as the bottom spring or the overload spring. It serves as a rebound spring for the other springs and is usually shorter and thicker. Most leaf springs have only one bottom spring, but some models may have two.

The Center Bolt

The center bolt is located at or near the center of the top spring and connects all the springs in the stack, including the flat springs at the bottom. It is used as the starting point for measuring leaf springs.

The End Tips

The end tips of leaf springs are either eyes or slippers. Eyes are enclosed, curled shapes, while slippers have a flat end. Some leaf springs may have both types of ends, with an eye at the front tip and a slipper at the back.

Parts of a Leaf Spring

To determine the size of a leaf spring, you need to consider the following measurements:

  • Leaf spring length: Measure the number of inches between the tip of the front eye or slipper and the tip of the back eye or slipper. This is typically done by measuring the length of the top spring, as it accounts for the majority of the length in a set.
  • Leaf spring width: Measure the distance from one edge to the other along the top spring. The width indicates the shock absorption needs of a vehicle.
  • Leaf spring height: Measure the thickness of the springs from top to bottom, along with the space that fills the arch. Place the leaf springs upside down on a flat surface and measure the vertical distance from the surface to the bottom tip of the center bolt.
  • Leaf spring thickness: Run a tape measure vertically down the edge of the top spring to measure its thickness. This provides insight into the preferred thickness for gravity absorption.
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Find Leaf Spring for Vehicle

For replacement leaf springs, it is recommended to measure the old springs that you intend to replace. Elevate the rear of your vehicle, crawl underneath with a measuring tape and flashlight, and take the necessary measurements. Consider the type of vehicle, make and model, OEM part number, and the capacity of your current springs. Matching the weight capacity and specifications of the old springs is essential for optimal performance.

Leaf Spring Finder

Monitoring the condition of your leaf springs is vital to prevent potential issues. Look out for corrosion, cracks, leaning, and suspension sag. Rust can eat away at the metal, so replacing rusted springs before they fail is crucial. Cracks and chips also indicate the need for replacement. Leaning may occur if one spring has given out or if newly installed springs are mismatched. Suspension sag can cause discomfort while driving and affect the overall performance of your vehicle.

New Leaf Springs from General Spring

When it’s time to replace your leaf springs, trust General Spring’s wide range of sizes and thicknesses. Whether you drive a car, truck, van, or SUV, we have leaf springs tailored to various vehicle makes and models. With properly installed springs, your vehicle will have optimal gravity absorption, ensuring a smooth and safe ride.

How to Measure Leaf Spring Size for Your Vehicle

To find the perfect replacement leaf springs for your vehicle, visit General Spring’s leaf spring pages today.

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