Step By Step Guide on How to Measure The Trailer Leaf Springs

Like all other trailer components, trailer leaf springs also have their specialized functions. They allow for some vertical movement of the axle so that it can absorb shocks from the uneven road surface. This, together with the fact that they serve to hold some of the trailer's weight, makes the towing of the trailer much safer. Just like other elements of a vehicle, leaf springs can wear out, suffer from sagging, or break. In this case, replacing the springs is a must, but only the correct replacement requires accurate measuring. Do not depart from this guide, as we are going to explain everything about how to measure the trailer leaf springs.

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Why Measuring the Leaf Springs Correctly is Important

According to NHTSA safety standards, proper trailer suspension is crucial. Before finding the right fit, leaf springs for your trailer, it is crucial to understand how to measure the trailer's leaf springs. Inaccurately measured or mismatched springs can lead to several issues, including:

• Excessive tire wear

• Loss of control or unstable towing

• The trailer’s poor leveling

• Poor weight distribution

For these reasons, every part of a leaf spring must be understood alongside the measuring techniques.

Various Types of Trailer Leaf Springs

Before measuring, ensure that you know what type of leaf spring you have on your trailer. Below are its most prominent types.

1. Double-Eye Leaf Springs:

These are among the most common trailer leaf springs. They have an oval eye (loop) on both ends which facilitate easy fastening and are bolted onto the trailer using shackles and hangers.

2. Slipper Leaf Springs

These has an eye on one end, and a flat or hooked end on the other which slips into a bracket or hanger. Due to their ease and strength, slipper springs are frequently used on trailers. Heavy-duty trailers have slipper leaf springs because of the strength they provide. 

Each type has a different way, even if it is by a little, to approach measurement.

Tools You Will Need

• Flexible tape measure

• Notepad or phone for recording

• Suspension unloading jack and stands

• Sockets or wrenches (during the spring removal)

• Measured Safety Eyewear and Gloves

Having the right tools will make it easier to understand how to measure the trailer leaf springs quickly and more accurately.

Step-by-Step Guide: How to Measure The Trailer Leaf Springs

According to the U.S. Department of Transportation, suspension wear is one of the top safety concerns for trailers. So I must recommend inspecting your trailer’s suspension system frequently. Some steps are mentioned below to help you measure the suspension. 

Step 1: Removing the Trailer Weight Suspension

To relieve the spring stress on the weighing the spring, lift the trailer with a jack so the axle is freely suspended. By placing jack stands under the frame, you can secure the trailer safely. While some measurements can be taken with the spring remaining on the trailer, taking the spring off is more efficient.

Step 2: Measure the Spring Length

Make sure you get the most accurate dimensions for the spring (which includes the length) as possible. Here is how to measure the length for each type of spring:

For Double-Eye Springs: 

You measure the spring length with an eye-to-eye length measurement. This means that you take the distance from the center of one eye to the center of the other one.

For Slipper Springs:

You measure from the eye’s center to the slipper’s center; to the slipper’s center. Then, if it has a hook, go to the center point of the arc of the hook.

Tip: As time passes, leaf springs may flatten or stretch due to use. If it's possible, measure old springs along with new counterparts. Accurate length measurement is key when learning how to measure the trailer leaf springs effectively. 

Step 3: Measure the Width

Width measurement needs to be done in a way that the eye serves as a fulcrum to the photo center, where the center of the spring width is located.

Leaf springs have an arboreal and free dimensional construction that grants benefits. In terms of usability, the hardware and mount springs requires some certain springs. 

In the case of leaf trailer springs, the claimed standard widths are:

• 1-3/4 inches

• 2 inches 

The hanger and sprigs attachments must align and follow standards.

Step 4: Determine the Spring Type and Mounting Style

Eye diameter: Measure the internal diameter of the eye to determine bushing and bolt sizes.

Bushing type: Springs may use nylon, rubber, or bronze bushings.

Mounting configuration: Note whether the spring is attached with shackles, brackets, or other hardware.

Step 5: Count Leaves

Now count how many blades form the leaf. Normal spring leafs have around 3-5 leaves. The load capacity of the spring is often determined by higher number of leaves. As always, check for broken or out of leaves since this may hinder performance and measurement precision.

Step 6: Measure the Camber (Spring Arch)

The camber is the vertical arch of the spring at one end without any compressing forces acting on it. Carrying out a camber measurement aids to ascertain the spring will keep the trailer at the desired height and function optimally.

To measure camber:

• Position the spring on a flat horizontal plane.

• Using a caliper, measure from the upper section of the center bolt (top of the arch) to the flat surface.

• The measurement along the vertical axis is your camber distance.

Note: If you're unsure how to measure the trailer leaf springs' arch, this is how you can measure it. If the spring is too sagged or flattened, it may not properly reflect the original camber. 

Step 7: Record Additional Measurements

Other measurements of interest are;

• The distance from the center bolt to each end or eye.

• Thickness of each leaf: Assists in estimating spring strength.

• Bolt stack height: Is likely to affect clearance.

Example: All-Around Measurement of a Leaf Spring

Imagine this scenario where you are changing a double-eye spring. Maybe your measurements can be something like this:

Feature	Measurement
Type	Double-Eye
Eye-to-Eye Length	25 1/4 inches
Width	1 3/4 inches
Number of Leaves	4
Camber (Arch Height)	3 inches
Eye Diameter	9/16 inch
Bushing Type	Nylon

The width of the replacement also matters, so while considering its length, make sure all other specifications are exact or near the area of acceptance.

Mistakes Not To Make:

• -Measuring While Under Load: Always try to discharge the spring for the sake of accuracy.

• -Guessing Bushing Size: Small variations in either the bolt or the bushing’s diameter will cause issues.

• -Making an Assumption of symmetry: Imagine springs are not symmetrical. Always measure both halves when in doubt.

• -Wearing Ignoring: Without accounting for the worn or flattened springs, misleading measurements can result. Confirm with the manufacturer if unsure.

If you really want to understand how to measure the trailer leaf springs correctly, avoid these common mistakes.

Determining when to replace trailer springs

Noticing the following could warrant such actions even if a spring isn’t technically broken:

• -Suspension dipping on one side

• -Obvious signs of corrosion or cracking

• -Creaking or squeaking

• -Tire wear, unusually high

• -Consistently scraping the bottom when crossing bumps

Should always be per axle, replacing leaf springs helps maintain balance and consistent performance.

Conclusion

When dealing with a trailer, accurately measuring the leaf springs will ensure that towing will be safe and smooth operating. In this article we have learned how to measure the trailer leaf springs. Whether you are looking to upgrade for performance or simply replacing old parts, carefully noting the measurements will save you time and money. With a few simple tools, including a tape measure, accurately purchasing a leaf spring is possible, and restoring the trailer's functionality becomes a matter of time.

In case you have doubts related to any measurement or type, it is best to check the manual of the trailer or get in touch with a vendor dealing in suspension parts. Taking such steps will enhance safety for both the trailer and the driver.