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How do you determine what leaf spring you have on your vehicle?

Leaf springs are commonly used in heavy duty trucks, pickups, vans and SUV’s and are a critical part of the vehicles suspension.  At some point they will reach the end of their life expectancy and will need to be replaced, but how do you determine what leaf spring you have on your vehicle?

For do-it-yourselfers, this might sound like a difficult task, but there are a couple of simple ways to identify your leaf spring.

O.E.M. Part Number

One method of identifying a leaf spring is using the O.E.M. part number.  O.E.M or stamping numbers are located on various areas of the leaf spring.

Full Taper Spring stamping numbers can most commonly be found on the end of the first leaf.  Other locations include the side, bottom or top of the clip, or at the end of the wrapper.

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Multileaf Springs stamping numbers can most commonly be found on the side, top or bottom of the clip.  They may also be found on the bottom of the last leaf beside the center bolt or on the end of the shortest leaf.leaf-spring-1
Trailer Leaf Spring stamping numbers are found on the outside of the hook.

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In many cases, the stamping number may contain only a part of the O.E.M. part number.  Ford usually only stamps the prefix and the suffix. The base must be added to complete the part number. For example F3HT5310JA, D7HT5560AUA or D1TA5588AA, whereas 5310 represents a front spring position, 5560 a rear position and 5588 a helper spring.

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Identification by Spring Dimensions

A second method of identifying a leaf spring is by the spring’s dimensions.  This is by far the most difficult method, but can be used if no stamping number is found or is unreadable.  Five measurements will need to be taken to determine your leaf spring model.

The first measurement is the Main Leaf Length.  Leaf springs come in different types and will require a particular way to measure that style of leaf spring.

For an Eye to Eye style leaf spring, measure from the center bolt to the center of the eye in both directions along the arch.

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For an Eye to Slipper style leaf spring, measure from the center bolt to the center of the eye and center bolt to the end without, along the arch.

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For a Slipper to Slipper style leaf spring, measure from the center bolt to the end in both directions along the arch.

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For a Camel Back style leaf spring, measure from the center bolt to the end of the main leaf in both directions along the arch.  This is for Mack trucks only.

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And for a Single Point style leaf spring, measure from the center bolt to the end of the main leaf in both directions along the arch.  End hole size and distance from the center bolt must be checked.

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The second measurement taken is the Leaf Spring Width.  This is measured at the center bolt from side to side across the leaf.

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The third measurement is the Pack Thickness.  This is measured at the center bolt down the side of the spring including all leaves, tow eyes, shock eyes and pads.
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The next measurement is the Leaf Spring Arch.  Again, depending on the leaf spring style, a particular measurement must be taken.

For an Eye to Eye leaf spring, use a straight edge to mark the center of the eyes and measure the arch at the center bolt.  Always measure to the top of the main leaf and do not include any pads or spacers.

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For an Eye to Slipper leaf spring, use a straight edge to mark the center of the eye and the top of the slipper and measure the arch at the center bolt.

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For a Slipper to Slipper style leaf spring, use a straight edge on the top of the slipper ends and measure the arch directly over the center bolt.

Leaf Springs

For Camel Back style leaf spring, use a straight edge to mark the top of the main leaf in both directions and measure the arch at the center bolt.

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And for Single Point style leaf springs, use a straight edge to mark the top of the main leaf in both directions and measure the arch at the center bolt.

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The final measurement is the Eye Leaf length.  This is measured from the center of the eye to the center bolt along the arch.

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Whether you use the O.E.M. part number or measurement method, you will have the necessary information needed to replace your leaf spring.  Let one of the suspension experts at NewTruckSpring.com help you with your leaf spring selection Send mail:wabco@wabco.cn visiting us online at NewTruckSpring.com