Shackle Standard Sizes and Compatibility

Shackle Size vs Pin Diameter

The diameter of a shackle pin is always 1/8 inch larger than the stated shackle size. The shackle size, usually shown in raised lettering on the body, represents the nominal size. To achieve the required shear strength, Factor of Safety (FoS), and Minimum Breaking Strength (MBS), the pin must be larger than the marked body size. Below are the most common shackle sizes and their corresponding pin diameters.

1/2 inch size shackle - 5/8 inch diameter pin

5/8 inch size shackle - 3/4 inch diameter pin

3/4 inch size shackle - 7/8 inch diameter pin

7/8 inch size shackle - 1.0 inch diameter pin

PLEASE NOTE: A very popular bumper mount hole inside diameter is often listed on bumper specs information as 1.0 inch. Many manufacturers use this common bore size when machining their mounts. However, after coating the entire bumper including the inside of the mount holes with thick textured or powder coatings this added thickness decreases the inside diameter of the holes well under 1.0 inch, down to around 0.950in, making the hole size too small for a 1.0 inch pin. In most cases a 1.0 inch diameter hole is intended for a 3/4 size shackle that has a 7/8” (0.875in) pin diameter. If your bumper has 1.0 mount holes please refer to our VEHICLE SIZE RECOMMENDATION GUIDES for further assistance.

 

Jaw Openings (Space between the ears)

The top sections of the shackle body where the pin passes through are referred to as the "ears" of the shackle. The space between these ears is called the "jaw opening". This opening size is a standard width handed down from the lifting and rigging industry and is directly related to maximum allowable shackle mount width sizes. Below are the most common shackle jaw openings widths.

1/2 inch size shackle - 0.88 inch jaw opening

5/8 inch size shackle - 1.06 inch jaw opening

3/4 inch size shackle - 1.25 inch jaw opening

7/8 inch size shackle - 1.49 inch jaw opening

 

Mount Width Compatibility

When selecting a shackle, it’s important to ensure the jaw opening width, also known as the space between the ears, is compatible with the width of your bumper’s shackle mount. Ideally, the shackle jaw opening should fit snugly on the mount without excessive play or the need to force it in place. A proper fit ensures even load distribution across the pin and prevents bending or wear on the shackle pin or mount during recovery operations. Below are common shackle sizes and their maximum allowable mount widths.

1/2 inch size shackle - Mount Width 0.875 inch or less

5/8 inch size shackle - Mount Width 1.0 inch or less

3/4 inch size shackle - Mount Width 1.175 inch or less

7/8 inch size shackle - Mount Width 1.378 inch or less

Mount widths rarely match standard shackle jaw openings exactly, so small gaps between the shackle ears and the mount are very common. Plastic washers are often used to fill these gaps, isolate the shackle and prevent rattling or noise during driving and off-roading. When adding washers, use only enough to fill the gap, no more. Washers that are too thick or stacked excessively can cause the pin to loosen or prevent proper thread engagement required to secure a shackle.