How to Measure Your Trailer Suspension Components | Equalizers, Shackles, and Spring Bolts

Need to replace or upgrade your trailer’s suspension but not sure how to measure the components? In this video, we will walk you through how to properly measure and identify suspension parts, including equalizers, shackles, and spring bolts. Getting the right measurements is crucial for a correct axle fitting and preventing premature wear on your suspension system.

What You’ll Learn:

• How to measure equalizers (center hole to center hole)
• How to find the correct shackle length for your trailer
• How to measure spring bolts for proper fitment
• Common mistakes to avoid when measuring trailer suspension

How to Measure an Equalizer:

To measure a trailer equalizer, take your tape measure and start from the center of the left bushing eye. Do not measure to the top eye that connects to the hanger. Instead, go to the right eye directly across from the one you started at. By measuring to the center of this bushing you can correctly identify any equalizer length. To put it plainly, just measure from the center of both bushing sockets that connect to the shackles.

How to Measure a Shackle:

When measuring a trailer shackle, measure from the center of bolt hole to the center of bolt hole. This measurement will allow for a correct replacement to be identified. The reason for measuring from the center of these holes is because it’s more important to have the same distance between the eye of the spring and the equalizer, than having the same length of shackle but the bolt holes are spaced differently.

How to Measure a Spring Bolt:

When measuring a bolt for your trailers suspension, measure the total length starting from the bottom of the threads and stopping at the top of the head. Bolts that are right around 2 inches in length are always found on double eye spring suspension set-ups, and can also be found on some slipper spring suspensions. Bolts that measure 2-1/2″ are only found on slipper spring suspension set-ups.

Proper suspension maintenance keeps your trailer riding smoothly and safely. If you need replacement equalizers, shackles, or bolts, check out Blueswift Axles—America’s #1 trailer axle and parts store!

Looking for suspension parts, you can find those here!