How to Measure for Replacement Silpper Springs for 12K Trailer

Question:

How do you measure spring length? The ones I need to replace are about 26 5/8inch from the center of the mouting bolt hole to the end of the top leaf. Is this the right one to replace them? I assume it wouild probably be best to replace them as a pair?

asked by: Kristopher R

Expert Reply:

Given the description, it sounds like you have a slipper spring suspension. The # e74SR springs you looked at are a likely replacement, but it's best to get a correct measurement.

Generally speaking, you'll want to measure from the center of the spring eye to the highest point of the slipper end, as well as to the end of the spring, as shown in the provided photo. Because leaf springs tend to flatten out as they age, you'll want to take your measurement with the trailer up on jack stands to the axle is hanging free. You'll also want to measure the width of the springs. 1-3/4 inch is the most common, but there are also 2 and 3 inch wide slipper springs as well.

You'll also want to confirm the capacity of your axles. Most likely, your 12K capacity trailer has tandem 6K axles, but sometimes trailer manufacturers will equip trailers with axles rated for the trailer's GVWR minus their tongue weight, so positively identifying the axle capacity is important. Your axles should have tags or stickers on them to help identify them.

You will want to replace the springs in pairs.

I've linked to a help article that explains more about slipper spring suspensions.

expert reply by: Mike L