Why Do Trailer Leaf Springs with the Same Capacity have Different Lengths

Updated 02/18/2015 | Published 02/17/2015

Question:

why is there 23 1/2inch springs and 25 1/4inch springs both rated for 3500# axle? can I use the shorter springs on a tandem trailer that is 20foot long? does it matter

asked by: Rick

Expert Reply:

Trailer leaf springs come in many different lengths and some may have the same capacity but different measurements and/or number of leaves. This is due to different configurations of trailers, axle spacing, and tire size.

Ideally you would use the same length springs that the trailer currently has. Over time, springs can flatten out some so the measurements of old springs can be slightly off of a new spring. Also when measuring an old spring you have to do so with no weight on it be either jacking up the trailer to measure or by removing the spring completely.

If you go to a shorter or longer spring than what is on the trailer now you would have to compensate with different hanger spacing, different equalizers, or different shackle straps or all of the above. If you can tell me the hanger spacing now and the length of the springs you have from the center of one eye to the center of the other eye I can determine if you will need to change anything and what parts you would need. I have included a link to our help article on double-eye spring suspension for you.

expert reply by: Michael H