How to Choose the Correct Leaf Spring Length and Correct Positioning

Question:

I have a utility trailer with a 3000# axle. The 3 leaf spring broke from age and wear. The hangers are mounted at 21.5 inch C to C. The broken double eye leaf measures about 20.5 inch C to C. Main leaf divisional lengths as if it were flat are 10.5 inch and 10.5 inch center to eye center. Shackles are installed on the rear eye and measure 3 inch C to C. What is the optimum spring length? I need at a 1500 to 1750 pound 1-3/4 inch wide 9/16 diameter eye mounted spring. Should the shackles be leaning slightly toward the rear the top of the shackle is more rearward than the bottom of the shackle, leaning slightly toward the front the top of the shackle is more forward than the bottom, or vertical when installed on the unloaded trailer? Thank you

asked by: Jim

Expert Reply:

When choosing a replacement leaf spring for your trailer suspension you will want to choose a leaf spring that is compatible with your hangers and that has the proper weight capacity rating.

I have attached a link to our available selection of leaf springs that you can filter through. The leaf spring that matches the most with the dimensions you gave me is part # e84SR which is 20-3/8 inches long from center eye to center eye, but it is only rated for a 2,000-lb trailer axle so it is not compatible. It is okay to choose a leaf spring that is rated for more weight than your axle, but it will cause your trailer to ride a little stiff.

As far as positioning goes I have attached a helpful article as well as a picture to demonstrate how to correctly position your trailer axle.

You will want to position the shackle straps so that it is slightly leaning in towards the center of the leaf spring (see attached photo).

expert reply by: Jon G