Determining Spring Hanger Spacing When Installing 4-Leaf Double-Eye Spring # PR4B

Updated 12/23/2014 | Published 12/22/2014

Question:

I purchased APS1 hangers and PR4B springs. If I mount the hanger per your chart the rear shackle Spring end angle would be toward the front of the trailer. The hanger spacing is 25 3/4inch and the spring hole centers are 25 1/4. Should the hanger spacing be 24 3/4? That would put the spring end of the shackle angle going to the rear of the trailer as your chart shows.

asked by: Rick R

Expert Reply:

When installing trailer suspension I recommend that you completely mock the setup to determine the best placement for the hangers. To do this I would put all of the suspension together and clamp it in place with the rear shackles at a very slight angle rearward when the trailer is lowered and wheels are on the ground.

The 25-3/4" spacing measurement that you referenced from the chart is a good starting point, but due the variance in leaf springs, hangers, and shackles, it can vary where they will perform best.

Although it seems as though your rear shackle will point toward the front of the trailer when using these measurements, keep in mind that once a load is placed on the trailer the leaf spring will lengthen. This will bring the eye center past the center of the hanger. The drawing on the attached chart represents the suspension once the load is placed.

expert reply by: Leah S