How To Calculate the Weight Capacity Needed For Trailer Leaf Springs

Updated 07/13/2021 | Published 07/12/2021

Products Featured in This Question

3-Leaf Double-Eye Spring for 2,000-lb Trailer Axles - 20-3/8" Long

(2087)

$31.05

4-Leaf Slipper Spring w/ Radius End for 2,000-lb Trailer Axles - 24-5/8" Long

(633)

$42.12

Question:

Once the load of the product being trailered is calculated. How does one determine the appropriate spring rate. Example: 1,000 pound raft, should I run #500 springs or #1,000?

asked by: Tyler

Expert Reply:

To determine the correct springs you will need to know a few variables to ensure that you do not damage your trailer. You have the first variable being the load or as you suggest a 1,000lb raft. Next you need to add the weight of the trailer frame and all brackets and boards on the trailer. You will not add the axle weight as that is un-sprung weight. Say the trailer frame and components are 500lbs. This puts the un-sprung weight at 1,500lbs. Next you will need to ensure that the load does not exceed what the trailer frame and axle can support. You may need to contact the manufacturer if you are not able to find this information on the manufacturer data tag on either the trailer frame or axle.

Once you know that you have a weight that will fit into the limits of your trailer you will need to measure for the springs. There are 2 types of leaf springs, double eye and slipper springs. The double eye springs have two bolt eyelets, one on each side of the spring. A slipper spring will only have one bolt eyelet as the other side will slide on the spring perch.

An example for a double eye spring you would use is the 3-Leaf Double-Eye Spring for 2,000-lb Trailer Axles # e84SR each spring is rated for a maximum of 1,000lbs, so a set of 2 is good for 2,000lbs.

A 4-Leaf Slipper Spring w/ Radius End for 2,000-lb Trailer Axles # SP-179275 has the same weight rating but with the slipper spring it is different in the mounting and size.

Remember that when you account for the load it is better to overestimate the load but be sure that you do not exceed any of the maximum weight capacities given by the axle manufacturer or trailer manufacturer.

expert reply by: Bud M