How to Determine the Distance for Mounting Trailer Spring Hangers on a Single Axle Trailer

Updated 09/02/2011 | Published 09/01/2011

Products Featured in This Question

Front/Center/Rear Hanger for Double-Eye Springs - 3-1/4" Tall - 9/16" Bolt Hole

(302)

$12.41

Single-Axle Trailer Hanger Kit for Double-Eye Springs - 1-1/2" Front, 1-1/4" Rear

(379)

$30.34

4-Leaf Double-Eye Spring for 3,500-lb Trailer Axles

(80)

$51.99

Question:

On the double eye spring, single axle trailer how do you figure the distance for installation purposes from the center of the front hanger to the center of the shackle mount ?

asked by: Fred M

Expert Reply:

Spring Hanger location dimensions are normally figured by the manufacturer and provided with the spring hanger kit, that includes all of the parts for installing the springs on the trailer frame. I have provided a chart that shows the spring hanger locations for single axle trailers for you to review, see link.

There are two considerations for mounting the spring hangers. First, the distance between the spring hangers as you have asked about. Second, the location of the axle when installed on the springs to provide the correct tongue weight for the trailer, so it will tow properly and provide proper distribution of the load across the trailer axle.

For example, if we use the 4-leaf double-eye spring, # PR4B, which is 25-1/4 inches long, the spring hanger spacing would be 25-3/4 inches. From our chart you can see that we would use the Single-Axle Trailer Hanger Kit, # APS3. This puts the spring shackle at an angle from the hanger back toward the back of the trailer. This angle should not exceed 45 degrees if installing a spring with an unknown spring hanger spacing distance, from the spring manufacturer. Once you have the spacing figured out you need to place the two hangers so that proper tongue weight is achieved. A general rule of thumb is that 60 percent of the total trailer weight should be forward of the center line of the axle or axles on the trailer. Ideally your trailer should have 10 to 14 percent of the gross trailer weight on the hitch ball coupler.

Installing a trailer suspension requires precise layout so the trailer will be safe and handle properly without trailer sway. If you are unsure of the process a local trailer shop or welding fabrication shop can help you with installation of the critical parts. I have included an explanation on how to correctly determine axle position and figure the amount of movement needed to place the axle correctly once initial measurements have been calculated.

expert reply by: Robert G