Hanger Distance for Installing 25-1/2 inch Leaf Springs with Hanger Kit # APT8

Question:

I have the APT8 hanger kit and four one-leaf double-eye springs for 3 inch diameter 6000 lb axles. The center to center measurement on my springs is 25 1/2 inches. Do you have a chart of what my hanger distances should be? The spring holes measure 11/16. Do I need bushings for them to use the 9/16 bolts that came with the kit? What is the recommended torque for the shackle bolts in this kit and also for the u-bolts that attach the springs to the axle? Thanks!

asked by: Jalina

Expert Reply:

To determine the location for the front and rear hangers on your tandem axle trailer you will first need to make sure that you have the correct center point for your equalizer hanger.

The center point of your equalizer hanger needs to be located where you will have 60 percent of the frame of the trailer in front of the center of the equalizer hanger and 40 percent behind the center of the equalizer hanger. For example, if the trailers frames length is 10 feet, then the center-line location for the equalizer hanger will be 6 feet from the front of the trailer and 4 feet from the back.

I am including a good picture of the measurements that are required on a tandem axle and a chart that will list the hanger distances on a 2,000-lb axle and a 3,500-lb axle. The picture is from the product page of the Tandem-Axle Trailer Hanger Kit for Double-Eye Springs, part # APT1. This kit uses an 8 inch long equalizer and the leaf springs listed for a 3,500-lb axle have a length of 25-1/4 inches. If your leaf springs have a length of 25-1/2 inches you will need to add a 1/4 inch to the front hanger distance and the rear hanger distance, and then add an additional 1/4 inch for your longer equalizers included in your # APT8 kit.

I am including links to some FAQ pages on trailer suspensions and leaf springs.

For the 9/16 inch diameter bolts a torque rating of 65 to 95 foot pounds is right where you want to be.

You will first want to determine if your u-bolts on your leaf springs are 3/8 inch or 1/2 inch u-bolts. The torque for the u-bolts are a minimum of 30 ft-lb and a maximum of 40 ft-lb for 3/8 inch u-bolts or a minimum of 45 ft-lb and a maximum of 60 ft-lb for 1/2 inch u-bolts.

expert reply by: Jameson C