Recommendation for Adding Third Axle To Trailer Suspension

Question:

I’m not really new at this,this is the third time I’ve done a triple axel change over but the first time for 35 inch spacing. the correct spacing for the hanger spacing is 30 1/2 x 35 back to 30 1/2 using a kit number K 71 453 not the 360 information was hard to fine but this is the correct setting

asked by: Larry B

Expert Reply:

The Dexter Heavy Duty Suspension Kit # K71-360-00 is designed for 33 inch axle spacing. To add your third axle, you cannot simply add a hanger spring and axle. You can keep your 35 inch spacing but you will need to relocate your hangers. I've attached an article to help with the proper positioning of your axles.

You will need to add another equalizer of the same dimension as you have to each side and then add the same leaf springs and shackle straps as what you currently have. You will use the same hanger as your front hanger for your rear hanger. Without knowing what you have, it would be really difficult to duplicate. You may want to consider just using a kit like the Triple-Axle Trailer Hanger Kit for Double-Eye Springs - 3-1/4" Front/Rear/Center # APTT5 and the difference in your spring length will account for the difference.

For your leaf springs, you can use the 6-Leaf Double-Eye Spring for 6,000-lb Trailer Axles - 26" Long # e94SR.

I've attached the 5,200 lb axle options we carry to assist with the hub face to hub face length and the spring seat to spring seat measurement on center.

expert reply by: Jason S

click to enlarge

Larry

6/11/2018

Jason S.

6/11/2018

It is good to hear that you aren't new to this as this is a little bit of an undertaking. When using the Dexter Heavy Duty Suspension Kit # K71-360-00, you would want to space your hangers out and mock it up. The way I see it, you are wanting 35 inches at the center, but I get 31-1/8 inches on center on either end. I get this by starting with the 35 inches of your axle spacing which will make that center section the same 35 inches. Then you subtract 1/2 of once equalizer and 1/2 of the other which is 7-3/4 inches. Then subtract 26 inches on center for your leaf spring, and you will get 1.25 inches which is great for the 2.25 inch on center shackle. So when you move to the front and rear hangers you then add that same 1.25 inches for the shackle to match, add 1/2 the equalizer, and the 26 inch spring which puts you at 31-1/8 inches. I've attached the diagram to help. Let me know if you have further thoughts.