How to Determine the Spacing Between Axles when Building a 4-Axle Trailer

Question:

I am building a four axle trailer what is the measurement between axles and rocker arms

asked by: John K

Expert Reply:

There are several things to consider when positioning axles on a trailer. I have included a picture that will help some but other factors include the springs and other suspension components you will be using. Also, a 4-axle trailer can potentially be a little troublesome because when turning the wheels can scrub (scrape the ground sideways). The closer the axles are together within reason the less likely this is to happen. But on 4 axles I do not think you will be able to avoid it completely.

If using hanger kit # APTT3 which is for a 3 axle trailer, the center to center distance between the axles will be 34 inches on 2-3/8 inch axles or 28-1/2 inches on 1-3/4 inch axles.

For a 4th axle you would also need an additional hanger kit # APS3, and 2 additional equalizers, # TREQE1.

Because of the scrubbing and additional stress on the third and fourth axles I strongly recommend running this by a qualified trailer builder or shop that works on trailers. It would better to go with 3 higher capacity axles than 4.

expert reply by: Michael H