If electric. leave as is
For comparison, here is an example of the electric brake Kelsey-Hayes axles of the 1950′s. Notice how low slung the leaf spring is, necessitating a drop axle. Shows that there is no standard one size fits all axle solution.
This brings up a good point, Kelsey-Hayes is still in business as Hayes-Lemmerz, but they don’t make any usable trailer components anymore – another chapter in the USA book of “we don’t make anything anymore, we just consume it….”
Replace just the axle
Bob Patterson chose this method to convert to electric brakes by using a Dexter axle only, reusing the existing leaf springs, much like we did on our Flying Cloud, but using an Axis axle. He also chose to use a straight axle, as the only standard option available is a 4″ drop. The straight axle will give you more body height. A drop axle would end up looking like the axle on the left.
Convert to a Henschen Axle
Here is a before shot of an axle on a 1961 Tradewind courtesy of Inland RV. Note the leaf spring axle spreads it load into the frame at two points almost 3 feet apart. The Dura-Torque axle is what is used on 1962 and later Airstreams. Replacement axles are only available from Airstream Dealers – cost is about $600-$800 depending on size. They can install them too.
An after shot of the same trailer with a modern Dura-Torque axle used on Airstream trailers today. You can see the old axle hanger eye to the right on the frame. In order to make this work, you have to weld it to an extra load distribution channel to distribute the load of the axle along the frame, otherwise the frame will eventually bend at this new localized stress point.
Note: Henschen changed the Dura-Torque axle from forged steel spindles in the late 1960′s to larger diameter cold-rolled steel. It is a wise idea to replace any of the older style Dura-Torque axles with a new torsion axle, as the forged steel continues to age and work harden, becoming brittle with time. The changeover, according to Henschen, was staggered based by size and factory, so there is no firm date. The rubber shock absorbing rods were also improved later in the ’70′s, too, plus they just wear out with time. Replacing an older axle will lift the trailer back up a few inches and give a smoother ride.
Both Dexter and Axis all now make torsion axles, giving you more options. You must get a Dexter through a dealer, and Axis can be order direct. Information on measuring is on each site. Expect some hole drilling and shock mount changes with all axle changes.
1962-1963 Airstream Henschen Axle Hydraulic to Electric
What if you have a newer (’62-’63) Dura-torque trailing arm axle (no leaf springs), but with hydraulic brakes? The good news here is that Dexter loaded backing plates will fit the Henschen hubs. Diameter of the Dexter plate is 13 3/4″, so check yours. Cost is about $120 for the parts, or about $300 installed.