By far, the most common trailer suspension is leaf springs. They’re cheap, straightforward, easy to repair and a bunch of other things. That said, there are definitely benefits in other suspension styles, too. Torsion is the 2nd most common with some other benefits. So, what does it take to make a Torsion Conversion?
Before you build is the best time to make the axle decision, but it’s not always the way it happens. Of course, our focus at Mechanical Elements is helping you build great stuff. So, let’s talk about converting from one axle type to another.
Before we get into converting, I’ll just remind you about the foundation articles with the background info. First, the article Axles 101 which talks a lot about axle features. Second, there’s the article that discusses various types, with a focus on multiple axles, but it gives a lot of good background.
Finally, and perhaps most important to this discussion, there’s an article about the engineering and what happens with the forces using leaf springs versus torsion axles. See the images below.
The key details out of those previous articles is how the leaf springs interact with the frame (and each other), different than for torsion axles. The mounting and the forces to the trailer frame are different. So, how do you make a torsion conversion?
Yes, some people just slap them on — one or the other as if they were universal. If things are over-built, then it might not matter, but it also means either they are hauling around a ticking bomb, or they’re hauling too much extra weight. We suggest looking at the situation with a little more care. That is where the engineering comes in.
One axle style — leaf springs or torsion — is not universally better than the other. One meets some goals better, and other axle styles meet other goals better. That is why we offer plans for both. So, choose your axle based on the goals.
I won’t go into the advantages and disadvantages of each, you can find much of that in the article Axles 101.
However, one of the big differences is how you mount them. Here are 2 images from the previous post which highlight axle mounting differences. These both represent axles mounted directly to the main frame beam and they both show issues with loading stress. Our job is to design around the issues so they are not a problem on your trailer. Our job with the Torsion Conversion plans is to show you how to go from one axle type to the other without creating areas of high stress.
Leaf Spring Trailer Axles
Torsion Trailer Axles
The way we handle it is all in the plans, and specific to our various trailers. We do the engineering for each design so it works as needed for the goals of the trailer. Handling the trailer loads is different for single leaf spring axles versus a torsion axle. It’s different for tandem axles on a Utility Trailer than for tandem axles on a Deck Over trailer. And, different based on the load capacity, and the length of each trailer. It’s especially different when going to an Axle-Less Suspension or some other style.
Torsion Axle Conversion Plans
As mentioned above, we see our job as helping you achieve your building projects. In this case, specifically with certain things like Trailers and Shop Tools. You (our readers and customers) have asked us many times for variations to our plans. To accommodate all your ideas, we could, over time, create a bunch of new plans that are nearly the same. Like the similarities of Leaf Spring axle and Torsion axles.
That is the traditional way of thinking, and we’ve done some of that. While it sounds easy enough, it means a lot of very similar plans. As mentioned in our Tilt Top Conversion article, the plans are nearly duplicates of each other. It would make a confusing Trailer Plans Catalogue for you to view and sort through.
Instead, after grappling with the possibilities, we have decided to offer the base trailer, then also offer the various conversions. Converting from a leaf spring axle to a torsion axle fits that paradigm, just like converting from a fixed tongue to a Tilt Top.
Available Torsion Conversion(s)
You will find the Torsion Axle Conversion plans in the Trailer Accessories area of the website. They are listed by trailer width for the ones they will fit.
As of now, we have conversions for our 6′ width and 6′ 10″ width, single axle, 3500# trailers. That is the nominal 6′ width which is actually wider than 6′ for a functional 6′ load as noted in the description and specifications for each of the trailers.
The new Torsion Axle Conversion Plans now go with these Single Axle Trailer Plan sizes.
Use the 6′ Width Conversion Plans with these trailers:
Use the 6′ 10″ Width Conversion Plans with these:
As of this writing, we already have trailer plans for the 4×8 – 3500# w/Torsion Axle, the 5×8 – 3500# w/Torsion Axle, and the 5×10 – 3500# w/Torsion Axle. Eventually, they will also move to this newer paradigm of the base trailer, plus the torsion conversion.
So, if you want a torsion axle on one of our 6′ width, single axle trailers, plans are now available.
(By the way, our torsion conversion is based on Dexter Torflex axles. Others will work, but some mounting holes and positions are different. We do not recommend unlinked axles in tandem — not torsion axles, unlinked springs, axle-less, or any other unlinked axles.)