Torsion Conversion – Plans To Change Your Trailer Axle

By far, the most common trailer suspension is leaf springs. They are 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 withsome other benefits. So, what does it take to make a Torsion Conversion?

The best time to make the axle decision is before you build, but that is not always the way it happens. Of course, our focus at Mechanical Elements is helping you build great stuff. So, in this article, we will talk about converting from one axle type to another. Both before you build, or after.

The Foundation

Before we get into converting, a reminder about the foundation articles with good background info. First, Axles 101 about axle features. Second, the article about axle types, with a focus on multiple axles.

Perhaps most important to this discussion, the article about the engineering of what happens with forces and stresses in a trailer frame with leaf springs versus a torsion axle.

Key details in those articles show how leaf springs interact with the frame (and each other), then how it is different with torsion axles. Forces at 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 are universal. If the trailer frame is over-built, then it might not matter. However, it can mean they are hauling a ticking bomb, or a lot of extra trailer frame weight. We suggest looking with a little more care, which is where torsion conversion engineering comes in.

Axle Choice

One axle style is not universally better than the other. One meets some goals better, then other axle styles meet other goals better. That is why we offer plans for both. Choose your axle based on the goals.

I won’t go into the advantages and disadvantages, because you can find much of it in Axles 101.

One big difference is mounting them. Below are 2 images from a previous article which show stress differences for the different axle types. They both represent axle attachments directly to the main frame beam, then colors show the stresses. Our job is to design around the high stress so it is not a problem on your trailer.

With our Torsion Conversion plans, we show you how to go from one axle type to the other without creating areas of dangerously high stress.

Typical Leaf Spring Trailer Axles

Leaf Spring Frame Stress

Typical Torsion Trailer Axles

(Don’t worry. We show you how to do it better.)

Trailer Torsion Axle Analysis

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 forces is different for leaf spring axles versus a torsion axle – and especially different for an Axle-Less Suspension. It is also different for tandem axles, and different based on the load capacity, and the length of each trailer. All these differences come into play for the engineering of our plans.

Torsion Axle Conversion Plans

Since our job is helping you achieve your goals in building these projects, . . . And, since You (our readers and customers) have asked for it, . . . Torsion Conversion is a way to get 2 axle types with one set of trailer plans.

To accommodate all your ideas, we could, create a bunch of new plans that are nearly the same. (Each trailer size repeated with different axles.) That is traditional thinking, and we have done some of that. While it sounds easy, it makes a lot of very similar plans – especially when adding in other conversions like our Tilt Top Conversion. It makes the Trailer Plans Catalogue confusing with long lists of almost the same trailers.

Instead, after grappling with possibilities, we decided to offer the main trailer, PLUS conversions. Converting from a leaf spring axle to a torsion axle fits the paradigm, just like converting from a Fixed Tongue to a Tilt Top.

Available Torsion Conversion(s)

You will find Torsion Axle Conversion plans in Trailer Accessories. The actual conversion plans list by trailer width for the sizes they will fit.

As of this writing, we have conversions for all our single axle, 3500# utility trailers, and for all our single axle, 6000# and 7000# utility trailers. These cover all the sizes from 4-ft width to the full legal 6-ft 10-inch wide deck between the wheels.

We have not yet made a torsion conversion for our lighter, 2000# trailers. They still appear separate in the list of plans. Please see the description and specifications for each trailer.

Choose Plans By Utility Trailer Width

The new Torsion Axle Conversion Plans are designed for Single Axle trailers only, and are available by Nominal Trailer Width, for specific Axle Load Capacity. Here are the links:

Use the 3500 lb. Conversion Plans to fit trailers like these:

Select the 6000 lb. / 7000 lb. Conversion Plans to fit trailers like these:

Find similar plans by viewing the Full List of Utility Trailers.

Specifications

Plans show how to convert from a standard Leaf Spring axle to a Torsion Axle.
Includes complete Drawings with all the changes in parts and materials needed for the conversion.
You will need BOTH the trailer plans AND the Torsion Conversion Plans.
(Conversion plans show only the differences.)
These plans are ONLY for Single Axle trailers. Note the load capacity.
Made for Mechanical Elements utility trailers, but can easily modify to fit other trailers also.
This conversion works with all the normal options in our trailer plans EXCEPT storing the ramp under the trailer bed. All other options work.
The Axle conversion does not change the size of the trailer.
Overall trailer length does not change.
Overall width at the wheels can be slightly different depending on axle, tire and other choices.
Weight varies with axle options. The conversion does not significantly change the total trailer weight.
A torsion axle gives more options for deck height (for more axle ground clearance or for a lower deck).
(Trailer deck height depends on your choice of the Torsion Axle neutral angle. Can be higher or lower than the conventional leaf spring suspension design.)
Follow the links to the Torsion Conversion plans ( 3500 lb. or 6000 / 7000 lb.), then select the width of your trailer to get the right plans.
Conversion plans are specifically for Dexter Torflex Axles. Other manufacturers are similar, but may need mounting modifications.

Torsions To Go

As of this writing, we are removing the (nearly) duplicate trailer plans designed specifically for 3500# Torsion Axles. They include the 4×8, the 5×8, and the 5×10. Instead, we have updated the standard plans to this new paradigm of – base trailer, plus the torsion conversion. This simplifies the process for selecting the trailer plans you need, and makes it easier to keep all the plans updated for you.

This also makes it easier to find and buy the right Trailer Parts Kit to build with.

If you want a torsion axle on one of our single axle utility trailers, the torsion conversion plans are available! Find the trailer you want in the plans store, then order the Torsion Axle Conversion Plans to go with it. Easy!

Please Note: Our torsion conversion is based on Dexter Torflex axles. Axles from other brands will also work – but you will need to adjust the mounting holes and notches for the torsion axle of your choice.

We DO NOT recommend any kind of unlinked axles in tandem or triple – not torsion axles, not unlinked springs, not axle-less suspension – nor any other unlinked axles. There are good ways to link them, and that is always what we DO recommend.

Don’t end up on the side of the road with blown bearings or a broken frame. (Link torsions with a walking beam suspension. Link leaf spring axles with an equalizer link. Or, link axles with Air Suspension.) You can even make your own linking system like this low profile linked suspension.

Retro-Fitting With A Torsion Conversion

While the Torsion Conversion plans are specifically designed to fit the Mechanical Elements utility trailers, you can certainly use these conversions with plans from other sources, or to convert an existing trailer. Some adjustments may be needed, but they are not hard. The plans show the conversion dimensions, so adjust the numbers to the width and fitment of your trailer, then it will work.

Unfortunately this requires measuring and some math, but it is simple addition and subtraction. Measure the width of your trailer (near the axle, in the same way the dimensions are given in the drawings), then add up the difference. Use that difference to modify the conversion plans, and to order the right torsion axle.

Please Note: These new Torsion Conversion plans show all the information needed to order the correct torsion axle. If your trailer is a different width, just adjust the width numbers on the plans so the axle will fit.

For Example: Our 5′ width trailer plans are actually 62″ wide at the frame. (Allows you to put 5′ width things in the trailer without scraping the sides.) Many cheap 5′ width trailers are 5′ (60″) at the frame, (or even 59″). So in this case, the axle is specified to fit a 62″ frame. If yours is 60″, then subtract 2″ from the widths specified in the Torsion Conversion plans, then order your axle.

For a trailer of the same capacity as the conversion plans (3500#, 6000# or 7000#), the new mounting brackets will be the same. Simply place the new torsion axle so that the center of the wheel is at the same location as before. Or, if needed, calculate the proper axle position for the ways you use the trailer. Hopefully you won’t need other modifications on the trailer to get things to fit.

Good Luck with Your Project !!