My Teardrop Trailer Axle Choice

For my teardrop trailer axle I had the choice of a traditional spring axle or a torsion axle. It is the general consensus from people more experienced than me that a torsion axle gives a better ride than a spring axle. The only real detracting factor of a torsion axle is that they tend to cost a bit more than a spring axle. But for my teardrop trailer design it made the most sense to use the torsion axle. It was easier to control the trailer frame height. And it helped me get the wheel centers a little farther back because of the torsion arms. Plus I just like the torsion axle for how simple and elegant it is in appearance.

teardrop trailer axleWhich Teardrop Torsion Axle?
Once I had decided on the torsion axle, there were basically two different companies to choose from. There is either a Dexter Torflex Axle, or the UCF Flexiride Axle. The Dexter Torflex Axle that I chose is well known. It costs a bit less than the UCF axle, which is a plus. But you have to figure out your starting angle for your torsion arm, and then have the axle built with that angle set. The Flexiride axle has a spindle for the arm and you can set it to any angle you want at a later date. Also, every Dexter axle is manufactured to order at a Dexter factory and is then shipped to you. And it it generally takes two to three weeks to get it once ordered. And you always have to pay for shipping it, which in my case was a 80lbs axle and it cost about $80 to ship. A Flexiride axle on the other hand can be put together as you want it by the dealer. So you don't pay for shipping.

One reason I decided on the the Dexter is because it has a longer torsion arm than the Flexiride which worked better for my design. And I also found a great source for the axle and brake package at a great price. I got it for $294 plus shipping with brakes at KMT trailer parts.

Dexter Torsion Axle Choices?
There are a handful of things you have to figure out to place your order for your axle.

Axle Weight Rating
I choose a #9 Dexter axle, which is a 2000lb axle. I am planning on my trailer being less than 1400lbs loaded, so this sounded perfect.

Rubber Suspension Weight Rating
Next I chose to have the rubber suspension tuned to 1500lbs, which is more or less a guess about what will work good based on what others have done. It should give me a nice ride. If I had left it at 2000lbs it would probably have been a bit stiff. You can have Dexter de-rate your rubber in the axle by 100lb increments.

Mounting Bracket Distance
The next measurement I had to figure out was the outside to outside mounting bracket distance. This is basically the width of the outside of your trailer frame that you will be attaching the axle to. My trailer was going to be 60" wide, and that was what I set the bracket distance to, since I had no significant overhang of the trailer body past that trailer frame.

Electric Brakes
Since I am going to be towing the trailer with a Subaru Outback car, I decided to get electric brakes. I intend to go over a lot of mountain passes, and so the added safety in the mountains and cities will be welcome. It adds about $100 or more for the brakes, and will also require wiring in a brake control in the vehicle (another couple of hundred bucks).

One thing to note about adding electric brakes to a Dexter axle, it means you will have a longer spindle length. I had a mounting bracket distance of 60", and my hubface to hubface measurement was 74", the very least they could make it with brakes. With my zero offset wheels adding another 3" to each side, I am just over 80" on my total trailer width. Had I known this to begin with I would have reduced my entire trailer width by a couple of inches to get within 80". Live and learn.

Hubface to Hubface Measurement
This is not the easiest measurement to figure out. Basically you are trying to get your wheels pretty close to your trailer body. The things you have to know to figure it out are:

The very best thing to do is to call Dexter after you are armed with the above information. They will walk you through their program that figures out exactly what hubface to hubface measurement you will need.

dexter axle hubface

But essentially you want to know how wide your trailer is. Is it wider than your mounting brackets? If so, add that distance. Now, how big inside are your wheels? Are they big enough for the axle torsion arm to rotate within? On my #9 Dexter axle the arm is about 7.5" long from the center of where it rotates out to the end. Will that fit in your wheel? If not you have to move your hubface out far enough that your wheel clears the torsion axle arm. My arm on the #9 Dexter is 1.5" thick. So you need some space between the torsion arm and your trailer body. Add a little more space between your wheel/tire and the torsion arm. Then you have to figure in if you are using brakes or not, your wheel thickness, and if you have a wheel offset.

How to figure out your torsion arm start angle?
Your torsion arm start angle has everything to do with the height you want your trailer to ride at. This will depend on your own desires and the use of the trailer. Will it be an off road trailer and need more clearance? Will it be towed by a low car and so you want a lower hitch and ride to match? You control the ride height by the wheel and tire size, the starting angle of the torsion arm, the mounting bracket height, and whether you will be adding a side mount hanger between your frame and axle bracket.

The best answer I have seen to this question is here by Andrew on the TT&T forum. Ironically the worked example he gave was almost exactly the numbers that I was dealing with on my trailer, and so I had some confidence in what I figured out as my starting angle, which was a 22.5 degrees down starting angle.

Hub Bolt Pattern
You will have to know what type of wheel hub bolt pattern you want, because they will make the axle hubs for that. I used the common 5 on 4.5.

Mounting Method
I realized early on that I wanted to be able to remove the axle with ease in case I ever need to repair a spindle. So I opted to get the side mount hangers with my axle order. I will weld these to my trailer frame, and then I will bolt the axle to the mounts.

There you go. There are lots of things to figure out. But it is not too hard if you take your time and are careful. Time will tell if I did everything right with mine.

Now see my nice wheels