Building A Trailer? – Critical Things To Get Right

There are a lot of little details that go into a trailer building project.  Some big, some small.  Overall, it is not hard, yet, when we think about the really important things that make a trailer perform well, the list is pretty short.  Give just a little extra care on these for a big pay back in success.

Maybe a list of priorities in order is the wrong way to think about it, because one item is not always more important than another.  Perhaps we should just consider the group of things that are above the “Critical” line?

(Not to say that other details are “not” important, they are, but successful performance relies on some key items.  These are the things you really need to get right if you build your own trailer.)

The “Critical” List

These are the items “Above The Critical Line” for your trailer.  Get these things right when you make a trailer, and it will perform well.  If you are buying a trailer, these are great things to check carefully too.

This list is in no particular order because they are all important.  (We have articles about most of these, so follow the links for a lot more info.)

• Start by choosing proper materials so that the trailer is strong enough to do your jobs.  This includes loading calculations or other engineering analysis to be sure.  (We don’t often think about it, but this is carefully evaluating the materials if we are buying a trailer, too.)
• Trailer architecture – how the trailer is designed – like where the beams are, and how they will carry the desired loads.  See the article on car trailer design research, then this one about truss beams.
• Use components that meet or exceed the requirements of the trailer.  Things like Axle(s), Wheels, Tires, Springs, Safety Chains, Hitch, Ball, Drawbar, and Receiver.  Some have Class ratings, some have strength ratings.  THEN, as you make a trailer, do not ever exceed the stated limits.
• When you build, make sure the welding, and skills are up to the job.  A trailer is not a good first welding project because welds are critical, and the consequences are really serious.  (Here is an example of a cracked trailer frame due, in part, to welding where it should not be.)
• If you are building, Place the trailer tongue (and hitch) on center and true to the trailer frame.
• Axle Choice, Mounting, and Position.  Choose the right axles for your application, then get the mounting right.  Finally, set the axle(s) location properly, front to back on the trailer frame.  See the article, “Where Does The Axle Go?”.
• Axle Alignment.  Make the axle(s) straight and true with the trailer and direction of travel.  And related, make sure they are mounted correctly – Single axle trailers – and equalized loading for tandem and multiple axle trailers.  Axle position and alignment is so important for towing stability when you make a trailer.
• Loading and weight balance.  Part of this is discussed in the article linked above, “Where does the axle go?”  Another big influence comes from how you load the trailer – like where you put the weight.  No matter what you tow, know where the weight is.  Then, even more information is in our Trailer Towing Tips.
• Safety Items.  Yes, most of the above include safety, but we should also mention Trailer Safety Chains and making sure you get the Chain Length Right.

Some Additional “Important” Things

This second list is for things that are not critical, but are definitely “Important”.  Here are a few more things that we could not leave out of an article like this.  To many, they actually fit the critical list.  They are not “critical” for trailer safety, but they sure can cause headaches when they are not right.

• Make a trailer frame straight and true.
• Trailer frame stiffness.  If the trailer frame is flexy, or wobbly, it can give some weird out of control like feelings as you drive.  It can also be a little weird when loading.
• Use good Tires, always.  Don’t flirt with disaster.  Tires are one of the most common failures with trailers – but most are completely avoidable.  Read the tires article, and think about having a spare tire too.
• Lights and wiring.  Again, if these are not right, it will not cause the trailer to be unstable, but it might make the police a little unstable.  Just make sure the lights are all working and meet your local legal requirements.  If you need it, we also have trailer wiring diagrams to guide the wiring – and the cord plug.
• Tongue Length.  A tongue that is too short will work, as will a tongue that is too long, but both have some problems.  However, get it right, and it will be more pleasant to tow.
• Get the trailer attitude reasonably level in all directions.  (Granted, just a little out of level does not matter much, but shoot for it.)  The result is a better ride, some saving in fuel economy, and it is a factor in towing stability.
• All the double checks in making sure the trailer is connected right, and rolling perfect each time before you take it out.
• Implement some good trailer security, if you can, by design.  A well considered approach is usually better than something slapped on after.  Make a trailer with security in mind from the beginning.  The article has some good ideas.

What Happens If You Don’t?

OK, I am sure some of the above feel like “Yeah, they are critical”, but maybe there are also questions?  So, we can also illustrate with these fun articles showing examples of failure.  Of course, they are not funny, rather, educational.  They put an emphasis on some of the above.  And hey, who does not like to learn from stories?

• We can start with an example of what happens if the materials are NOT strong enough.
• As for safety, here is a scary example of people whose lives were saved by a component that truly filled the need.  (So glad it all worked out.)
• And, a video example where the loading is not quite right, which makes the trailer is less than stable.
• Watch the video of this triple axle trailer and note what happens when the frame is not stiff enough.  (Combined with axles that do not help the situation.)
• What happens if you try to push the trailer tires a little too long?  It can make a trailer not so fun.  The hassle of failure will never make up the inconvenience of running good tires.
• Finally, I hope you nor I ever experience this kind of trailer disaster.  Or, can you imagine the horror if an unstable trailer put you in the situation of this truck over the edge?  These things happen, and that is why we emphasize the critical list of items above.

Hopefully these are a good enough reminder to take the time to make the critical things right.  True for building, and true for every day use.  Make a trailer, and use the trailer, for success.

Make A Trailer Awesome

The two above lists are not the only things that go into building a great trailer.  While these are the critical ones, we also have a bunch of articles on related topics worth reading if you are setting out to make a trailer.  Choosing the Right Bolts is one good example.

If you are up to make a trailer, especially if it is your first time, please see the many Articles from the Mechanic.  We realize there is a lot to browse through, so we included the “Show Me” search bar at the top of every page.  (And in the footer.)  Just type in a subject, then we will show you what we have on the topic.  (It works for articles as well as for project plans.)  With a library of more than 200 selections, the search feature is really helpful.

When you are ready, we have many trailer plans to help.  We can help you check off several items in the critical list, because our plans have all the engineering done, materials lists, axle placements, tongue lengths, and more.  When you are ready, the plans are here.

Thank you for joining us for a quick read.  It is all there to help those who want to make a trailer better.  We say:  Build it Better than you can Buy it!  We will help with plans, tips, and perspective.  Good luck with your next trailer build.

Did You Make A Trailer?

If you have recently built a trailer — especially if it was made from our plans — we would love to see it, and share it.  There is nothing better to inspire people in DIY than seeing other success.  Please consider submitting your story and a few photos.

Oh, and if you want some inspiration, we have some of the submissions on this Customer Stories page, and some in articles under the Customer Stories category.  Thank you.

We Hope You Have A Wonderful Day!