Making Changes To The Plans

I can’t find quite the right plans for the trailer I want to build.  Can I make changes to the plans at Mechanical Elements to fit my needs?

Answer:  A qualified yes.  It really depends on what changes you have in mind.  We encourage customizing the plans.  Because – Hey, making the exact trailer to meet your needs is the best reason for DIY anyway!  And, that goes for other projects like a Gantry Crane, or a Can Storage Unit, too.  On the other hand, there are some things you should not change.

Let’s look at some real examples of what is OK to change, and what is better not.  Also, we definitely recommend the article When Is It Safe To Customize The Plans.  It gives general guidelines about where it’s safe to make changes to the plans.  Yet, for this post, we will look at some specific examples – which come from your questions.

Example 1:  Change A Utility Trailer To Off-Road

Utility 5x10 Trailer Plans - 3500 lbs
Mechanical Elements 5’x 10′ Utility Trailer shown some of the many options.  When making changes to the plans, adjust other details to fit – like the tongue jack, tailgate and fenders.

Reader Question:  “I see you have plans for a small off-road trailer, but do you have plans for a 5×10 0ff-road?”  Of course, trailer size varies when this question comes up, but the context is basically the same.

Answer:  We say YEAH BABY!!  Get out there in the woods and take your best DIY with you.

Here is a more complete answer for this Question.  We do have plans for a great 5 x 10 utility trailer.  And, we have plans for a lightweight camper chassis in a 5 x 10 size.  Changes to the plans can certainly include greater ground clearance with larger and more aggressive tires.  If that’s what you mean by ‘Off-Road’, then YES, you can do that!  Here’s how.

Start with oversized tires for increased ground clearance as well as for some lift.  Big tires will look great with your off-road vehicle!  Use matching wheels and tires for an even cooler look.

Next, use a straight axle, not a drop axle.  That makes a big difference in under trailer clearance.  (OR, for a torsion axle, use one with neutral angle down.)

If that’s not enough lift, use an Overslung Axle configuration (instead of an underslung version), which will raise the trailer frame a few inches.  This will increase your approach and departure angles also.  If you want even more lift, add spacers between the spring mounting brackets and the trailer frame.

Three Important Cautions

First, if the trailer will have wide tires, order a longer axle for clearance of the wide tires to the frame.  Do this by ordering a wider Hub Face Distance, but leave the Axle Spring Mount Distance the same.  (Example:  Our 3500# trailers are designed for 8″ – 9ish” wide tires – 225’s or so.  If you plan to have 12″ wide tires, add 3″ to the Hub Face Distance.  [12 minus 9, then half of that on each side.])

Second, if you are adding big tires, consider up-sizing the axle capacity.  Larger tires, especially when used in off-road conditions, will increase certain forces on the axle.  An up-size of the axle will make spindles and bearings stronger.  You can keep the normal size springs for ride quality, just use them on a higher capacity axle.

Third, when lifting the trailer way up, it changes the center of gravity.  Please note the differences when cornering.  Make sure you know the tipping point when you’re seriously off-roading.

Example 2:  Deck-Over Changes To The Plans

Reader Question:  “Can I make one of your trailers into a deck-over design?”

Answer:  Let’s look at definitions.

I’m not sure what to call a typical trailer where the wheels are outboard of the main bed.  That’s the design of most of our trailers (like the image in example 1).  Does anyone know if that style has a name??

Changes To The Plans For A Deck-Over Utility Trailer?
Example of Deck-Over Trailer Style. Image from Hasco

On the other hand, a deck-over design is where the trailer deck is above the wheels, extending flat over the wheels.  See the photo.  This style allows more space on the deck, but it’s a higher deck, and the load then has a higher center of gravity.  Both types of trailers are very useful for their purposes.

For a trailer designed with outboard wheels, the main frame beams are typically at the outer edges of the deck.  That is where the axle mounts and those main beams carry the axle loads.  A deck-over style trailer has main beams under the deck, still above the axle mounts, but the deck extends out beyond the main beams – over the wheels.  That is a very different design, so converting one style to the other is more than just lifting the bed.  It’s the opposite of what many people ask:  How Can I Lower A Trailer Deck?

Other considerations are the height of the tongue, how the tongue attaches, details around axle mounting, and choices for crossmembers.  Though you could add spacers and change a lot of other things, it’s probably best to start with plans designed specifically for a deck-over.  Check out these deck-over style trailer plans.

Example 3:  Change To A Torsion Axle

Torsion Axle Changes To The Plans?Reader Question:  “Can I change the axle to a torsion type or perhaps an axle-less suspension instead of leaf springs?”

Answer:  This is not a simple answer.  If I just say No, then that leaves more questions.  If I just say Yes, then that could lead to disaster.  So, please come along as I explain how it’s possible.

First we must understand the differences in various types of suspension.  The article Trailer Axles 101 is a good start.  Second, please read this article showing the effect on the frame for Torsion Axles versus Leaf Springs.  They interact and pass stresses to the frame quite differently.  To make these changes to the plans, we must accommodate the force differences.

If we don’t compensate properly for the added stresses of a Torsion Axle, then we might have frame problems.  That’s where the potential disaster comes in.  On the other hand, if we do modify for the torsion stresses, then yes, the axles can substitute.  Here is what we recommend:  First, in our plans, the axles have a separate mounting member to avoid weakening the main frame beams by welding at the points of highest stress.  Change that member to support the new axle  . . . .  Oh nevermind!  Let’s make it easier than all that.  Just buy our Torsion Axle Conversion plans for your size trailer, and that will give you all the details.  We have already done the engineering.

Second, mount the axle so the spindles (wheels) are in the axle position.  That will place the cross beam of the torsion axle forward from there, but the cross beam position is not the important part.  The spindle position is.

For the Axle-Less Suspension, please read this article for mounting details.

Additional Axle Considerations:

For other suspension types, like this low profile trailer suspension, just note the different forces, then make the frame to handle them.  Changes to make are most easy to see by simply looking at forces the suspension will put on the trailer frame.  Adjust the design to strengthen the frame in those areas and directions.

Our twin torsion axle walking beam suspension is made to mount on any of our trailers (within the capacity) since it includes its own stress spreading members.

Example 4:  Aluminum Trailer Frame Instead?

Compare Aluminum and Steel MaterialReader Question:  “Can I build the trailer with Aluminum instead of Steel?”

Answer:  There is a big difference in the material properties of Aluminum vs. Steel.  While Aluminum is a very nice material with many benefits, plans drawn for Steel are not for Aluminum.

This is a pretty frequent question.  We recognize the benefits of aluminum and we have see a lot of really cool aluminum trailers.  There is nothing wrong with aluminum, but you need to start with plans that design for it.  The engineering is different.  Please read this article about trailer frames in aluminum.

Here is another article answering the question of Why Don’t We Have Plans for Aluminum Trailers?  There are many parts to the answer, and it is not what many people think.

Some of our Gantry Crane Plans include options for Aluminum, with the respective load and deflection curves to show the choices.  In this case, the plans show options for Aluminum, so Yes.

Yes, there are a lot of good Aluminum trailers out there.  Yes, plans for aluminum trailers exist.  Just don’t confuse the two because there are accommodations for aluminum that are different from steel.  Please read more about the engineering differences in this Article about Aluminum vs. Steel.

As A Side Note:

At Mechanical Elements we choose to design for steel partly because steel is more forgiving in both durability and in welding, but also because it is more accessible for DIY projects.  I don’t mean easier to get, I mean the whole picture.  Steel is less expensive, easier to get, and more likely for a good result without being an expert.  Tools for the project are also more common (like welding).  We focus on DIY, and our goal is to help with your success.  Perhaps we’ll have aluminum trailer plans in the future at some point.

Example 5:  Changing Size

Reader Question:  “Can I change the size of the trailer?”

Answer:  Yes, but there are important limits.

We’ve covered this question in a lot of detail in this article about customizing the plans.  There are some areas where you are free to make changes, and some areas where you should not.  Please see that article for details.

Making Your Changes To The Plans

For other real world examples of how customers have included changes to the plans, please see the Customer Stories Page.  There are several examples – especially for the gantry cranes – where modifications improve function for their specific needs.

We encourage customizing.  It’s the best reason to build in the first place, and it gets the end product you really want.  The same things don’t serve all customers.  So, use our plans as the base, then please feel free to customize and modify and make changes to the plans as you see fit.  We only ask that you stay within the bounds described here, for safety.

We wish you the best as you modify the plans to meet your needs.  Be smart with the changes, and you’ll end up with a great final product.


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