If you are in the pondering or buying stage of your basic trailer, consider the axles. For both load weight capacities, and for common availability in case replacement might be necessary.
If at all possible upgrade from 3500 lb or less, to 5000 lb axles and suspension. Lets face it. Doing a DIY conversion. In almost all cases. The DIYer will end up with a heavier end product than a commercially built rig of comparable size and options.
Most of us DIYers do not have access to lighter materials being used in our commercially built cousins. Plus DIYers tend to want to make things more beefy and durable.
Many DIYers do not have access to welders, or the skill sets for welding aluminum. Or the willingness to go the extra cost to buy their foundation cargo trailer.
More importantly, as least to me. Especially after going through a bearing or cotter pin failure. (Evidence points to a sheared off cotter pin) A failure that resulted in a damaged axle too. I highly recommend, under whatever trailer you end up with. You have a common well known brand of axle. This also goes for the brake assemblies (though there are numerous universal replacement brake assemblies available).
Go for the types that are widely available for quick ordering and replacement. Something that can be ordered from most any shop or parts retailer. A type that is normally stocked. Or a type that is at least available and can be over-nighted. Dexter comes to mind.
My trailer I specially purchased with a “Drop or Offset Axle”. I wanted my overall trailer deck to be lower, and the center of gravity to be lower. My trailer manufacturer had that option. I actually found one on a dealers lot during my purchase process.
I really like the “drop” set-up. I still do for functionality, lower center of gravity and the safety aspect. The problem I encountered makes me rethink this whole decision for any future trailer purchase though.
I had to have my disabled trailer flat bed hauled to my home. Luckily I had roadside assistance insurance on the trailer in addition to my tow vehicle.
That roadside assistance subject can be a whole large conversation too. I can’t stress enough to really know the fine print on coverage you carry on your trailer.
A very long story, shortened here, to just point out a valuable lessen. Make sure you have axles that are common and easily available for replacement. I could not even find a replacement axle available from any shop or retailer. They could not locate one to purchase.
I went to the manufacturer of my trailer, and they had none available. (remember I have the “drop/offset axle”).
This “drop/offset axle” issue, in which no replacement was available. Had me contemplating replacing the damaged axle with a straight axle that was available the next day. But that would make me also replace my still good axle (tandem axles). Pricing out two new straight axles, springs, new hubs, bearings, brakes and other miscellaneous parts, topped $2000
Fortunately there was a sticker on the damaged axle. Giving the manufacturer of the damaged axle. Even the part number. The manufacturer was located in Salt Lake City. I was surprised when I called them. They were super accommodating. They could manufacture one from spec drawings they had computerized. The price was similar to anything that was available that was a straight configuration, but wouldn’t work on my trailer without additional expensive alterations. I paid an additional expedite fee of $50 and shipping. It was manufactured and delivered to my door about 5 days later.
In conclusion I feel fortunate this happened 19 miles from home. On the tail end of a long trip. I sat 8 hours waiting for a wrecker service that could haul the trailer. But I often wonder what mess I would have been in had I been hundreds or thousands of miles from home. At the mercy of some repair shop. Or trying to perhaps attempt a roadside repair. To find out parts weren’t available by at least the next day? All the hotel or living expenses that would have racked up in that scenario? The bill for the 19 mile flat bed ride was over $300. Luckily my State Farm roadside assistance reimbursed me for that.