Two answers come to mind—not much and a heck of a lot. Not much because the body style and external finish haven’t changed. BUT a heck of a lot because continuous improvement is a way of life at Ironhorse Trailers.
Chassis—The new flip top trailers are much more rust resistant than the older ones. That’s because, when the flip top trailers were introduced in 2005, the chassis and all its steel attachments were only painted. But starting with the 2009 models, steel parts of the flip tops were powdered coated. And starting with 2014 models, all chassis part including the ones you can’t inside the tailgate, are aluminum..
Floor Material—The floors in the newer flip tops are much safer to use, much more durable and ten times better looking than the floors in the early flip top motorcycle trailers. That’s because of two big changes along the way. The half inch oriented strand board used for the floors in the first few flip tops has been replaced by ¾ inch Advantek, a far superior engineered wood with much, much better resistance to moisture and consequently a much longer useful life. These days the floor is actually a sandwich with Advantek on the bottom, fiberglass in the middle and gelcoat with a molded in non-skid pattern on top. Lower Body Construction— The floor and the rest of the inside of the newer flip top trailers not only look at least ten times better than the early ones, they also are also much safer because of the non-skid pattern molded into the floor. The non-skid floor is so far superior to the early flip tops that only hard core bling addicts ask for diamond plate these days. Likewise, there are no “fish hooks” to snag your clothes or worse yet, your fingers and the assembled body is much stronger in the newer trailers. On older flip top trailers, the inner wheel wells, the floor and the sides of the trailers started life as standalone pieces. Nowadays, fiberglass and gelcoat monocoupe “tubs” are fabricated in house complete with integral inner wheel wells and the floor sandwich previously described. Laminating Advantek to the bottom of the “tub” is the last step in this process. The sides of the tub still have to be laminated to the sides of the body, BUT these days mat is sandwiched between the sides of the tub and the sides of the body.