Originally Posted by Retusps
I have no problems crawling around under any vehicle, but with inclosed uderbellies just what would I be looking for in a well built frame ete.
On some ultralites, you will find an I-beam that is made from 3 pieces of mild sheet steel welded together to "look" like an I-beam. Just run your finger along the weld seam between the bottom flange and vertical web to spot them. I've seen these on 5-6 makes/models now. These have much higher flex in them than a forged I-beam or the less common BAL/Norco Ultraframe. It's my option that it's best to avoid the fabricated I-beams as they can cause all sorts of problems down the road. Talking from firsthand knowledge... After a while, you'll learn that some frames are just built better than others. It's the TT manufacturer that provides the specs to the frame manufacturer (eg., Lippert) and not the other way around, so you will find some better Lippert frames than others on different brands.
Frames can cause problems and can eventually suffer cracks and failed welds. Not trying to be alarmist, but the more you learn ahead of time, the better. Just do some internet or forum searches.
If you want to learn about better frames, look into Outdoors RV units who make their own HD frame or Lance who use a BAL/Norco frame.
Some frames have a length of 2x2 square tubing welded to the bottom of the I-beam where the spring hangers are. The greatly strengthens the beam. Some frames have what's called a gusset at the spring hangers. The is a piece of steel welded at about a 45 deg. angle from the outside of the bottom flange up onto the side of the beam. Also greatly increase strength. Some TTs have a 6" tall spring hanger while some have a 4" tall one. The taller ones create more leverage action side to side. I've seen the bottom flanges of an I-beam distorted from all the side to side flex where the is just the spring hangers welded to the I-beam. Eventually, there would be a serious failure.
You're right, an enclosed underbelly doesn't let you see what's in there. Problems can happen with the cross bracing, tank straps, spacing of bracing, the weld quality, etc. Some find the floors to be somewhat soft and it can be because the cross-bracing/joists are too far apart.
Sometimes you'll find welds only partially done and/or not good quality. The proper way to do welds is for the entire joint to be welded, but often it's only partially done. You can try and see how the A-frame is attached and welded to the main I-beam/platform.
Check axle ratings versus the GVWR minus tongue weight. Sometimes, axle ratings are too close to the weight they carry, and a few have found them under-sized. You can also look at tire capacity. If available as an option, you might want to consider upgrading from load range C to D.
Some manufacturers are providing Ultru-Lube and EZ-Lube axles. It's my opinion they're not what they're cracked up to be. Some think they're great. Some trailers will have self-adjusting brakes. I think that's good. Equalizers can be a weak point. If you have the option, Dexter EZ-Flex equalizers are very good, heavy duty and have wet bolts for greasing. The standard plastic bushings are a real weak point and don't last. Ours were totally shot from new, due to the mileage from plant to dealer.
Shock absorbers would be a good idea, and really ought to be a standard item. They're rarely standard on TTs and sometimes are an option. Can be added but is harder on some units than others.
I'd also take a close look at dry weight compared to the GVWR. Sometimes, when you are fully loaded for camping, your actual weight can be close to the GVWR. They may indicate you have a high cargo carrying capacity, but it can be a lot less in reality. On average, you'll add 1,000 - 1,500 lbs to a TT when loaded up for camping. Full tanks of liquid would be on top of this at just over 8 lbs/gal.
Also, when shopping and weight is a concern, don't go by the published factory trailer or tongue weight. It always goes up and some more than others. The safest thing to do is use the GVWR. Our current TT is only 200 lbs away from the GVWR with just ordinary stuff loaded into it and for a short trip. It's also good to weigh your TT at a scale when you first get it. Even better, take it to a scale as soon as you get it before you load it up with anything and do any mods to it so you have a base weight for reference. Sometimes all the factory options you order can add a lot of weight.
An RV show is a really good way to see a lot of different units. At the last show here, I was easy to spot as I was the one crawling under units. A couple of salesmen were wondering what the heck I was doing but I learned a lot.