Building 5x10 Tear on a 4x8 HF Frame

[pgutting05]

Hey there everyone! I have been browsing the forum for about a year now getting everything together for my build. Initially I was going to build a 4x8, but after some consideration and evaluating my current and future needs, I have decided to build a 5x10. Unfortunately, I already purchased a 4x8 HF trailer. I have already bolted (and welded) the frame together as well as bolting and welding on a 2' extension off the rear. I have also extended the tongue 24". Before I get too much further into this I want to make sure I am going the right direction with this. I also want the tires and fenders to sit outside the plane of the walls, so i will probably be going with a Flexiride axle. I am thinking that in order to build out to my desired 5' width, I should frame the floor up with 2x4's that I will cut down to 2.75" to keep the weight down while still maintaining the needed rigidity and then use a 3/4" birch plywood for the floor (which I have also already purchased. Do you see any issues with this idea, or should I just scrap my 4x8 and build a 5x10?

Some other notes about the trailer. I will have 21 gallons of fresh water, a propane instant hot water heater, 100 watt solar panel on the roof as well as an 800 watt generator on the tongue in front of a deck box that will house the battery and solar charging unit. I also have an automated power distribution unit (although I cannot think of the brand or model at the moment). The exterior wall sheet will be 1/2" birch ply with 3/4" internal framing and 1/4" birch interior sheet. Walls and floors will be fully insulated with foil backed foam. Exterior walls and roof will be sheeted with .040 aluminum. I am going to be setting this trailer on 15" wheels and tires for some off road capability. No crawling or anything. I camp up on the north side of Yellowstone and Glacier National Park and would like to be able to drag the trailer along some of those bumpy roads.

With that info, what would your suggestions be for widening this trailer, Or should I just go with my idea of using the 2.75" floor framing; being that it will all only be overhanging by 6" on either side? I have searched all over the forum and cant quite find what im looking for (although I'm sure I'm not looking the right way since there seems to be an answer to everything on here)!

Any info you guys can give me would be greatly appreciated.

Thanks,

Peter

[Corwin C]

Overhanging the trailer frame by the floor really isn't that big of a deal. Many here have gone much farther than 6". You should be fine. It sounds like you've got quite the project started. Best of luck.

[len19070]

If you take it to 64" you won't have to mess around with "Half Fenders.

An Over the wheel build.







Happy Trails

Len

[pgutting05]

Thanks for the feedback guys. I appreciate it. Now, time to get this thing done!

[KCStudly]

Welcome.

1/2 inch outer and 1/4 inner wall panels are excessive, IMO.

Many people who start with 1/4 outer and 1/8 inner say that they should have used 1/8 on both in and out, especially if they use alum skin.

5mm (3/16 inch) is a good compromise IMO.

Many have done 5 wide using 3/4 deck and no subframing (Bob Henry to name one). Just be sure to use cleats (2x2 would be great) along the edges of the deck so that you get a nice solid screwed and glued connection. The front wall and bulkhead are very rigid and tie the walls back to the chassis, so as long as the box is sturdy it will hold the floor up just fine.

You added 2 ft to the rear? did you move the axle back? Have you looked at your weight balance yet?

I wouldn't bother changing axles just to put the wheels outside. Leave the wheels under or use half fenders, but keep the track narrow for maneuverability. Just don't build so high that your CG gets tippy in the wind. 5 wide on 4ft trailer 4 ft high should be plenty stable enough.

I know it is an old saw, but, think "airplane", not "tank". If you want to survive two track service and forest roads, my way of thinking is to build a soft riding, but durable suspension (Jeep YJ rear leaf springs, rugged 4x4 hanger parts, and shock absorbers with bump stops), then build the box strong and tight, but light weight. The heavier the box is the stronger everything else needs to be to survive. The box is strong by its nature, so if you can build it light everything else will have an easier time surviving. Leaves more capacity for hauling gear and supplies that way, too.

[pgutting05]

Welcome.

1/2 inch outer and 1/4 inner wall panels are excessive, IMO.

Many people who start with 1/4 outer and 1/8 inner say that they should have used 1/8 on both in and out, especially if they use alum skin.

5mm (3/16 inch) is a good compromise IMO.

Many have done 5 wide using 3/4 deck and no subframing (Bob Henry to name one). Just be sure to use cleats (2x2 would be great) along the edges of the deck so that you get a nice solid screwed and glued connection. The front wall and bulkhead are very rigid and tie the walls back to the chassis, so as long as the box is sturdy it will hold the floor up just fine.

You added 2 ft to the rear? did you move the axle back? Have you looked at your weight balance yet?

I wouldn't bother changing axles just to put the wheels outside. Leave the wheels under or use half fenders, but keep the track narrow for maneuverability. Just don't build so high that your CG gets tippy in the wind. 5 wide on 4ft trailer 4 ft high should be plenty stable enough.

I know it is an old saw, but, think "airplane", not "tank". If you want to survive two track service and forest roads, my way of thinking is to build a soft riding, but durable suspension (Jeep YJ rear leaf springs, rugged 4x4 hanger parts, and shock absorbers with bump stops), then build the box strong and tight, but light weight. The heavier the box is the stronger everything else needs to be to survive. The box is strong by its nature, so if you can build it light everything else will have an easier time surviving. Leaves more capacity for hauling gear and supplies that way, too.

I had initially thought about using 1/4" for the outer wall, but called around to some manufactures and most recommended 1/2" outer with 1/4" inner skins. I am concerned that if I don't use any sort of bracing under the floor it will want to sag over time at the edges? Not really sure there lol. I would generally just take the wood back and exchange it, but the nearest lumber yard to me that I purchased the ply from is about 75 miles round trip. I was a little concerned about the impact resistence of 1/4" vs the 1/2" ply. With all the freaking rocks and crap in the road up here in WA, I have cracked 5 windshield in 5 years, not to mention all the dents in the front of my vehicles. It's like they plant little rock landmines in the roads up here .

I have not yet mounted the axle as I am trying to find something I like before I commit. The more I think about it, the more I just want to go the Jeep suspension route. The tow vehicle is going to be my Jeep XJ, so that would work nicely. Not to mention, I could build a nice suspension system using Jeep parts for pretty cheap. Right now, I am a little confused about exactly which axle length to use. The plan is to do some serious searching tonight to get all the numbers figured out. I am really trying to get this done for some summer camping this year, but am definitely NOT going to rush things to get it done.

As far as half fenders go, I have been debating that as well. I don't think I will be doing much in the way of narrow trails, but you just never know in the future. I really like to look of the fenders out past the plane of the wall, but as you mentioned, there could be some issues with maneuverability. I guess I need to ponder this one for a while. I guess I could just build this one without half fenders and another for when I plan on going up some narrow trailes. Heck, it's just time and money, right?

[KCStudly]

Your HF 4x8 didn't come with an axle already? Why not use that one?

You can certainly do a full width axle on 5 wide. TPCE is 64 inches out-to-out and my Dexter axle is 72 inches hub-to-hub. I like the fenders outside of the walls, too, but it does not match the track width of my Jeep, making the trailer much wider at the fenders. If you already have the HF axle those are good enough reasons to do the half fenders and have "the look" of extended fenders without the hassle and expense of changing everything. I guess it just comes down to your priorities... part time camper, speedy budget builder or serious boondocker, money and time are no objects... there's a full spectrum of samples here to compare to. I did the Jeep suspension on TPCE because I am going deep "out there" in the mountains on a sometimes rough forest service road, and metal fabrication is in my background. Don't underestimate the difference in cost, either. My suspension was an E-ticket item ($$$) on my frame build (wheels & tires, then brakes and suspension). Standard trailer stuff is much more thrifty.

If the front wall and bulkhead wall are located over xmbrs on the steel trailer frame, those walls will act like super rigid beams supporting the side walls. The side walls are super deep beams spanning between these two supports (assuming everything is glued and screwed well and remains water tight... no rot, and that you leave a few inches under the door intact so the wall maintains its integrity). The field of the floor will be supported by the trailer frame as well. That very short span of 6 inches between the wall and the trailer frame is less than the spaces between xmbrs in the field of the frame, so there should be no worry about sag. It's not like you will be standing or laying there. The walls hold the floor up, not the other way around. Make sure that you screw into solid cleats (not the edges of the ply) and you will be dandy!

The reason I have my walls sitting on top of the frame rails is to protect against bottoming out on rocks and stuff. The walls will stiffen the frame, not the other way around.

You can clad the lower front with some thin alum diamond plate to protect from rock chips and dings (I plan to do this, too).

If you feel you must make a subframe out of wood, think 1x2's on edge, or even 1x4's flat or on edge, not bigger (unless you are trying to space the floor above the fenders, in which case you should seriously be looking at under floor storage. Check out Zach's XII. IMO his floor is still over built, but done very well. He does bomb down forest roads, and he builds convertibles (in engineering terms, no rigid roof membrane/diaphragm), so I guess he felt he needed the extra strength in the floor. For a hard top I would still consider 1x on edge instead of 2x.

These are just opinions that I have formed from reading a ton of info here and paying attention to what people who have done it have learned for themselves. I can't ever recall someone saying that they wished they had built heavier (except for maybe weak single tongue tube failures), but there are many, many examples of people saying that they coulda, shoulda built lighter, and will do so on "the next one".

I'm sorry if I am not helping you make any decisions. It is hard with all of the options and choices to make. Keep planning. You will build what your senses tell you is right for you (TLAR) and it will work out great!

[davidniebeling]

Hey Peter, I am certianly no expert, so this is ONLY my opinion. I am on my second TTT and I used 3/4" furnature grade ply on my first trailer (4'x8' HF frame) and it was overkill. For the trailer I am in the process of building I am using 1/2" Baltic Birch with 2x2 interior frames and I am going to use 1.5" rigid foam and 1/4" pine T&G paneling on the interior. Is it overkill? Maybe. Do I care? Not really. You see, I travel those same mountains as you, just on the other side of the hill! I never had a worry with the first camper and I'm sure I won't have a problem with this one. The camper I am building is 6' wide by 10' long and about 5' high. I built a 1' frame all the way around my HF 1700lb 4x8 frame and so far it seems quite rigid. I purchased 2- 6'x1" angle iron to mount under the frame just to be safe but so far I have not mounted them because I'm not sure I need to. I probably will later, just 'cus. If you want to check out my build video you can check it out at http://www.youtube.com/watch?v=ytFFIHmY-cI

[davidniebeling]

Sorry, this is the one with the 1 ft extension I built. Hope this helps. http://www.youtube.com/watch?v=lT8JGdkkfAU

[wingloader]

Folks, would you use drywall screws to assemble your various wooden parts of your trailer? I use them for pretty much everthing and they are pretty awesome fasteners.

[KCStudly]

Folks, would you use drywall screws to assemble your various wooden parts of your trailer?

No. I only use them for fixturing (tooling like router templates and temporary blocks for gluing).

They are brittle and the heads can snap off.

[Corwin C]

Folks, would you use drywall screws to assemble your various wooden parts of your trailer? I use them for pretty much everthing and they are pretty awesome fasteners.

I do use drywall screws for assembly to hold the parts while adhesive dries. The adhesive/glue is where the strength is. As KC says, they are brittle and will snap off, so don't rely upon them for strength. Removing the screws when everything is dry is optional.

[pgutting05]

Thanks for all the good info, guys. I am really starting to narrow things down in a hurry now. I have decided to go with a standard axle with leaf springs and electric brakes. However, I am having a hard time figuring out how much width the brakes will add to the axle. I don't want to end up with 3" between my tires and the trailer wall. Is there a thread anyone would recommend I read through?

[Corwin C]

In most cases, the brake drums will replace the hubs and shouldn't change the width much if any at all. If you have slip on drums, the width will only change by the thickness of the drum where the lugs go through ... I would imagine at most 1/4" on each side. If you're ordering the axle with brakes, the manufacturer will have already taken this into account.