Off road trailer from thought to trail in 90 hrs

[browningbuck]

I started a trailer build for this spring, summer, and falls camping back on march of this year. with in 90 man hours we were out camping in it. Now she isnt 100% done, but close enough that it got safety inspected, title, and licensed and had a bed

So heres the pics of the build.

this was to be a complete build from scratch






My helper lays a pretty good bead of aluminum







working on the tail lights



used diesel locomotive wire which is pretty cool stuff if you ever look into it



the bottom of the trailer is 100% perimeter welded so that i could water proof and insulate the floor with 3" of R31






getting the .05" aluminum over the insulation and welding it down took a LOT of effort and was a PITA!


decided i would try the timberen axles.... next build i will not choose them. they are amazing for the road however out in the dirt on wash boards an air bag system with shock would out perform by a long shot












at this point she weighed 800 pounds! watch out for that clearance


PAINTED to match the jeep


the bed ended up at 60"X85" im kinda tall


star gazing window



the view from the door isnt bad. shes been on two trips in two weeks for a total of ~1000 miles

[browningbuck]

now i will say, i built this fairly quickly to find what i liked in a trailer and what i didnt. I anticipated selling this one at the end of the year once ive used it and found what i felt like i needed to improve. This is part of the reason i rushed through it, also i just wanted to get out. That being said, i took a lot of time setting up my structural welds and geometry. I spent most of the time insuring those aspects were perfect but the finish aspect i knew id be pulling it through brush and trails so i didnt care about oil canning of the aluminum which had been full perimeter welded (which i dont recommend and wont do on the next one!). That being said, the next one will have similar design, the wheels will be pulled in to give it a thinner stance (just inside the jeep stance , currently its 4" each side out side), the insulated walls and floors are a must (we did a night at the north rim that hit 28*F and we were comfortable with just blankets), Ill shorten up the tongue a bit (it was left long so that a privacy tent could be installed on top of the tongue and be used as a changing/ restroom. however i just dont see us using it even though i thought it was the best idea i had that i havent seen done. ill try and get a pic of it set up). Anyway those are my current thoughts, let me know if you have any questions.

[KCStudly]

Cool build.

[S. Heisley]

Building something like this in 90 hours is impressive. All your pictures were fun to view. Thanks for sharing.

[Shadow Catcher]

I will second Sharon, Impressive.

[AlgoDan]

Looking good and enjoy the off-road.

[browningbuck]

thanks for all the replies glad you guys like it. Im happy to be almost done with this and to have learned what i want in a final design! i will say that with a jeep as the tow rig i average 16MPG with the 1000lb trailer and another 200~lbs of gear. most of the weight on the build was in the wheels tires and axles (total of those was ~330lbs). next one i think i can get away with about 800-900lbs the sheet adds a lot of shear strength to the system (a lot more than i calculated for).

[Woodbutcher]

Nice job!!! I wish I could weld

[rebapuck]

Nice build.
It made me wonder if a metal(even insulated) trailer is hotter/colder than a wooden one. Cars sitting in the sun get unbearable in the summer.

[browningbuck]

rebapuck,
good thought. So far i havent made the reflective cover for the star window (this lets the majority of the heat in). However being its all aluminum i am able to open the door let ambient temp in and change the over all temp of the trailer in 10- 15 min. i was surprised at how quick the insulation let go of the heat (being it was the largest chunck of mass i thought it would have taken longer). Also as you can see in the pictures i havent peeled the protective film off the inside of the trailer walls was keeping that on until i got the cabinets installed today/ next week? after that the walls should also help be reflective of temp rather than grabbing it.

[alaska teardrop]

Buck,

I also have an interest in building light weight trailers using aluminum. You sort of asked for a critique for your next build. So, some suggestions.

Tongue: I assume that the tongue rails are 3" sq. tubing, but what is the thickness? Did you do any tongue strength calculations, especially considering that aluminum cycles fewer times than steel before stress failure? Also, when welding the tongue tubes to the front cross member,welding parallel to the tongue tubes on the underside of the cross member is fine, but welding across the top of the tongue tubes in front of or behind the cross member sets up the potential for fatigue cracking & failure of the tongue. Especially aluminum.

Insulation: I'd recommend using extruded polystyrene next time. It doesn't absorb moisture, it can be made to fit without air gaps & it has a higher R-value than fiberglass bat. By compressing the R-30 bat into 3", you may have increased the R-value per inch slightly, but decreased the total R-value considerably. Probably down from 30 to about 10 total in the floor.

Floor: IMO, the current design has so much thermal bridging from the underside panels, through the chassis tubing & to the aluminum floor that the overall R-value of the floor is almost nothing. When the trailer is heated in cold weather it's a huge attraction for moisture. The same goes for the interior walls & ceiling.

Timbren axles: What is the load rating of your axles? I've found that a suspension rated slightly more than the gross weight rides & handles best on rough roads & trails. For instance, a 1000# trailer on a 2000# axle of any kind is going to take a beating on rough roads. Also, how did you attach the axles? Did you weld in a steel cross tube? Seems like a place to take special care in design in order to avoid failure.

Having some past experience welding aluminum boats with a spool gun, I can understand your disappointment in trying to weld .050" (especially to a thicker material). I've found that 1/8" is about the minimum thickness to successfully weld aluminum with a spool gun. As an alterative, consider using VHB tape & structural rivets for attaching the sheet aluminum.

Here is my example of how I've built with aluminum & extruded polystyrene that might give you some ideas on the next build: viewtopic.php?f=27&t=51991

Happy trails, Fred

[browningbuck]

alaska, thank you for the reply. The entire lower frame is 3" tube .25" wall thickness. im confident in the strength of this wall thickness, However im a little unclear what you were stating about the welds? the tongue is welded both perp and parallel to the cross members.

The thermal bridging on the floor was something i couldnt really avoid with what i was doing on the frame. The extruded poly is the first thing on the list of revisions for the reasons you stated plus the ease of installation vs batt.
as for thermal bridging in the walls and ceilings. I think i off set the exterior vs the interior studs fairly well allowing the greatest separation. ill take tips on how to better do that though. i saw you used wood interior which im not a fan of wood but i can see how that helps on minimization of condensation.

the axles are the 2000# offroad axles. Like i stated they work great on road conditions however on choppy or washboard dirt roads the rubber compression/ rebound arent cutting it imo and will do a airbag with shock next time. mounting of these axles was done via a buttressed angle on the back side of the axle sandwiching the frame with the grade 8 1/2" bolts through it all.

after doing the .050" panels with a gun i know hat VHB is a no brainer now

for other items i plan on pulling in the wheels into 77" which will loose the fenders so will have to install a side table, shortening the tongue about 14", extruded insulation, vhb taping panels, tapering the front of the trailer to follow the angle of the tongue giving more room in the interior, A members on the tongue beam at each frame connection,minimized frame design,light diamond plating at the front of the nose,low venting, thicker bed foam (4" currently),add leveling bubbles and possibly leveling system,small door between galley and main, look into better windows, airbag shock suspension, lighter aluminum through the internal framing, better interior framing lay out(match insulation layout), have the 3" frame tube face the rear on each side to act as receivers for a rear rack, install a water tank in the demising wall, and im sure a few other small things im not thinking of at the moment.

[alaska teardrop]

alaska, thank you for the reply. The entire lower frame is 3" tube .25" wall thickness. im confident in the strength of this wall thickness, However im a little unclear what you were stating about the welds? the tongue is welded both perp and parallel to the cross members.

Although we don't have tongue strength guidelines for aluminum, as we do with steel, three 3"x1/4" sq. tongue rails seem adequate to me also. The shorter tongue on the next build will also be an improvement in vertical tongue strength. Maybe one of our resident physicists can explain better than I about the welds. But anyway, as you tow, even paved road, the weight of the cabin is continuously changing at the point where the tongue rails meet the front cross member. Because of this the tongue rails flex (cycles) vertically a given number of times before the molecular structure becomes brittle & cracks (usually alongside the weld). Aluminum much sooner than steel. Not all, but a good portion of the vertical strength of your 3" sq. tongue tubes are in the top & underside portion of the tube. Welding (heating) across the tongue rails changes the molecular structure of the metal at the most critical point.

he thermal bridging on the floor was something i couldnt really avoid with what i was doing on the frame. The extruded poly is the first thing on the list of revisions for the reasons you stated plus the ease of installation vs batt.
as for thermal bridging in the walls and ceilings. I think i off set the exterior vs the interior studs fairly well allowing the greatest separation. ill take tips on how to better do that though. i saw you used wood interior which im not a fan of wood but i can see how that helps on minimization of condensation.

It's almost impossible to avoid thermal bridging in the walls, because of door & window framing, exterior & interior mounting framing. But the floor & ceiling insulation (IMO) are both the most important considerations in cold or hot weather. Suggestion for the floor: If you require the underbelly pan, fill the chassis frame voids with 3" of extruded, add a full sheet of 1" or more of extruded & lay vinyl or manufactured flooring on top. Skip the aluminum floor. This method also isolates & creates a thermal barrier for the perimeter chassis framing. Also, consider insetting the cross ribs for the front, roof & rear so that you can sheath the ribs, eliminate the bridging & isolate the corner & roof framing as I did on the N.L.

the axles are the 2000# offroad axles. Like i stated they work great on road conditions however on choppy or washboard dirt roads the rubber compression/ rebound arent cutting it imo and will do a airbag with shock next time. mounting of these axles was done via a buttressed angle on the back side of the axle sandwiching the frame with the grade 8 1/2" bolts through it all.

Ya, 2000# is just too much for a 1000# trailer (IMO). I think I've read that Timbren will derate the units. On your current build consider adding the optional steel cross tube. I should think that it would help distribute off center or side loads in the back country, avoiding possible twisting of the frame where the axles mount.

after doing the .050" panels with a gun i know hat VHB is a no brainer now

for other items i plan on pulling in the wheels 8" , shortening the tongue about 14", extruded insulation, vhb taping panels, tapering the front of the trailer to follow the angle of the tongue giving more room in the interior, light diamond plating at the front of the nose, airbag shock suspension, lighter aluminum through the internal framing, better interior framing lay out(match insulation layout), and im sure a few other small things im not thinking of at the moment.

Sounds like you're learning as fast as you build. That's great.

Keep up the good work, Fred

P.S. Almost forgot & you may already be aware, but with only 500# on each trailer tire, you can run way less tire pressure than on the Jeep for a smoother ride.

[browningbuck]

Alaska, i see what you are stating about the tongue, i did consider this originally and was why i went with the two angled members to minimize the flex at that first weld. I dont have calcs to see if they will work, but i will keep my eye on it to see if signs of failure start to show.

the bridging is something i will really have to think about and see what i want to do. there is a possibility of using a synthetic floor(would require more supports here which may be counter productive), wall, and ceiling material on the next build. this would help tremendously on the interior however there is still a possibility of condensation depending on what the psychrometric chart would be like in the trailer at any given point.

I feel the axles are properly sized, the trailer is 1000 but when i load up im adding up about 1600 i bet? i havent weighed yet once loaded, usually in to big a hurry to get some where. however the tire pressure still may be a valid suggestion.

thanks for the suggestions and thoughts, makes me egar to get enlightened mark2 going.

[alaska teardrop]

Alaska, i see what you are stating about the tongue, i did consider this originally and was why i went with the two angled members to minimize the flex at that first weld. I dont have calcs to see if they will work, but i will keep my eye on it to see if signs of failure start to show.

the bridging is something i will really have to think about and see what i want to do. there is a possibility of using a synthetic floor(would require more supports here which may be counter productive), wall, and ceiling material on the next build. this would help tremendously on the interior however there is still a possibility of condensation depending on what the psychrometric chart would be like in the trailer at any given point.

Extruded PS is commonly used as an underlayment for flooring (even cement). When you finish the interior on this build, you could lay in a full sheet of insulation on top of the aluminum & then the flooring. I wouldn't worry about support - you could support a dance troop on what you have already!

I feel the axles are properly sized, the trailer is 1000 but when i load up im adding up about 1600 i bet? i havent weighed yet once loaded, usually in to big a hurry to get some where.

I agree. Sorry, I misunderstood, thinking the gross would be 1000#.

however the tire pressure still may be a valid suggestion.

A good way of determining the proper tire pressure for the load is to find the 'load index' number on the side of the tire & use a pressure/load chart that applies to your tire.

Sample chart:

thanks for the suggestions and thoughts, makes me egar to get enlightened mark2 going.