About to start building, please help before it's too late ;)

[oldtamiyaphile]

Well a little about me to start with.

I'm planning a round Australia trip to commence in mid January. I was planning on purchasing a VW camper for the trip, but the cost of a decent one, lack of A/C and reliability concerns made me think twice.

I always liked TD's and thought they'd make for a great project someday, so here I am. I will be towing with my TJ Wrangler which has A/C and minimal chance of breaking down or getting stuck

I'm looking at using a DIY bolt together 5X8 chassis similar to the NT one. My plan is to cut it down to a finished exterior wall width of 4'6", which will make it exactly the width of the Jeep body. I realize this may require the purchase of a new custom axle, which is OK as I may decide to go to a heavy duty axle later (after a few short break-in trips).

Wranglers have a very modest 1000lbs tow rating, so I want to build it as light as possible. I will be building with guidance of the generic Benroy plans, but haven't yet been able to decide on a profile....I may go Benroy as it's quick to build and I have a deadline.

First Q: Do we need all those cross members? Seems like basically all the trailer body weight is actually supported by the main rails. The A frame provides some triangulation and the floor helps out a bit too.

The 3/4" ply sides and floor seem like overkill to me. Is the 3/4" dimension a caravan industry standard that makes fitting of pre-fab doors and windows easier? I'm considering framed construction, but that might be beyond my time and tool set. Ideally I'd like to use preskinned caravan foam panels, but I'm unclear how these can be attached to the floor and roof beams, and I wonder about cost and if anyone will sell me a small enough quantity.

Do I need a spare tyre? If I look at my bike experience, it's always the rear that punctures, the rear tyres carry most of the weight on a bike. Front punctures are very rare. Now giving that I've never had a flat with a 4wd tyre, and only even had a slow leak in a road car (once), what are the chances of actually getting a flat when a tyre is only supporting 300lbs? Has anyone managed to get a flat? Will I notice before the tyre is shredded? I'm considering an on-board pressure monitor and a can of mouse as a light weight precaution. If the bolt pattern matches the Jeep I can possibly remove a mud guard and use that.

So far the weight of everything I want to carry is 200lbs (incl gas and water), add about 200 for the trailer, I 'm allowing about another 200lbs for the body, which should be achievable, but I'd like it much lighter than that. Who here has the lightest 4 or 5x8?

Now, onto my next saga, I've already decided on a light weight framed galley with 3mm ply skins. If budget allows I might even spring for some Dragon Plate carbon fibre skin. I work with aluminium so I could use that for framing.

The mattress I'm using is only 3' wide so that leaves me with about a 1' of space along side, which is where I want to park my mountain bike. I've determined that loading will have to be through the rear door, and it looks like it will have to be handle bars first (so the rear wheel sits back against the rear door). I will have a partition to keep me from getting greasy.

With rear loading a MTB, I can only have a 3/4 width galley, or have 1/4 of it removable. When I'm not camping the trailer will be used to transport a pair of road bikes, so I really want to go a bit modular here. Ideally the whole galley should be removable, but also a smaller removable section for solo camping with a bike. Any ideas on how to do this? I imagine the galley adds quite a lot of strength to the rear of the trailer, especially with the hatch open. How much bracing will I need to keep the rear all stable?

Thanks,

Bert

[PaulC]

I'm looking at using a DIY bolt together 5X8 chassis similar to the NT one. My plan is to cut it down to a finished exterior wall width of 4'6", which will make it exactly the width of the Jeep body. I realize this may require the purchase of a new custom axle, which is OK as I may decide to go to a heavy duty axle later (after a few short break-in trips).

Why go H/D if you plan on building a lightweight?


First Q: Do we need all those cross members? Seems like basically all the trailer body weight is actually supported by the main rails. The A frame provides some triangulation and the floor helps out a bit too.

If you're staying on the bitumen you could probably get away with a chassis and just bolt and brace everything to the floor. (It has been done)
I've built 3 now and dragged them to Israelite bay in WA, up the Birdsville, Strezlecki and Oodnadatta tracks. There is no way I would consider minimising my custom made chassis.


The 3/4" ply sides and floor seem like overkill to me. Is the 3/4" dimension a caravan industry standard that makes fitting of pre-fab doors and windows easier? I'm considering framed construction, but that might be beyond my time and tool set. Ideally I'd like to use preskinned caravan foam panels, but I'm unclear how these can be attached to the floor and roof beams, and I wonder about cost and if anyone will sell me a small enough quantity.

The specs are a guideline. If you only want to use 5mm and an internal frame go for it. Build it the way you want to.

Do I need a spare tyre? If I look at my bike experience, it's always the rear that punctures, the rear tyres carry most of the weight on a bike. Front punctures are very rare. Now giving that I've never had a flat with a 4wd tyre, and only even had a slow leak in a road car (once), what are the chances of actually getting a flat when a tyre is only supporting 300lbs? Has anyone managed to get a flat? Will I notice before the tyre is shredded? I'm considering an on-board pressure monitor and a can of mouse as a light weight precaution. If the bolt pattern matches the Jeep I can possibly remove a mud guard and use that

Been there done that, get a spare. It's cheaper, and easier, in the long run.

Bert, I won't quote anymore. We build a torsion box for our little vans. The galley gives it a lot of strength and minimises racking. Figure out a way of keeping the strength, maybe a top and bottom brace, but make sure the TD is stable. Getting up into the outback is a sure test for these little vans.

I'm in Adelaide, if I can be of assistance give me a call.
Cheers
Paul

[oldtamiyaphile]

Why go H/D if you plan on building a lightweight?

Thanks Paul,

My understanding is that a std axle might not survive our corrugated roads. Plus there's the question of brakes, my hope is to build light enough to avoid them, but the Jeep brakes are marginal with four people on board. I'm in WA so I'm actually planing on skipping the Plibara and NT for another time and if need be a modified trailer. I estimate the vast majority of the time I will be using roads or well graded tracks, I've been leaning towards building an on road trailer, and leaving it at camp. Any thoughts on that?

Part of why I like the bolt up trailer is it's quite easy to add, move, and remove parts if I don't like the way it works first time out.

[PaulC]

Why go H/D if you plan on building a lightweight?

Thanks Paul,

My understanding is that a std axle might not survive our corrugated roads. Plus there's the question of brakes, my hope is to build light enough to avoid them, but the Jeep brakes are marginal with four people on board. I'm in WA so I'm actually planing on skipping the Plibara and NT for another time and if need be a modified trailer. I estimate the vast majority of the time I will be using roads or well graded tracks, I've been leaning towards building an on road trailer, and leaving it at camp. Any thoughts on that?

Part of why I like the bolt up trailer is it's quite easy to add, move, and remove parts if I don't like the way it works first time out.

Okay, our road rules allow for an all up weight of 750kg before you need to fit brakes. You should be able to build a lightweight on road at about 300kg, or slightly less.
It's not the axle that fails but the bearings. You could fit a 35mm axle and use the Ford bearings, they're bigger, and you should be okay. You can still fit whatever wheels, they just machine the hubs to suit the bearings. Also, consider fitting shock absorbers if you think you might be spending some time on corrugated dirt roads.

I hope that helps, Bert.

Cheers
Paul

[Shadow Catcher]

If anything is marginal Brakes, tires etc. be assured Murphy will find you, (the corollary on Murphy is that he was an optimist). With our Tandem Bicycle I always carry at least two inner tubes and a patch kit (last time I had to use the patch kit).
As suggested else where, if you can use a hub with a bolt pattern the same as the Jeep you can use the same spare. We got stuck in Death Vally once and had to walk out (carrying five gallons of water in a back pack). We managed to catch a ride with a couple of prospectors.
ALWAYS plan for the worst that can happen, not for what hasn't happened yet!

[oldtamiyaphile]

Thanks, that is good info.

It will definitely be getting shocks, brakes pending road testing.

The chassis I'm about to order is here (the 5x8):

http://www.easytrailer.com.au/multifunc ... ilers.html

As a non folding design, it looks to be at least a step up from the popular HF trailer.

I came across some really nice alu chassis in my searches but the price

Still, I know what I'm going to build number 2 on:

http://www.aluminiumtrailers.com.au/ind ... &Itemid=77

I've resigned myself to building a second, because I need my trailer soon, at a modest cost. I'll explore all the material data sheets, CAD, CFD etc for the next one.

[Errol]

Hi oldtamiyaphile. I am building a 10 x 5 teardrop which I estimate will weigh in at around 450 kilos. The frame is 50 x 50 x 2 mm RHS with 15 mm flooring and 18 mm sides with cutouts to lighten it substantially. Ford bearings and stub axles fitted to a 50 x 50 x 3mm RHS main axle, again for lightness and of course, no brakes.
My frame is minimilist with strength coming from the under-floor storage compartments.
As for punctures, generally tyres will puncture more often in wet weather, and the rear tyres are usually punctured more often as nails etc will 'stand up' after the front wheels hit them, which is more evident on motorbikes. (Very rare for a motorbike to puncture a front tyre)
As Paul stated, carry a spare.
Overall, it sounds like your build will be challenging.
By the way, if you consider shockies, get some expert advice because if you fit a shockie with too short a spring travel, for example, the shockie will fail in a very short time. If you fit any shockie you find lying around, they will do the job, but just not for very long.
Springs with shackles and shockies will give better service for rough road use and slipper springs will give good service if set up properly. It all depends on budget and use.
In other words, go with what feels right for you and ask advice or opinions regularly. This is a bloody good site for that sort of thing.
All the best,
Errol (Western Queensland)

[Miriam C.]

to the playground.

If you look up in the menu above there is a tutorial. If taking a long trip here I would want the best foundation I could get. Now most of our roads are better here unless you hit a pot hole. Definitely get a spare

[Shadow Catcher]

Ours has an aluminum frame and it is the difference in weight that separates it from other smaller trailers.
The example you sent is way heavier than you need. Other sources for used or some one to make a frame for you would be some one making stock trailers or boat trailers. If you are a welder or know one competent to weld aluminum (TIG) then have one fabbed up. Ours is 25mm by 50mm box about 3mm thick. Had I designed one I might have gone with round. in either case the idea of using the tubing as a water tank intrigues me.
just dong a quick search came up with.
www.onesteel.com/products.asp?action=sh ... =Aluminium
Quick search Aluminum boat trailer builder in Australia.
www.mackaytrailers.com
If all you want is a frame I would expect they would be willing to leave off the boat handling stuff.

[oldtamiyaphile]

I didn't get too far with local alloy trailer builders.

It looks like I will be going with a DIY alloy chassis. Since I can get it at cost it will cost me less than steel. For jointing, I've decided to go with a bonded and riveted structire, saving me on welding costs too.

Compared to the NT style bolt up trailer I posted earlier, or the cost of a steel trailer welded locally, I'm basically getting an upgrade to a torsion axle and brakes at no cost Admittedly, I haven't allowed for wheels and tyres, mainly because they can be basically free up to big bucks for new tyres on alloy rims.

My only concern now is attaching the axle to the frame, six bolts into alloy doesn't fill me with confidence. Shadow Catcher, how does yours attach? Have you pulled it on washboard roads?

Re using the frame as a water tank, I can see some drainage issues there, having to tilt the trailer to get water out. You could design a rear V member that would be the lowest drainage point, but it seems like the capacity of a trailer is quite low (around a gallon).

I can certainly see using an alloy water tank as a cross member though. Indeed, I intend on using a water tank as a structural member in my design. I want to avoid having one custom fabricated, so we'll see about that one.

As far as my profile goes, I've started doing some airflow analysis, using a basic 2d CFD program. Instinctively and in isolation, one might think the pure the pure teardrop shapes are the most aerodynamic, but once you factor in the turbulent air coming from the tow vehicle, the best shapes seem to be the ones with a flat floor and no sweep up at the rear. A tongue box seems to help, and covering the A frame with sheet is a good idea too.

[PanelDeland]

Just as a suggestion consider using a bike rack mounted on top.It would free up space,keep the galley both larger and simpler to design and would keep the grease off of you.It might also lighten things up a bit since you wouldn't need an interior wall.

[oldtamiyaphile]

Yes, the bike senario is a major sticking point. It's an expensive bike so I'm reluctant to transport it thousands of miles on the outside. Because it has a magnesium fork I'm also reluctant to use a carrier that uses the front spindle as a mount, as most roof top carriers do. There's also the driving under a low branch in the bush senario

My internal floor dimension started out as 3'6", but measuring the bike read 3'7", so I was in trouble from the start. The handle bar is 25" wide, which is a fair chunk of the available width.

Possibly the most practial solution is to build 5' wide and add a hatch at the front. That handlebar remains a problem though

Edit: Now that I think about it, the handlebar is held by just two bolts, I can deal with removing it. Sometimes it helps to just talk things through.

[sjacobso76]

I'm also a mountain biker building a mount into my TD for my bike. I was reading through wondering if the idea of moving the handlebars would come up. Removing them seems like a no-go, as you would have to remove your break levers and shifters to get it the bars totally off, but you can just rotate it to be in a straight line with the bike frame. That adds some length, but shouldn't be a problem if you're leaving on the wheel as you're already that long anyway.

If you just use that plan, couldn't you just make the door tall enough and feed it through there? Seems a lot easier than building a hatch to feed it through.

[kennyrayandersen]

And why is it again that you can’t just put a receiver on the back and mount a good standard bike rack (which doesn’t use the fork to attach)? You can tie them down well, make provisions for locking etc. It sounds a lot easier than taking the handlebars off, which sounds like a PITA. Of course I will admit that most bike racks aren’t really designed for MTBs, but rather road bikes. Still, I always managed to get is secured somehow. Since you a fabbing so much, it might not be too tough to come up with an external rack.

[Shadow Catcher]

I built a rack to hold our tandem MTB on the tongue horizontally (wide trailer and this lets me keep an eye on it). I have also built vertical racks that will hold 1 or five bikes, made of aluminum conduit. The vertical,2"ID, is split in half and with the top half off accommodates a single. this could be accomplished with high strength thin wall steel conduit.
There are couplers that attach to gear shift and brake cables that preserve adjustments/indexing when handle bars are removed but in your case it sounds like you would only need to rotate them 90 degrees.