Thread: Box/camper trailer build

Wow, it's been a while since I started thinking about this project...

In the mean time, The wife and I've had another baby, I've gone back to uni for a career change and made a start on the trailer in preparation for a trip with the family up to Darwin and across the top before winding down the east side starting in late May this year. I'd better get a wriggle on.

Because money is a bit tight at the moment and I couldn't justify the $700 to get the chassis galvanised, I used gal RHS (minimal price increase over primed) and have painted the welds with cold gal zinc paint. Draw bar and chassis are 75x50x3 with 50x50x3 bracing. I asked for 50x50x2, but didn't realise they stuffed it up after it was cut and I'd paid for it. Still, the weight increase is only 7 kg, so I'm not going to cry about the extra strength. Floor is 2 mm gal flat plate. I bent the sides, guards and gate panels from 1.6 mm gal.



In between my previous trailer thread and this one, I decided I didn't have time to develop and test an automotive spring solution before my trip, so I went 'off the shelf' with springs. The 1.35 t springs I'm using are by a large manufacturer of trailer parts who I wont bother naming. I'm sure the springs will do the job, but they scream “made cheap” rather than “made well”. They retail at around $350, which I think is way too high for the build quality, or lack thereof. When I was still playing with the idea of automotive springs, I was quoted the same money for a pair of locally made variable-rate leaf springs from a Landcruiser. The build quality of these would have been far better than the trailer springs I bought for the same money.


After speaking to a suspension engineer at a shocker manufacturer (parts suppliers and suspension places had no idea, so it was great to have a conversation with an expert), I picked up a pair of Pajero front shocks that are short enough, have 4wd build strength and as per the engineers advice, minimal compression and comparatively high rebound valving. I'm hoping to find the time to run some comparative testing with an accelerometer (iphone, wiimote, etc.) fixed to the trailer - with and without load, with and without shocks and perhaps even the removal of spring leaves to find what gives the best ride.


I haven't bought one yet, but I'll be using a Tekonsha P3 controller that can be fleabayed for $150 delivered.


Axle is 45 mm solid (1.4 t) with electric brakes. The tow vehicle is a conformadore, so the stud pattern matches and I have commercial tyres of the same diameter as the car so I can raid trailer wheels for the car in an emergency.


The four RHS posts at either end of the sides have open ends so I can slot the legs of a cage on and off easily when the camper top isn't on.


With a ball height of 360mm, I expect the front of the tray to be 140 mm lower than the back if I mount the coupling on the top of the draw bar, so I'll put the coupling plate on the bottom which will make the front only 70 mm lower. I can always mount the coupling on top to suit a different vehicle with a higher tow bar later, if I need to.

While a common (and good) suggestion is to weld the drawbar to the front spring hangers, it's a bit difficult in this case with the triangular shape. Anyone think it's overly critical, or should I just leave the draw bar with square ends and weld it to the chassis on either side as shown in the second picture?

Mick

Nice start Mick, and Congrat's on the addition to the family!!

Not hugely critical to tie the drawbar to the front hanger, particularly if it's not going off road.
However, you could add a piece of flat steel shaped to fit...
Attachment 163260

Thanks, mate.

At the moment, I wont be doing any big off road stuff, but I certainly don't want to rule out the possibility in the future. Within reason, I want this thing to be pretty much unbreakable, so I will tie the draw bar in. I'll just shape and bend the square end today as you've drawn it and post the results.

I got a bit of time to melt some rods on the weekend and the chassis in now rolling. No photos of it on wheels yet, though.

Here are a couple of photos of the coupling mock-up. The vertical bit of 75x50 is just there as a spacer and will be replaced with about 300 of 75x75x3. I run a 75x75 socket just behind the coupling of my current 6x4 trailer that I plug the 65x65 shaft of a 'T' piece into. This allows me to carry 5.4 or even 6.0 length across the top of my cage with zero rear overhang - well, maybe a 100 or so off the end to tie the rear down. The string line pulled out of the way in the photos was to line up the apex of the draw bar with front- and rear-rail centre lines.

I cut the coupling plate from some scrap 6 mm black plate. Grinding off the oxide so that paint would actually stick longer than a couple of weeks was a pain, but the rusty, peeling paint look of most commercially built trailers definitely does not appeal.

The central 50x50 is a bit of a multi-purpose addition. It directly ties the rear rail of the chassis to the coupling (via the central bracing rib under the floor) and also provides a potential spare wheel or toolbox mount if I decide to add such to the drawbar - I like the idea of where possible, avoiding welds on the actual drawbar near to, or forward of the front rail to minimise stress fractures. I'll also fix the handbrake handle to the central spar just behind the coupling.

Yonnee inspired me, so also shown is the drawbar rear end about to be welded to the frame and to the front spring hanger.

I might take a mate up on his offer of the use of a mig to stitch the floor, sides and guards on. Attaching 1.6mm gal to 2.5 mm gal angle for the gates was do-able with stick, but the results were not the prettiest.

Love to hear some more suggestions.

Mick

Well, everything in the previous photos is now welded, but I'm a bit time-poor at the moment so progress is a bit slow.

Upper and lower shocker mounts are fabricated and in place. Uppers made from some off-cuts of 100x100x3 while the lowers are high tensile bolts welded to the rear edge of the fish plates.

I had made (and mounted) front an rear gates from 1.6 mm gal sheet with a double fold at the top and 40x40x2 angle for the sides and bottom, but decided that it just wasn't robust enough. They have now been re-made with a full 40x40x2 RHS frame filled in with 1.6 sheet.

Anyone got any suggestions on where I could get five-core tinned copper wire from in the northern suburbs? I'm a bit over the corrosion problems that always seem to strike bare copper trailer wiring after a couple of years.

Is your top shock mount strong enough?
It looks like you have some sort of bracing visible on the left hand side, but if the mount is just 3mm rhs, you might find it bending after a few big hits, or the pin chewing out the hole over time.

Also it might be worth plating between the mount and the chassis rail, I've seen shock mounts pushed through 3mm chassis rail walls

Last year I rebuilt an old camper and did a similar trip to you, with 4 young children. It was an amazing experience for us all, so glad we did it!

Thanks for your feedback, festy.
I'm not too worried about the mounts damaging the chassis or peeling off, as the two sides run the full depth of the rail (see attached diagram). What does concern me about the current configuration is the plate that the shocker pin bolts to. I agree that the hole may tear through the 3mm plate as it is.
The photo shows how I will probably weld a bit of 3mm angle to the top of the mount to brace things a bit better.

I found 5 core tinned copper marine trailer wire at All About 12 Volt in Somerton. They stock 7 core as well. Unbelievably, at $2.10 / m it was less than half the price of normal copper wire from the usual auto stores. Nice to have a win occasionally. 6mm twin core to run brakes and power to the trailer battery was only $4 /m, too.

Had the usual fun and games dealing with VicRoads. Bloke on the phone said that to book an inspection (I need one as the trailer will be registered with ATM > 750 kg), I need to "get a VIN number issued". I was going to ask him if he thought I should use my PIN number to get some cash out of an ATM machine and buy some LPG gas on my way to VR to pay the inspection fee, but figured he probably wouldn't have got the joke...
Anyway, the advice was that I would have to take the manufacturers plate into VicRoads in person to be issued a VIN. "Sounds like a crock", I think to myself, but head off anyway - not bothering to dig out the manufacturers plate, deciding it would have nothing to do with the situation. After waiting patiently in the queue of what I'm told is the busiest VR office in the state (Broadmeadows) the helpful young lady behind the counter (she really was, actually.) asks me why it wasn't just issued over the phone. "Dunno", says I, "As long as we can sort it out now, I'm a happy camper". So to cut a long story moderately shorter, a couple of keystrokes later had me a shiny new VIN printed out ready to stamp on the draw bar and an inspection booked.
Now I have a deadline to work towards - got two weeks to get the trailer ready to register. I'll add all the camper bits once that's done.

This weekend, I'll hopefully be putting the floor, sides and gates on and it'll really start to look the part.

I finished enough of the trailer to get it registered a week or so ago. The camper top is not fully installed, there are no tie-down points and no tool boxes, but all of the requirements for registration are done.
Speaking of rego, the whole process was a joke - all the woman was really interested in was the width, length and tare. I'm not even sure she checked that lights were fitted to the back (I held the tape for her at the rear when measuring the length), let alone if they worked or not. No confirmation that brakes were fitted, or if they worked, no confirmation the the VIN on the draw bar matched that on the paper work, no check for the required reflectors. All these items and others were present and functional, the VicRoads employee just didn't bother to check them. I wonder how many dodgy trailers get through this way, giving the owner-builders who do bother to do it properly a bad name?
Who cares, I suppose. Mine is now legally on the road, so I'm happy.

I just now have to finish my last uni assignment this week, put a couple of full-time weeks into finishing the camper set up and I'm off on my trip.

The photo shows the trailer with the camper top just sitting in place as I play around with how it will be fixed down and how the cover will now be fitted. The top was designed for a 6 x 4 and I've made a 7 x 4, so to allow the rear gate to open, the top has to be pushed rearwards to the extent that there is no longer room on the underside of the top for the shock cord loops to mount at the front (there enough overhang on the sides and front for them to still work). Ill have to mount some hooks on the outside face of the front gate and hope the lack of a full tuck under of the cover won't allow any water to get into the tent...

Some folk have a rope track on the front of their trailers and slide the front of the cover into that, but that aint possible without some work done to your cover. Then of course that drop down door kinda kills that option. Hint, the shock cord wont fray as easily if you cut it cleanly and burn the ends, hot knife preferably, but a butane torch or lighter will do. Personnally I recon continous bungy cord is the go over individual loops, but that is just my 2 bobs worth. Please dont tell me the camper hasnt got tape into the roof to keep the water out! [shudders] Had a bit of a run fixing campers with tape over the seams of late and all I can suggest in this case is take something to throw over the top.Not sure of your previous experience with tent trailers but when putting it up/down be careful how you do this. When working solo I use the bottom end of an awning pole (with stopper on of course) and push the bows over. Gravity usually does the rest. That way one is not putting near a much stress on the stitching. Another point to consider is have a look at the pivot point where the camper bows connect to the trailer. Many have a problem with pinching the fabric in this area. Have seen plenty where they dont bother even rounding off the steel work. Pin pricks in the fabric or worse like torn flyscreens etc... you get the idea.Sorry if I am seen as hijacking your thread, but I would rather point out a few things now than later. We have a steady stream of campers in for repair from the cheapest to 25 grand units here so one gets to see a lot of things.Jatt

Originally Posted by jatt

Sorry if I am seen as hijacking your thread, but I would rather point out a few things now than later. We have a steady stream of campers in for repair from the cheapest to 25 grand units here so one gets to see a lot of things.

Mate, hijack away! That kind of info is exactly what I want to hear.

Originally Posted by jatt

Some folk have a rope track on the front of their trailers and slide the front of the cover into that...

I assume you're talking about sail track? If that's a successful option, I'd consider the modification.
Just too lazy to have stopped the ends of the shock cord yet. Should have done it straight away, I know.

Originally Posted by jatt

Personnally I recon continous bungy cord is the go over individual loops, but that is just my 2 bobs worth

I had considered a continuous cord, but thought a single break of an separate loop would have no real impact, while the same break in a continuous line would be catastrophic. What is it about the continuous set up that you like?

Originally Posted by jatt

Please dont tell me the camper hasnt got tape into the roof to keep the water out! [shudders]

Can you elaborate a bit there. Sounds like something to keep in mind. Tape, as in a strip of reinforcing canvas stitched over a main seam, or a duct (or other dodgey 'solution') tape repair over leaking seams? Under my carport is the only flat spot on my block and I now can't open the tent up on the new trailer without shortening the middle bow (a pain in the R's. See below), but i'll take some photos on the weekend to show what my system is like.

So I gather you're telling me NOT to keep opening the tent up by grabbing a couple of hands full of wall ?

Pinching at the bow pivots is something I keep an eye out for. I have avoided it so far by pushing the gathered wall outside the bows and then folding the material back over the bows when they're flat.

The tent is a cheapy import from one of the large outdoor stores. I couldn't argue with the price as a barely used second hand unit when I bought it last year. I plan on using it for another year or two before getting rid of it in favour of something locally made - good canvas, good flooring, YKK zips, that sort of stuff. The worst part about the one I have is the cheapo zips and the embarrassing pole extension mechanism. The bow poles themselves are not too bad, but an m4 thumb-screw running through a tiny nut inside a plastic sleeve around the outer pole is a joke. Nut threads itself after a couple of uses and no more tighty-tighty. Solution was drilling a hole at the appropriate spot through the inner pole and put a pin through the lot.

I'm stuck with the bows (I can live with that) but the awning poles are nothing but cheese and they use the same useless adjusting mechanism. I have been told Supapeg poles resemble ducks testicles. Can anyone confirm this or suggest another decent adjustable pole manufacturer?

Thanks, jatt

1. The rope track we use is the same stuff is what is used on caravan awnings. It may be also called sail track not too sure.

2. Continuous just tie a knot in it to get you home. Thinking more about it now, those singles you set up will be fine as a lotta places sell it by the mtr, so no real probs.

3. A lot of the cheaper campers I have seen in recent times have an ahesive tape thats simply stuck over the sewn seams. In other words they know its gunna leak, so they try to patch it up.

4. Its a little hard to explain the way I do it on paper. As long as you arent putting excess strain on the stitching, cause it can open up the holes that the sewing machine punched thru the material to feed in the cotton. Its best to have a person each side when putting it up/down, however that of course isnt always practical. Try pushing the bows from the outside as I previously described.

5. We make up a material cover for the pivot points. As you are conscious of the potential for damage here you should be fine. If they brackets are square/sharp, then I would round em off and clean em up to reduce chance of damage.

6. The bows yes u can do something about this and operate, of course this does cost money to fix. Blow my own trumpet here... we do this a fair amount. Its a case of replace some if not all of them and usually how they operate. Still got one in the yard to fix. Of course one has to keep an eye on cost here as it can add up fast, especally if there are repairs to do on the camper at the same time. Unfortunately for the customer this is generally the case by the time we see them.

Seen some reasonable awning poes at BCF.

Its certainly not a shot a people, just watching their faces when I add up the bill to fix simple design issues and use of crappy material in manufacture of many camper tops then well yeah...... what more can I say?

Good luck.

Jatt

foto to explain no.3 tape in rooffoto to explain no.4 pack up/put away. Of course there is always more than one way to do things, but this seems to work 4 me when working solo.

Gotcha. Mine doesn't have that tape on it. You have to wonder how they expected it to make any difference, or to last any more than a day or two....

No tape --- I'm glad to hear that.