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Trailer Build Diary


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(I started a blog, but feel a forum will be better for comments ect. Thanks Paul and Terry for your comments so far)


I built my Westfiield last year and have a nice home for it in my garage. Due to work I am due to move in October and where I am moving to there is no garages - I also tend to move every 2 years and can't guarantee if I will have anywhere to store it. My solution is to build an enclosed trailer. I explored many options including purchasing a Brian Williams trailer, but spending the same on a trailer as I have done on the car is a bit silly and I don't have that cash lying around anyway - so thats definitely not an option! I researched car trailers quite a lot and my next option was to buy a car trailer and build a roof over it (in simple terms). But again, car trailers are quite expensive and also pretty heavy as they are usually not designed to take additional structures on top - so it was back to the drawing board.

I found some people who had used caravan chassis to build car trailers and that this was a possible option. I wanted to make sure that my trailer was strong enough and this would be my main issue. So I set about looking for a suitable donor caravan to destroy in revenge for its years of slowing motorists on the narrow roads of Devon  ;). After trawling e-bay and having multiple sales pulled out from under my feet I started to despair. This was until I found a caravan breakers only 5 miles from me with chassis bare and ready for action! 

The chassis cost me £130 which I felt was the best option. Looking at the individual components suspension, braked hubs and braking towing hook this price would save me loads and give me the basic chassis to build upon. 

This blog will show the progression I have been through so far and I will continue to update it with loads of photos. And for those of you who like big mechanics and trucks - there will be some of those around in the background too!!


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So her are the first pictures of the project:




This is the trailer as I bought it. Notice the single axle - which was not what I ideally wanted, but this trailer axle has a weight limit of 1450kg so roughly the weight of my car and the weight of the trailer (plus the extra stuff I'm going to build on it) should not exceed this weight as long as I keep it light. I do not have a tow bar on my car yet (another project!!) so I got a mate to come with me a pick it up. 




Here it is I'm my workshop. I think its a little too long, but should be able to be cut down a little at the rear. I want to keep the wind down legs for stability during loading/unloading so when cut down these will need to be remounted. 


The wooden top of the trailer as seen at the moment is polystyrene sandwiched between 2 very small pieces of ply wood. This is not going to offer anywhere near enough support and strength and also has some very heavy steel mounts on the bottom which is weight I want to loose through a sledgehammer diet!!




Notice said sledgehammer and resultant mess!! Most of the bolts were pretty seized so they got the angle grinder treatment with the cutting disc. This thin layer of fairly weak materials is stronger than you think and I actually developed quite a sweat in the process.




Crash diet complete and I have the basics of the chassis. The framework seen here is all galvanised steel and is pretty strong in most planes. Laterally it will twist, so this is an area where it will require a fair bit of strength. I am planning on using mainly aluminium for the trailer to keep the weight down and will try to use clever structures to maximise strength without adding to much weight. 


The axel is obviously not galvanised and has taken a bit more punishment than the rest of the trailer. Its going to come off and get a complete rust treatment. Also the hubs are going to be stripped, serviced and the brakes also a good seeing to. The brake cables are pretty seized and actually I ended up cutting them off. A nice shiny new set was bought from e-bay for not many spondoolies!




I think that might be some horse hair - I might actually have a gypsies caravan!!!


So the first step to building it up is going to be the outside frame. This will give me an idea of how big it needs to be and where it requires extra strength as the weight of the top piece is going to rest on the outside frame. I have included part of the wheels, but not all, in the frame. This will give me a little extra width and require a very small mud guard on the outside, without creating a monster wide trailer. 




The first outriggers which I have put on half way down the trailer are really strong and extremely lightweight - again made from aluminium. 




Whilst my aluminium welding is not beautiful - it is strong and actually getting much better now that I am getting lots of practice!!

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Just a small question and it will have implications on whether I buy a trailer or fabricate one as you. Have you checked whether you will need any other form of "vehicle" test or a vehicle plate as most  trailers and caravans have. I believe you will need one and if you have investigated how you get it plated would help me out. A friend of mine has a similar trailer build as yours will become, but apart from the original axle plate has no real credentials. he may leave himself a bit exposed to road side VOSA checks. If you use the caravan plate; will the gross weight be sufficient to have a 750kg car including spares on top of the chassis. It may work out but you may need to do some more sums if you haven't already, or get it plated ?. Apologies for p*ssing on your parade somewhat but you could have problems later and I am interested in case you have resolved them, in which case I will be doing the same. Seems to be a simple way to proceed as long as the build is sound. Another quick one, he had to move the axle position along the chassis to get the car to balance correctly with the correct nose weight.


I will watch with great interest.


Bob :d

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So, I mentioned the twisting of the current galvanises chassis. The axle itself provided a lot of support to stop this as well the cross beam at the front. The main area which is liable to twist is the rear where there isn't much support at all. This is also the area where I need to concentrate on the strength as this will be point loaded during loading/unloading of the car on ramps. I have therefore added this beam, which is mega light weight and very strong. 






It was made from 2 aluminium 'L' shapes placed 90 deg round from each other and putting shaped spacers to separate them. The end caps provide a good bolt on point to mount the beam onto the chassis. The result - mega improvement in strength throughout the whole rear of the trailer at virtually no weight gain.


Next the axle was whipped off and given a rub down, rust treatment and paint. I have also completely serviced the hubs and brakes, but due to how much of a dirty job it is, I don't have pictures for fear of completely grubbing up my phone.





So I kind of forgot to take many pictures at this stage. But I strengthened up the rear of the trailer and mounted the 2 wind down legs on the rear to give more support. The beam which I created was a little low and needed bringing unto height - so some small spacers were added. 




You can also see the nice shiny new brake cables which are the long-life uprated ones. I thought that as its going to be sat as a garage most of the time that this was the better option. 




So, this is the chassis mostly finished. I have added a longitudinal beam from the front to the axle. This will give support down the centre of the trailer. I have also put some more supporting brackets behind the wheels as there was a little flex in the trailer here. It doesn't look like there is much metal there and a lot of it is not massive chunks of steel, but its very rigid, extremely light and strong. I am using ply wood to top the trailer with, so this will add further strength to the structure. 

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Captain Dan, You're fired - you made the floor dirty!


(reminds me of "He's fallen in the waaaaater")

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Thanks for your thoughts. My aim is to basically use the same plate that I have for the the original caravan and that way I believe (leaving myself open to being corrected here) that when new VOSA checks and certificates for trailers come into play because it was built prior to the implementation it will not require recertification. Its a bit wishy washy though. It will not be on the roads much though as it will mainly be used as a store. You are bang on though, I will have to be very careful with the weight and I have worked it out although roughly with a degree of accuracy. I am not sure I will have room for these spares you talk of! With regard to moving the axle, I have now reached the stage of putting the car onto it  (but not posed these pictures yet) and it balances well with a fairly light nose weight. Apparently I am aiming for a nose weight of no more than 100kg. I have a few more things to go into the front too. 

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Looks very good so far

What the floor made of and do you need extra support under the wheel load areas

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Terry - Im hoping to get some more pictures up tomorrow as to where I currently am. The floor is made from ply and I am intending on putting chequer plate aluminium 'runways' where the wheels will be. The wheels sit over the original chassis when the car is loaded and don't really need any more up port than currently installed. Its very stable and there is little to no flex across the whole floor area. 

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Sent my first post before seeing the photos and the obvious high standard that you are working in and to, apologies if I appeared a little critical. This is certainly the route I would go to avoid the major cost of a new trailer and it will be built to your own requirements. Be careful of the 100kg noseweight as some cars only have a max of 75kg as per the tow hitch plate which is not necessarily the same as the cars data spec. I know my Passat is the lower figure and it also makes it easier to manoeuvre by hand n.b also easier to unbalance. Many stories of people getting into caravans or trailers whilst unhitched and tipping them up, unlikely here. Not many cars take the higher 100kg figure. Al'ls looking very good. Do you have the facility to weigh the chassis as you go and you can juggle the weights a bit. Sometimes caravan manufacturers re-plate the chassis to higher levels on request. My van is plated something like 1060kg which doesn't give you much for the bare trailer but I think the Alko chassis is again different. Good luck with the build it is looking very professional. My concern was based by the way on Caravan club warnings about overloaded vans which when you consider we generally have 200kg available for additional load is not a lot and VOSA have for a few years been stopping vans in their roadside checks, which I may add is fair enough as an overloaded van may be dangerous and if you've ever seen one self destruct in a motorway crash is something to be very much avoided.


Keep the photos coming


Bob :yes:  :d

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Using caravan running gear is a great idea, which is why mine is a twin axle based one. The problem now is that all self built trailers have to unde go an IVA especially for them. Of course if it was built last year there is no issue at all, if you see what I mean. :devil:


As for the plating and weight issues, mine could carry two tonnes as the caravan it was under was huge, all you need to do is set a sensible weight, VOSA are not stupid and make sure your tyres are up to the job. Mine now has 8 ply van tyres so again should be no issue.


Also with a single axle, I would have made it the length I needed by adjusting the chassis lenght accordingly at both ends and make sure you use some form of anti snake device. I have towed thousands of miles with both car transporters and caravans and loading balance is crucial with a single axle.

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Thanks for all the thoughts and ideas guys - please keep them coming. I am updating the pictures as and when I can and hopefully I will actually have updated you all with where I currently am with the build. I don't actually have a tow bar on my car yet, so thanks for the point that each tow hitch may have a different point weight. I am hoping to put a Westfillia removable tow bar on my Seat Exeo Estate - so definitely something which I will have to keep in mind. I have not weighed the trailer yet, but do have the facilities and will probably try and do that this week to give me an idea of what I am currently at.


So the next step which I took was to put the ply-wood floor down. I wanted to get marine ply but for a number of reasons I used normal ply and have treated the bottom of it with waterproofing and paint. The floor has been silicone sealed when installed on the trailer. Some photos later will show the floor not in the trailer as I took it out to do the welding of the upper so I didn't burn big holes in it! I have since then sealed it in. I am planning on coating the whole underside of the trailer with a pretty gooey undercarriage sealant that we use on the big green stuff to protect it from pretty much everything. 




For those of you wondering if we ever actually work on what we are supposed to in this hanger - we do but this end is for projects and own work. It keeps my lads skills up on smaller stuff - I vital part of their development ;)


The next step was to prepare all the upper framework. I have tried to keep it lightweight, so aluminium has again been used to maximise strength to weight ratio. I am riveting on aluminium sheet as the cladding so am drilling all the holes from a template on the framework before it is welded together. I had a mammoth drilling session where i ended up not ever wanting to see a drill again! This is the result - 




I then started to weld them together in hoops 1m apart along the trailer. The width is 184cm and the height is 160cm. They will be joined at the top corners to for the top ends of the trailer.




I have used corner brackets to maximise the strength and aid me in getting them as accurate as possible. The last thing I want is a lopsided or twisted trailer!









I completed the rear sections of the framework and halted there as I didn't really know exactly how I wanted to finish the front of the framework. I had toyed with the idea of rounding it off, but aluminium is very difficult to bend. Even with my impressive array of tooling, I do not have a roller for rolling metal - which was exactly what I really needed. SO I opted to use an angular slope on the front. The front of the framework comes up vertically to trust below the height of the back of my estate car. It then rises at an angle (that I can't exactly now remember) to allow for a bit of aerodynamics (not much for a brick though!).




So I have now actually got most of the sheet aluminium on the trailer too and here is a quick photo to show where I currently am with it.








I will update more very shortly with how I made the ramps and what else I have planned - especially the electric charging circuit and winch.


Please do keep the ideas and thoughts coming.

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Great so far

Are you thinking of putting a side access door in?

How are you going to strap the car in place particularly at the front end of the trailer which probably needs wheels chocks

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