The expanding
Teardrop Trailer Build
By Winston Lee
18/04/2013
Concept.
I wanted to go touring, and camping, on my motorcycle.
But did not want the complexity and all of the associated hassles of roughing it, or erecting tents. Or sleeping on the ground, or fighting with a swag, or blow up mattresses etc.
Besides that is a lot of stuff to pack on the back of a motorcycle.
So after some considerable thought I decided to construct a pull along teardrop trailer, for my motorcycle .
I wanted to incorporate some unique design features that could only enhance the pleasures that would ensue with its use.
With my limited skills and capabilities this build had to be simple and economic in design, and concept, and to use easily available and inexpensive parts, and components, and the tools that I had to hand.
I selected a readily available small trailer chassis kitset that I could easily assemble, and when completed it would comply with the Western Australian motor vehicle registration specifications. (it had the factory supplied required Vin. number etc.) And came complete with the full suspension , Spare wheel, Trailer hitch, safety chain, lighting ,and wiring loom, and suitable 7 pin plug. Etc.
The assembled dimensions of the chassis were most suitable for the intended purpose and did not need to be altered in any way.
At this time I was not overly concerned with the finished gross weight of the trailer as the kitset components weighed in at about 65 kilograms and I was allowing for a possible all up finished laden weight of around 190 to 200 kg. My towing motorcycle in my opinion is just one of the best, being a Honda ST.1300. It has plenty of power and certainly can go fast enough for me. We are limited here anyway in Western Australia to a maximum of 100 kilometres per hour whilst towing, and a maximum of 110 at other times when on the open road .
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Body Design,
I wanted to be as economical as possible with the materials needed, so I elected to construct the body from aluminium checker plate (diamond pattern), and it was to have a plywood floor.
The body would initially be a one piece shell and when finished would then be cut in half across ways and the rear portion would be attached to both the chassis and the rear portion of the floor, the floor would be in two pieces also, (details of this later).
The front portion of the floor would be on top of and overlap the rear portion.
The rear portion of the body would be perminately attached to the rear main part of the floor and the chassis. The extending front portion of the floor, and body, would then be able to slide forwards away from the rear part of the floor and body, and up the draw bar, towards the towing hitch. Supported by Teflon sliders and some small fabricated rollers.
The effect of this would be to extend the opened ,overall length of the teardrop body from the designed 1550 mm (closed length) , for towing. To a total extended length of 2400mm, This would enable a full length for a (bed) of some 1020 mm. wide, (the chassis width.) by 2000mm in length . Ie. some(50) mm. longer than a normal bed (which is 1950mm) ,and then there would then be an area of some 400 mm. deep, accessible through a rear hatch as a totally separate storage area (some might call it a kitchen.)
Access to the bed area is through the sides at the point where the body divides and can be an opening of between 800mm. to 900mm. in width, depending on your preference.
I subsequently have constructed a couple of separate cover panels which clip on to the side and the top, over the opening, these will provide adequate weather cover for the opening in the top and one side. These panels unclip when packing up and are stored on the floor of the front half, and when packing up I place them under the folded mattress, before sliding the two halves of the body together.
There is also a very light weight awning system which attaches over the opening and will give full shade and rain protection if needed.
I wanted to minimise the cost of the single most expensive components, ( The aluminium cladding for the body), Consequently the sides were shaped and designed to be both cut from a single 2400 by 1200 mm sheet of 2.4mm aluminium, don’t forget to reverse the profile for one side so that the outside surfaces will have matching patterns to the outside.
The top was cut from a single piece of 2400 by 1200mm 1.6mm aluminium . The top was cut
to be finished 20 mm. wider in total than the finished width of the outside of the body. The hatch for access to the rear storage area necessitated the subsequent purchase of a suitable sized extra piece of cladding. This was sourced at the time of constructing the two clip on cover panels.
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Chassis Considerations and adjustments
For stability when towing. The draw bar length needed to be adjusted to a ratio that is dictated by the wheel base width, (or track). This needs to be minimum of one point eight times the wheel base width. I feel that a ratio of two times is even better.
To achieve this the draw bar was extended by approx. 650mm. from the front of the chassis, this gave an approx. total length of 2300mm from the axel position.
At this time I also extended the total length of the draw bar to project 300mm past the rear of the chassis this gave me a firm attachment point for the rear of the body and also a suitable mounting position for a bumper, or in my case a place to mount the spare wheel.
As the wheel track is 1200mm. from centre to centre of the tyres, and the draw bar length 2300mm from the axel to the tow hitch, this equates to a ratio of 1.9, and I found that with these dimensions the trailer was well behaved and tracked the motorcycle perfectly and there was no induced swaying whilst underway.
Trailer Hitch
This one is quite important.
The supplied hitch is of the standard design and suitable for up o 750 Kg.
However for use with a motorcycle, I would recommend obtaining an aftermarket unit that swivels around the axis of the drawbar. This is for safety reasons, because if your bike ever falls either off the side stand, or is dropped, even at a low speed, if the hitch does not swivel, some quite serious damage will be caused to the attached hardware on the motorcycle.
Draw bar weight,
I feel that this is very important and some care must be exercised when loading the trailer, I have found that for me, a tow hitch weight of around 15 kilograms when laden, is acceptable, but you will have to experiment a little in order to find out what will suit your particular situation.
With the Easy Tailer chassis I took the trouble of dismantling the leaf springs in order to remove the second leaf from each spring. In my opinion the overall laden weight of the trailer did not need the extra helper spring leaf, and doing this actually improved the handling of the laden trailer. Whilst doing this I also slipped a piece of suitable plastic irrigation hose over the bolt that retained the rear of the spring in the slipper, this reduced the transmitted noise when the spring moves.
After assembling the chassis and attaching the springs, when fitting the axel I turned it upside down and placed it on top of the springs, this lowered the chassis approx. 40 to 50mm which will reduce the overall finished height of the trailer. It also lowers the centre of gravity.
After fitting the stub axles and the finished draw bar, the chassis was checked for squareness by measuring from the back corners to a centre point on the attached tow hitch, when these measurements were the same I also checked the distances from the ends of the stub axles to the same point on the tow hitch in order to make sure that the trailer would track properly.
When all was square the chassis assembly bolts were checked for tightness and then any joints that were suitable on the chassis were welded .
Tyres
The tyres and wheels that were supplied were 12 inch rims fitted with 4 ply high speed tyres rated for 120 kph. And 480 kg. I found that an inflation pressure of 25lbs was suitable for me.
Lights
Standard trailer lights, ie, side, running, stop, and turn indicators, with incandescent bulbs were supplied with the chassis components.
I felt that these were quite satisfactory for my needs, but if something up market was required you could obtain some suitable, led type, there is a very wide choice on E Bay.
Sliding Floor
This was achieved by making several sets of rollers and then inserting them in the main floor as shown, see the photos for illustrated details.
The rollers were constructed from a piece of 1 Cm. Thick nylon cutting board. I used a 30mm. hole saw to cut out the wheels, and the axles are from some ground down 5/16 inch bolt shafts, these were then held in place with some appropriate stainless steel strapping, and countersunk ¼ inch bolts.
With hindsight the roller idea is probably a bit too much , I now think a suitable result could be obtained by using thin strips of Teflon fastened on the main floor, (glued), and the sliding surface faced with something like melamine.
Internal divider
This will be needed in order to divide up the internal space as you require as well as providing a very strong bracing for the sides and also supporting the top.
This was constructed from a suitable piece of sign white. Bent to shape to give recessed area for clearance for your feet, and to make a shelf in the rear storage space, This divider adds a tremendous amount of needed reinforcement and stiffening, to the sides and the top.
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Trailer build
Step 2
Sourcing parts and hardware.
1 The basic trailer chassis,
Carlex Pty. Ltd. (Easy Trailer Service Centre) Email sales@carlex.com.au
830TA Trailer Trailer Model LCI-830TA
Spare Wheel, 4 Stud
Trailer Stand
Tel 1300 881 787
These people have a comprehensive range of product , contact them for their product catalogue etc.
See appendix 1 for the specifications
2 The aluminium sheeting for the cladding, and the right angle al. extrusions etc. contact any of your local sheet metal suppliers for their selection of product and prices, I used aluminium diamond pattern checker plate for both the sides (2.4mm.), and the top (1.6mm.) Full sheets 1200mm. by 2400mm.
2 General hardware items. Locking Latches, and general
3 assorted bolts and other fastners etc, The local Motor vehicle and hardware parts supplier.
4 Screws, and Sealed aluminium pop rivets, Bolts etc. The local Bunnings.
5 Wooden components, plywood etc. Bunnings.
6 Silastic adhesive Bunnings.
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STEP 3
SPECIAL CONSIDERATIONS
West Australian Government legislation.
See attached extract for current requirements.( if I can find it)
For your build you will have to consider some if not all of the following points.
1 Weight
2 Width
3 Height
4 Lighting
5 Towing speed (Tire ratings and sizes)
6 Draw bar length
7 Tow hitch weight
8 Overall weight
9 Tyres , Specifications, Sizing, Speed and loading,
10 VIN. Number
11 Vehicle licensing
12 Driver (licensing) requirements.
13 Fuel consumption. Towing vehicle
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STEP 4
Insurance and Legal Considerations.
1 Check with your Insurance providers as to their requirements in regard to your special situation and requirements, and to ascertain what disclosures they will require from you.
2 Will you and your Motorcycle comply with their requirements? or will you have to canvas the providers to find one that will be interested in your business.
3 If you choose to use any of the information provided in this blog, it is solely at your own risk and the author is absolved from any consequences or happening that might ensue by your actions.
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Appendix 1
WWW.easytrailer.com.ausales@easytrailer.com.au
Ph.1300881787
Basic trailer chassis, information.
Trailer specifications
Model 830TA Chassis Trailer-Rigid
Bed size 1220x1016mm tare weight 65 Kg.
Compliance ADR/ECE .
Springs HT. Slipper (660) Kg.
Wheels 12” white Spoke Steel (5mm)Tyres 60 Psi, 4 Ply, High Speed
Hubs/ Axle 4 Stud, Cast Iron(990) Kg. Bearings, 2” Fully Tapered (990) Kg.
Bed Height 475 mm. Coupler 50 mm. 750 Kg.
Coupler Height 410 mm. (Hitch) Frame “C Section 1.5x2
Hitch Standard Regulation 750 Kilogram
Safety chain Regulation stamped 1000 Kg.
Drawbar 700mm,-2.5”x2” Lights ADR Combination Type
Wiring 7 Pin Flat Loom
Lights Combination/stop/running/turn signal indicator. With Optional / Amber side lamps
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Appendix 2
Concept drawings
The following few drawings are an attempt to show some of the design concepts and ideas that I used to ratify my final design, in some instances the final design changes quite a lot from these original sketched ideas and this was because of having some new ideas and also having to adapt certain features to suit the available materials etc.
You will get the idea.
These were my initial sketches which I used to prove the concept.
The final build changes somewhat from these examples. As some minor modifications were incorporated as the build progressed, and I had the opportunity to improve, some aspects of the design. As I thought of them.
I actually built things to fit as I went along and ideas came to me
All the measurements and notations shown, are nominal values only. But I made some effort to try to make the drawing to scale.
The dotted vertical lines that show the centre portion of the floor lifting vertically, this was not used in the final build, as I decided to make the floor in two pieces, then to divide, and then slide over itself.
The final size of the body was dictated by the stock size of the kitset trailer chassis, and the overall size of the top of the body was dictated by cutting it out from only one sheet of aluminium.
The drawer bar was lengthened to 1800mm from the axle and then 300mm rearwards to provide extra support for the body and the spare wheel.
The zig zag dotted line towards the rear shows the internal divider which separates the rear storage compartment and also adds a tremendous amount of bracing, support for the roof and stiffness to the body.
The square item on the draw bar could be provision for a esky or other storage area, but that item would have to be removed when opening out the trailer body. I felt that this was not practical, and my esky is carried inside whilst travelling.
Well that is all I have to say folks.
I hope that you found my little exercise interesting and possibly informative.
My next exercise is the construction of a single wheel (uni go) type of pull along trailer.
This utilises as the main components the front wheel, complete with the telescopic forks, and the chassis of a discarded scooter. Then there will be the body build and the construction of the special draw bar and hitch coupling.
Cheers.
Winston Lee Western Australia.
Email meontop@hotmail.co.uk
