Building a small covered car trailer

[wannaberacer60]

Hi All,

I am new to this forum but would like some info from Yonnee and other experts in the area.


I am just a about to acquire a small open wheel racing car (Formula Vee) and want to build a suitable trailer. The enclosed ones I have seen are all over $6K + and as I have access to a commercial quality metal shop and good welders I think I should be able to to better that than and get what I want. much cheaper


My ideal is a trailer with internal dimensions of 4- 4.5m long and 2m wide., enclosed with internal height of about 1.8m


The total weight of car and tools, fuel, accessories etc should be about than 1000-1100KG and I was hoping to have an all up weight of less than 1500 kg so it can be towed by relatively small car, subaru liberty waggon (not into big4 X 4 and V8's).


It will not do huge distances mainly Sydney to Goulburn and very occasionally interstate trips.


As it may be towed by different vehicles i presume that it would need mechanical brakes rather than electrical and does it need to be dual axle or would a single axle suffice.


I have looked at the frame designed by 09sr5 and it would seem to be massively overbuilt for my needs, but I don't want to skimp on strength or quality.


I presume that I could get away with lighter steel than 09sr5 , what would you suggest. For the enclosure frame would 25mm SHS be suitable. What floor would be suitable?


I have a link to a trailer being sold which is my ideal but I don't know whether it can be accessed.

Enclosed dual axle Trailer — Formula Vee Australia (http://www.fvee.org.au/Members/nsw/enclosed_trailer_purvis)


Is it possible or practical to buy second hand axles, hubs etc from a caravan wrecker and would it save much?


Thanks for your help

[antoni]

Hi you will need to go dual axle, new parts are best and easier to work with.
With the subaru liberty waggon I find ts on the small side.
Its just too easy for a trailers to push a small cars around going down hills ect.
Tony

[Yonnee]

Sounds like an interesting project, especially the bit about "aquiring" a race car.

Firstly, I would not scrimp too much on the running gear, new axles, springs and coupling shouldn't break the bank and you wont have to worry about things like bearings and brakes for a while. It also allows you to get an axle exactly to your specifications in terms of length and capacity.

If you can keep your weight under 1500Kg, you can get away with a single axle setup, but you'd continually have to be aware of what your putting in the trailer. Building it as a single axle, you'll also need to be fairly accurate with your axle placement. Too close to the centre of gravity (not necessarily the centre of the trailer), and the trailer will not tow well, constantly trying to swap ends with itself and you. Too far to the rear, and the trailer will tow fantastically, but will probably exceed the towball weight rating for a smaller tow vehicle.

As you say, if the trailer i being towed by more than one tow vehicle, then over-ride brake would be the way to go. As for which type... Mechanical drum is by far the cheapest, but there's quite a delay in braking effort as quite a bit of movement is taking up the slack in the cable, and you can't have it too taut or the brakes will drag and overheat. Hydraulic is a bit dearer, mainly due to the coupling, but the hydraulics will work pretty much instantly, as long as everything is kept adjusted and maintained.
But, ask yourself, how often would it be towed by other cars? Because once you've had Electric, you never go back.

You're right, 09sr5's is a fairly heavy duty trailer and could quite easily handle 4000Kg. Yours on the other hand would get away with 75x50 main rails and drawbar, and 40 square for the rest. 25mm sq would be perfect for the upper frame, and remember, triangles are your friend.

The floor is a personal choice. Timber can be just as heavy as steel as it has to be much thicker. And with timber, once you cut it, it's difficult to rejoin. A steel floor is lighter for similar strength, but on a racecar, I would steer clear of checkerplate, mainly for where the wheels go, as the tread on the checkerplate tends to make and leave an impression in your soft, sticky race rubber. If your budget will spring for it, smooth 3mm aluminium plate would be ideal. Lighter than steel, and no need to paint it.

Good luck with it, and keep us posted on your progress.

[jatt]

If you can keep your weight under 1500Kg, you can get away with a single axle setup, but you'd continually have to be aware of what your putting in the trailer. Building it as a single axle, you'll also need to be fairly accurate with your axle placement. Too close to the centre of gravity (not necessarily the centre of the trailer), and the trailer will not tow well, constantly trying to swap ends with itself and you.

Have you tried towing a "lighter" weight tandem on the Suburu? If it was me I would go the tandem, I just like the way they sit out on the road. Then again I have a Falcon Tradesman ute to tow one with.

antoni sounds like he has had experience towing with a Suburu. Have no personal experience with one myself, but would some suspension work on the back help out here? At least so its sits better when towing. Yes I know ideally there is no substitute for extra tow vehicle weight.

As the man says, electric is ideal. Ally where possible/practical to keep the weight down.

[buildspacetrain]

Hi Wannaberacer 60,
Have been building a tandem similar in size to the one your after. (see 'Trailer for long loads' (http://www.woodworkforums.com/f184/trailer-long-loads-111868) in this forum.)
Size is 4.5m x 1.5m with 1.5m drawbar. 75x50x3mm main frame and 100x50x3
drawbar
All up I have spent $2700.00 and am in the final stage of painting.
This includes new tyres and fancy white rims.
While it might be cheaper to build it yourself, it is a lot of hard work and a fair bit of time. You really must love the challenge of doing it yourself or it's not really worth the hassle.
Me, I just love the whole workshop thing and couldn't care if it cost twice as much.
Write out a list of all components you will need and be surprised at how long that list will be.

[antoni]

Hi no did not have a Suburu had some small cars not for long.
They can get pushed a round in the wet and I did in 1100 kgs statwag once towing a small race boat just mowed the grass bit.
The last 15 years been useing a F250 for towing they go they stop , just no good for parking in the city,,,,,,
Tony.

[weisyboy]

Hi no did not have a Suburu had some small cars not for long.
They can get pushed a round in the wet and I did in 1100 kgs statwag once towing a small race boat just mowed the grass bit.
The last 15 years been useing a F250 for towing they go they stop , just no good for parking in the city,,,,,,
Tony.

or fuel economy.

i would be be wary of towing that mutch weight with a small car.

[antoni]

Hi f250 on gas and a round 4ks to the ltr , also got a comie vn 6 to 7 ks to ltr ,
Its not as good when towing with the v6 uses more gas.
The boat was not big, as it was a race boat 4 cly hydro on single axle trailer.
just wide . best to have tow unit bigger than what you are towing.
Dual axle is so must easer there not so must load on the tow car .
Tony.

[StrathfieldMens]

Hi All,


Thanks for all the constuctive suggestions. Preliminary thoughts as follows still open to suggestions though.

*Internal dimensions 4.5m X 2 M ( this also allows for a FF which is up to 1850 mm wide which may make trailer easier to sell at later date and room for bench across front

*Drawer bar 1.5 m long 100 X 50 X 3

*External frame 75 X 50 X 3

*Internal cross members at 750mm centres 50 X 50X 3

*wall/enclosure frame 1.8 m high, 25 X 25 X 2

*Dual axle with electric brakes ( do both axles need brakes?) Ford wheels

*Undecided about floor and wall covering but will take all suggestions on board.

As far as time and effort involved I am a member of active mensheds many of who are retired metalworkers desperate for something to do so labour and time not a problem so fortunately will probably only have to supply the coffee and beer at end of each day.

Should have price on metal soon and have spoken to Carasel about a package for everything else,excluding floor and cladding hope to bring for $2.5- $3K which is still about 1/2 price of commercially built trailers

Thanks again

[Yonnee]

Change of user name...??

Legally, you won't need 4 wheeled brakes under 2000Kg, but it's not much extra to order the rear lazy axle with Electric mounts fitted. That way, you conversion to 4 wheeled brakes is a bolt-on fit. Single axle wise, they're good for 1500Kg, so you're OK there.

Sizings look OK. Are you going to taper the front down along the drawbar? The trailer in the picture looks good, but I would be very concerned that the drawbar looks like it only extends back about a foot or two past the front of the trailer. It should really tie back to the front hangers so your accelerating and braking forces are directly acting on the coupling and springs rather than relying on the chassis and welds in between.

[wannaberacer60]

Yonnee,

You are observant I used the the wrong account the menshed one instead of my personal account. Thanks for your comments though.

In regard to the tapering of the front I always had the impression that it was best to have a clear 1.5m from the front to the towbar but if I could grab another 500mm from this by following the draw bar angle it could give more storage room with minimal increase in material and weight and improve the aesthetics of the trailer.

Project seems to be getting bigger (heavier) and note other comments about using Subaru seems will need something bigger

[Yonnee]

How old a Subaru? You'd have to be careful what the towing capacity actually was. We, until recently, had an MY97 AWD RX Wagon, and its towbar was rated 1200Kg, and I'm not sure if Hayman Reece have a Heavy Duty option (they've removed their catalogue from their website!!).

[wannaberacer60]

Hi All,

Have received prices for the structural steel, all steel required, new and galvanised, as stated previously supplied and cut for about $900 inclusive of GST, which just means one or two long weekends with enough helpers to build chassis.

Was disappointed however with price of sheet metal, new aluminium over $2100, new steel about $1600. Am happy to use second hand material for this, does anyone know here can source 2-3mm sheet steel (or even better ally) for floor and .5-1mm for walls ( will adjust framing depending on thickness of sheet). Are there companies which dismantle damaged semi-trailers bodies or sell used sheet in Sydney, could not find any on Google and could only find used sheet in Melbourne. Assuming can source sheeting at reasonable price can build trailer for $3000-3500, less than 1/2 price of comparable trailers advertised on racing websites.

[buildspacetrain]

Some of the larger steel suppliers in Melbourne have what is called 'down graded' steel plate which is cheaper than 1st grade stuff. Might be worth ringing around and asking for down graded steel. Might be the same for aluminium to.

[Bazzmate]

For the wall sheeting, there's a sandwich type of sheeting that you might like to consider? It is made of two sheets of thin aluminium with a black polycarbonate(?) centre and is about 5mm thick. The face side can come in different colours . . . I've seen a black and a white version. You can router a deep V groove to just the right depth on the inside so that the sheet can be folded to form a perfect external corner (e.g. no need for external cover angles to hide butt joints). Wouldn't rust and wouldn't need to paint it. I think places like Metaland sell it?
Sorry, I just know it exists and looks good as trailer wall cladding. Hopefully someone else will know what I'm talking about and be able to help out with any other advantages, disadvantages, prices and where to get it, etc.
Cheers

[Gaza]

its composite cladding.

used for facides, bit exy for a trailer.

try fairview architectural they delivery to sydney everyday and the price is good, they have a few colours and sheet sizes,

if using composite you use 3m "very high bond" tape to fix to steel frame, for corners you will need to put a angle on the inside to stiffn it up, these can be glued in with a polyurthane adhesive like purbond.

to bend corners you use a "v" point router bit but grind the point of it so there is a flat spot on it. cutting sheets use an aluiuium blade in circular saw.

any questions or need photos let me know.

[wannaberacer60]

Hi All,

As you can probably gather I have too much time on my hands.

Plans starting to come together .

Got a price for all accessories, axles, suspension, hubs, electric brakes (on one axle only), coupling and all lights, reflectors etc. for $1600.

New .55mm colorbond walls at about $700 ( still hoping for seconds from somewhere). Have decided to use structural plywood for floor, can get for free and if it has to be replaced in a few years not a great problem. Will have chassis cross members and wall frames at 600mm centres to reflect material size and impart a little more strength and will also have 100mm square mesh on inside of wall frames for additional strength, protection of walls from damage and to provide hanging space and shelf support in trailer.

Still aiming for $3500 maximum cost.

[Gaza]

give a roofing suppiler a call like KFC or ridgeway they buy colourbond in the roll for use as flashings.

they could supply you your cladding in single lengths to save waste and it may be cheaper.

i think the coils are 1mt wide

[wannaberacer60]

Hi All,

Question for Yonnee or other experts

If the external width of the trailer is 2m. and as maximum width cannot exceed 2.5m will 250mm. each side be enough for wheels and mudguards. The standard mudguards I saw for sale seemed to be wider than 250mm. I could reduce max width to 1.9m but would be reluctant to go reduce any more.

Would the alternative be to have the wheels internal to the external dimensions, would look better, (as per a caravan) though I presume this would make the chassis design somewhat more complicated as would need main frame to be internal to outside dimensions with a subframe on the outside to support the walls. Do not think would be much difference in material costs though as frame material is certainly cheapest part of project.

[Yonnee]

Standard guards are 9" wide (235mm), so you could have your overall body width at 2000mm and still be inside 2500mm.

Or, enclose the guards within the body and you can build a 250mm wide bench over the top of the guards.

Or, go for the 'tubbed' look. The body at 2400mm and the guards sticking out 50mm a side and 185mm tucked inboard.

Any or all of these can be achieved as long as you plan from the start. Your main chassis rails mount your spring set, then your wheels sit outside this. The bodywork you can make whatever you want around it. The only extra materials would be longer cross rails to add as outriggers on the outside of your main chassis rails

I'll give you a tip though, make your dimensions of the trailer multiples of the sheet sizes. (1200mm wide sheets, 3600 or 4800 or 6000) Less cutting of your materials and less waste. (Hence the 2400mm width. A 2000mm body width means you have to cut 400mm from all your roof sheets.) Also, design your exo-skeleton frame with the same dimensions, so all your sheet joins are on the frame. I know it might sound like I'm telling you how to suck eggs, but things like this at planning stage, avoid those "D'OH!!" :doh:moments later on.

[Oden]

Hi

I just purchased 4 1.2*2.4 2.0mm steel checker plate for $104 per sheet new in Grafton the price range was astounding major sttel fabricator was $188 per sheet.

oden

[nevile]

Standard guards are 9" wide (235mm), so you could have your overall body width at 2000mm and still be inside 2500mm.

Or, enclose the guards within the body and you can build a 250mm wide bench over the top of the guards.

Or, go for the 'tubbed' look. The body at 2400mm and the guards sticking out 50mm a side and 185mm tucked inboard.

Any or all of these can be achieved as long as you plan from the start. Your main chassis rails mount your spring set, then your wheels sit outside this. The bodywork you can make whatever you want around it. The only extra materials would be longer cross rails to add as outriggers on the outside of your main chassis rails

I'll give you a tip though, make your dimensions of the trailer multiples of the sheet sizes. (1200mm wide sheets, 3600 or 4800 or 6000) Less cutting of your materials and less waste. (Hence the 2400mm width. A 2000mm body width means you have to cut 400mm from all your roof sheets.) Also, design your exo-skeleton frame with the same dimensions, so all your sheet joins are on the frame. I know it might sound like I'm telling you how to suck eggs, but things like this at planning stage, avoid those "D'OH!!" :doh:moments later on.
Hey Yonee like your style of advising.