light trailer rebuild

[ned]

hi all.

so i bought some tyres for my truck, theyre 40kg each and 37 inches in diameter, theyre big

I had no way to collect them though. Plus i have no way to buy steel or transport bulky items, like bits of the truck. I have a 2 door coupe as a daily driver, its fun to drive, and i want to hang onto it, but its pretty impractical. A trailer was the answer. so i built a hitch for it at the weekend

The guy that sold me the truck, lovely fella, sold me a trailer for a hundred euros, which is unheard of, so im very pleased. I'm looking at it as a good base that i can rebuild to suit my needs.

the thing about it is though, if i load those tyres onto it, a lot of the weight will be on the rear suspension of my car.

currently the trailer is great to tow, you wouldnt even notice it. If i alter it, shorten the distance between the wheels and the towbar, like below, will that affect the dynamics of how the trailer behaves? will it be more jumpy / skittish?

answers on a postcard lol, ...No seriously, - any help , suggestions or advice appreciated, thanks for reading

 

[brightspark]

the wheels want to be in the center of the trailer and when fully loaded a slight weight to the front and it will tow fine if back end heavy or 2 heavily weighted to front it well weave all over at about 50mph upover i can tow mine at 80mph np on private road mind when i have it empty a carry a bag of sand round in it as it bounces all over when theres no weight on it

 

[Rig Pig]

The wheels of my small Daxia are in the centre, it tows very well.

 

[brightspark]

heres my home built its 40 years old i wouldnt part with it. its been filled with wet concrete had a full size lathe in it a large milling machine and a large elecro magnet in scrappy sat on it and its suvived

 

[jpmillermatic]

I built a trailer that is here on the forum (e36 trailer) and the weight is just about centered with a slight nod to tongue heavy when empty. If I have the brain turned on when loading it, I can get a reasonable tongue weight without overloading the suspension of the car. ....I think I end up with no more than 70-80 lbs on the hitch loaded...this represents one average person's weight in the rear seat......You are correct: the farther back the wheels are the more stable it will tow... but what seems to work well is when the wheels are just a little back from center.

You can measure the tongue weight by getting the tongue level and using a bathroom scale placed just under the trailer hitch. (or just guess by lifting it yourself....)

JP

 

[octo0072000]

that trailer looks like it was a trailer tent not meant to carry weight very light frame etc
has it any id plate on it

 

[pedrobedro]

Our trailer tent is rated at 750kg, it is braked though. They are heavy when loaded up with all the canvas and mattresses and cooking gear so are good enough to convert to a trailer for reasonable loads. Putting the wheels in the middle of the bed will not do any harm to the handling and you need some nose weight anyway just don't put too much weight on the back suspension. If the car is designed to be fitted with a tow hitch it should tell you the maximum nose weight in the book. If it is not designed to tow you should not fit a hitch.

 

[ned]

sound for all the replies guys, great stuff, thanks for the info.

pedrobedo, thats interesting. it had holes in the rear of the chassis that looked like they were for attaching a hitch.... The car is a levin, loosely related somehow to a corolla , so framewise i reckon it'll be fine. The rear suspension tho looks kinda complex, more complex than your standard fare, and i doubt that it will like it. Certainly it wouldnt like a caravan lol.

it was a trailer tent and its rated to 365kg. which is totally fine, the combined weight of the trailer and the tires should be in and around 250 kg or so, and any of the bits I've thought about hauling are light too, relatively speaking.

jpmillermatic might think about going 50/50 -

shorten the hitch member a small bit to keep the distance from the towball

and push the bed back a bit, to get it more centered over the axles, but still have it slightly nose heavy, to save the car suspension.

good good.

 

[BBD]

I'm just about to start building a trailer and will be putting it through the British IVA test to get it approved and all the research I did came back showing the wheels need to be positioned at 60% from the front. i.e if trailer is 100cm the centre of the wheel should be at 60cm back from the front.
I also double checked this on a trailer I hired and looking at specs on other decent trailers.
Hard to tell from your photo, but it doesn't look too far off.

 

[ned]

BBD thats great info. not sure i understand it fully, maybe you can tell me if i have this right?

what about track? I was thinking of widening the axle so theres more carrying space in the bed. Since its indespension this is an easy thing to do.
would that have any bearing on stability?


im not good at maths but it looks like pi is a factor here

 

[BBD]

It is late and I probably didn't explain it well lol... but wheels should be positioned further back from centre. so if trailer is 100cm long, the centre of the wheel should be 60cm when you measure from the front and 40 cm from the back of the trailer.

There was no set rule for this, but there is info on the coupling weight and if the wheels are too far forward you could end up with negative nose weight... which you definitely don't want.

As for width, I wouldn't make it wider than your car, trailer I'm building will be 7ft long (about 4M with drawbar / hitch etc) and 5ft wide with external wheels and I'm aiming for a total width of around 2M maybe just a tiny bit over that. I'll be towing with a Shogun which is about 2 meters wide.

 

[BBD]

Didn't see pic, but yes, that's it.

 

[jpmillermatic]

I would move the wheels and wheel wells up a bit and you should be fine. 55 to 60 per cent rearward bias is good, giving you positive tongue weight even with an unloaded trailer.

If you are not carrying anything too heavy, you should be fine. just take it easy on the transmission and maybe change the fluid and filter if applicable, or top off the tranny fluid and any other associated maintenance in that area.

some cars are rated NOT to carry trailers specifically for liability reasons...most cars can carry a little utility trailer...you just have to know your cars limitations and be realistic with what you do decide to carry. roasting your transmission because you decide to bring home a nice 2 post car lift or machining lathe is NOT realistic with a light duty set up!...

JP

 

[jpmillermatic]

by the way...nice job on the hitch!

JP

 

[ned]

sound lads, thanks ) thats all the info i need really. Now i need steel and some spare time.

 

[stucktoweld]

The trailer should be strong enough to take a load greater than its 375 load
What limiting the max load is the weight rating of the axles. They will be rubber suspension units
http://www.indespension.co.uk/Units-c/w-Hubs.html

You can always beef up the subframe of the trailer and change the tow bar to an A frame design
Well within your capability seen you towbar...neat
You have no problem with IVA test trailer is too old for that ;-)

 

[ned]

thats nice of you to say . I handnt considered an a frame design.

there are restrictions here on what im allowed to tow with my normal car licence, which is basically anything up to 350 kg

bearing that in mind i dont want to add that much weight (more steel) to the trailer, decreasing its payload.
also i think that the current design is grand fo that weight, lol,- if i build a heavier duty one then ill be tempted to haul heavier things, thus breaking the law.

not that im an angel, im not, so the less breaking the law i do the better.

Can i ask please, what aspect of the suspension unit is rubber? i dont actually know how they work, i woulda suspected something inside the box is wound up.

 

[stucktoweld]

Simply there are solid rubber rods or bands that surround a shaped bar inside the suspension unit as the axle turns the rubber gets compressed simple
That's why overloading damages the suspension unit terminally
Sorry I can't find an illustration of this maybe someone else can oblige

 

[brightspark]

Simply there are solid rubber rods or bands that surround a shaped bar inside the suspension unit as the axle turns the rubber gets compressed simple
That's why overloading damages the suspension unit terminally
Sorry I can't find an illustration of this maybe someone else can oblige

there was a post on the forum last year someone cut some open and renewed the rubbers and welded it back up . not that i would fancy doing it mind as i generaly load mine to the hilt sometimes and even have to over inflate the tires

 

[ned]

cheers

well i peeled it back to bare metal. I like that its light, but its a bit too light.

I'm thinking what ill do is just build a completely new trailer, and re-use some of the hardware from this one. I'll keep the drawbar length the same and just extend out the back a bit to get the length and balance that i want.
theres a lot of pics of 4x6 trailers online, so lots of ideas. currently im liking this one. not sure where id get the mesh from.

another problem i foresee, is that i have no flat, level surface to lay it on when welding it together. The concrete paving is uneven, the shed floor is uneven, everythings uneven!