Box trailer build, alu or steel welds?

[ddan1275]

I'm going to build a box trailer similar to a tow a van shape but to suit my needs for motorsport but would like some advice on materials and welding. I need it to be as light as possible to be able to push it up a drive.

The spec will be 3.5m (11.5ft) long in total including the hitch, 1.5m (5ft) wide with with wheels outside of that. 1.5m high and a loading area of 1.5 x 3m ( 5 x 10ft) including the pointed front.

The initial plan is to make a box base frame from aluminium 50x25x3.2mm then make the uprights and roof frame from 30x30x3.2mm angle.

This will be laid onto a frame that the tow coupling, suspension units and mounting plates will all be welded or fastened to. I'm not sure if this shall be an 'A' frame shape or more of a T shape using the axle as the top of the 'T'

Because weight saving is very important I initially wanted to make the frame also from Aluminium but I was told that it will be prone to cracking welds bouncing around on indespension units. I would be better to make it from steel and then bolt the box frame on top of it. Is this true, and how strong is an alu weld compared with steel?

Has anyone done a self build?

 

[bigegg]

Id go with a steel frame.
Ali isnt suitable for a chassis without heat treatment, and tbh youd save more weight per £ by using lighter sheet materials.
Or buy a remote control "tug" to drag it up the drive.

You are aware that a "new build"trailer needsvehicle approvsl (£££) before it canbe used on uk/eu roads? Without it, your insurance will be invalid.

 

[rtbcomp]

My insurance company (Saga) excluded home-built trailers altogether.

 

[ddan1275]

I had heard a few things but didn't know if they were in place or not. can i borrow one of a redundant genuine trailer and play dumb?
I read a while back about it costing 5k to have a design approved but you could submit a plan and have a one off done for £75?

Thanks for the reply. the sheets im using are going to be very light, same as what sign companies use. Even with alu and the suspension wheels etc it adds upto approx 160kg which is fine but my 360kg one is much to heavy to push into the garage to pre load up

 

[BrokenBiker]

my current insurer want specs off the trailer data plate before allowing its use.

It will ha e to be subject to test and everything will be scrutinised.

I would go with steel frame and wooden floor and just learn to reverse it up the drive

 

[blenkie1]

Would you not be better buying a cheapish 2nd hand trailer/car transporter and putting an enclosure onto it. Would that satisfy insurance

 

[outofthefire]

If you still want to build it i'd use channel rather than box and bolt it together rather than welding whether its steel or ally. If you mix steel and ally you need something to go between them to stop galvanic corrosion. When we build ally wagons we use hardwood between the ally runners and the steel chassis, between ally bearers and steel cleats we use double sided foam sticky tape.

 

[outofthefire]

Personally i'd buy a caravan and cut the back out of it and replace it with a door/ramp.

 

[bigegg]

Personally i'd buy a caravan and cut the back out of it and replace it with a door/ramp.

Caravan chasses need a LOT of bracing to take any sort of weight.
I tried to use one to run waste books to the recycling plant - carrying two pallet sized tubs of about 180kgs each - on an unbraced caravan base.
First run, it didnt get off the industrial estate before it bent.

 

[ddan1275]

Thanks for the replies, i considered all the options of adding to existing trailers etc but it just works out easier building a new one from scratch. I have a narrow road with cars on and reversing on isn't possible without some of the cars being absent.

OUTOFTHEFIRE why do you suggest channel over rectangular box section? would it not be weaker having only three sides instead of four?

I wanted the top half from alloy because it's much easier to drill for the panels that fit inside. I was going to use plastic damp course held by silicone to separate the steel and alloy fixing positions

 

[CornishPete]

my ifor trailer is all channel. Its probably for a few reasons, less messing about compared with box section for galvanising purposes and less likely to trap water when in use too. Also the suspension is bolted to the trailer not welded. I guess channel is better for this too as to bolt to box you have the void in-between to deal with. The torque on mine would surely distort the box over time and loosen? Depends on wall thickness I suppose.

 

[W.olly]

I mite of missed the new reg on trailer regs, but how do they know how old the trailer is? if it was built 5 years ago even longer, then do the new regs still stand. if so there will be hundreds if not millions of trailers illegally on the road. could be a fully refurbed trailer.

 

[ddan1275]

When you say sleeve the bolts, are you meaning drill a larger hole in the box and fit a sleeved tube right through that the bolt will slide inside? I agree it would be much easier to get at any bolts from inside the channel.
I had a motorbike trailer a few years back from a mixture of 5mm thick angle and box but angle will flex even more than box. A thicker channel sounds a good option then for the chassis.

 

[W.olly]

Re: sleeve, yes.

Well, larger hole in one wall so the bolt is effectively gripping the other wall.

As for age of trailer - most new parts are stamped with a production date

so when do the regs start from. i dont get it, if a trailer that needs new rails but good suspension, so maybe just replace some of the chassis....how is that worked out. they cant, can they. if so all old trailers from a certain will be no good.

 

[brightspark]

so when do the regs start from. i dont get it, if a trailer that needs new rails but good suspension, so maybe just replace some of the chassis....how is that worked out. they cant, can they. if so all old trailers from a certain will be no good.

so u have rebuilt the trailer with new parts. ive just put new indies and hubs on mine but trailer is 40 years old

 

[W.olly]

Thats is how i see it pdg, but this will take years, there are so many DIY trailers on the road, also trailr that are commercial that have now lost plates. Its going o be difficult for them and take a long time to get to what tey want.

I could build a trailer next month and they could not do anything tp prove how old it is or what has been changed.

 

[colnerov]

As for age of trailer - most new parts are stamped with a production date

As should the chassis. I think it's not retrospective on older trailers.

This was all introduced a few years ago because as pdg says they wanted all trailers to be registered because they were going to have them MOT tested but it was delayed due to unspecified difficulties. This was told to me by an MOT tester who was on a regional committee that discussed it.

Colin

Edit: One benefit of this has been that it has cleared a lot of shonky trailers off the road, When was the last time you saw a trailer built on a mini subframe?

 

[brightspark]

mind u when u see the state of some trailers there's little wonder they want things sorting

 

[Hitch]

mind u when u see the state of some trailers there's little wonder they want things sorting

Someone towed(!) one into use only a few weeks ago, with a rusted/snapped axle, the broken bit held to the trailer - i use the term loosely! with a g clamp.

Previously had one in to have a bit of ally chequer cut and folded for the bottom and front. Was a slightly tight fit, so i stamped on the corner to push it down, and the side of the trailer snapped off

Junk like that shouldn't be on the road. They are stopping you quicker than it seems, as rtb mentioned, theres a good chance your insurance may not like a non type approved trailer. In which case pulling a home made bit of scrap caravan will make you insurance void.

 

[brightspark]

I saw one that was made of chipboard and just bits of dexion up the sides units were bolted to the wood