Thread: Enclosed motorbike trailer build questions

Hi everyone

Just discovered the forum while I was looking for info on the trailer I am building. Great site with lots of info on all sorts of topics.

I’m looking to build an enclosed motorbike (and whatever else fits) trailer. I’ve sorted my basic design and just need to confirm some of the finer detail points before I get underway. It’s going to be tandem roller rocker axles running 14” rims with light truck tyres and will have internal wheel wells with a “pointy nose”, basic internal dimensions are 3000 long, 2000 wide and 1500 high. The nose will 800 long and 800 high and wide at the “point”. Total drawbar will be 1800 including the nose section. It will have a fold down rear door and lift up roof. I’ve bought a second hand axle/suspension set up with electric brakes on one axle and I’ve got some nice 14” HZ Statesman alloy rims which I'm going to fit with light truck tyres. I'm looking at a GVM of 2000kg

I’ve done a simple drawing of the base/floor of the trailer below. My thoughts were to make the drawbar (the green bits) in 100x50x4, the outside frame (black) in 75x50x3 and the framing (red) in 50x50x3. The pantec frame will be 25x25x2.5 or I might use 40x40x3 which will allow me to fit a roof mounted camper trailer tent set up in the future. Flooring will be 3mm aluminum chequer plate welded to the frame with 3mm (0.25 skin) aluminum composite cladding. I’ve also attached a picture of the basic design but it has slightly different dimensions. I’m getting a local trailer builder/welder to make the chassis/frame and I will do the lighting, cladding etc.

Am I on the right path?

The axles I bought are 50x50x5 RHS with 40mm square stubs welded in each end and are way too wide at 1760mm between previous spring mounting points. My question is regarding shorting the axles and the possibility of making an overlay axle.
- Could I cut the ends off and re weld the end piece of RHS on top the axle piece of RHS with an overlap of say 80-100mm (depending on space etc)
- Would it be better to weld a new stub axle on top of the RHS instead
- Or should I just scrap the RHS idea altogether and buy new axles?

That’s all for the moment but I’m sure there will be more

Depends what your funds are but I'd be more inclinded to get a couple of new axles. Also I think you may find that both axles will need to have brakes.

It was supposed to be a budget build, but with $1200 on wheels and tyres (5) and axles/suspension so far and another grand for cladding, say $500 for lights, cables, wiring etc and then there's the steel and fabrication cost

Only one axle has to be braked, although I am considering putting brakes on the other axle as well and for only $250 or so, I think it's cheap insurance.

Probably will go the new axles, generally about $100 each plus freight!!! Freight, the joy of living in the country

Looks like you are on the right track with your frame. I would not go 50x50x3 for that part of the frame in red, you could go back to 50x50x1.6 in my opinion, or even a 40x40x2 RHS. A lot of the weight and forces are taken on the main chassis and the drawbar.

I think your wall frames will be too heavy at 25x25x2.5. It is unneeded weight in my opinion.

If you go the roof top camper are you going to make all the walls from 40x40x3? I don't quite understand this bit. Would seem massive overkill if it was.

If it was me, and I did previously think of using a roof top camper on my trailer, I would make the walls from 25x25x1.6 (or 2), then probably 40x40x1.5 for the roof. If the roof did not need the camper, then I would use the same 25RHS on the roof.

With regards to the axles, I am not sure of the load rating of the setup you have with the RHS.

I found these guys on ebay the other day, their prices seem good:

Bawa Trailer Parts items - Get great deals on Couplings, Brake Kits items on eBay Stores!


And checkout my trailer build below. Its bigger than yours but uses the same ideas:

http://www.woodworkforums.com/f184/e...-build-133703/

Thanks surfin

I've already looked at your trailer and pinched some ideas

I thought the frame might be a bit heavy and will change to 50x50x2 and 25x25x2 which is not much heavier than 1.6 but somewhat stronger.

I'm not going to do the rooftop camper at this stage, I can always change the roof if I decide to convert it later on. The 40x40 frame was based upon the recommendation of a manufacturer.

I will change the axles, just to be safe and will order some 40mm square as soon as I work out my axle lengths.

Can I ask why you are going with tandem? If it will need to carry a lot of gear I guess it makes sense but if you want to keep it a little lighter you can go the single axle route on a trailer of that size. I just depends on what you want to put into it.

I've started my second trailer (I only need to carry about 300kgs so I'll keep it single axle unbraked). Mine will be 4000 x 2000 x 1500 (for the box).

One thing I am not sure about for this build is which sheeting to go with. I want to go with some aluminium panelling again, but in getting prices I've found some amazing ranges.
Perhaps (without hijacking your thread), it might be nice to discuss options here?

Here is what I've found so far:
* dibond $45 sqm for 3mm sheets.
* alucobond $65 sqm for 4mm sheets.
* Ullrich Aluminium "AL Composite" $28 sqm for 4mm sheets.

Having seen first hand what happens when the composite is cheap and nasty (delaminating after 12 months), I am leaning towards alucobond or dibond (apparently not rated for outside, but I have it on my current trailer for 12 months).

Does anyone else have some tips on long lasting composite sheeting?

I'm going with the tandem so I can get a 2 tonne rating and be able to carry some bigger loads. My last trailer was only a single and the loads sometimes got a bit much for it.

I've also found a great variation in composite panel prices. Some of the cheaper prices (for white panels) I've found are:
2400 x 1200 x 3mm sheets
- Mr Plywood $72
- Plastral (aluplus) $75 ($26/sqm)
- Acrylics Online $85

4000x1500x3mm
- Plastral $146 ($24/sqm)

I'll probably go the 4000mm panels as for my trailer it involves less cutting and therefore less pieces.

In your first post you mentioned welding the 3mm aluminium chequer-plate to the chassis. Were you intending to use transition inserts to do this?

Originally Posted by Dan-Da-Man

Can I ask why you are going with tandem? If it will need to carry a lot of gear I guess it makes sense but if you want to keep it a little lighter you can go the single axle route on a trailer of that size. I just depends on what you want to put into it.

**nearly spits coffee over monitor...**

He did say that he wanted a rating of 2000Kg, which is doable with single axle, but the wheel and tyre combination will be the biggest hurdle. Single axle hardware for 2000Kg is quite expensive compared to a similarly rated tandem setup. 12" Electric brakes require minimum 16" wheels (you may find a 15" rim that'll clear the drum...). and then getting tyres rated at over 1000Kg.

Originally Posted by bishboy

Hi everyone

Just discovered the forum while I was looking for info on the trailer I am building. Great site with lots of info on all sorts of topics.

I’m looking to build an enclosed motorbike (and whatever else fits) trailer. I’ve sorted my basic design and just need to confirm some of the finer detail points before I get underway. It’s going to be tandem roller rocker axles running 14” rims with light truck tyres and will have internal wheel wells with a “pointy nose”, basic internal dimensions are 3000 long, 2000 wide and 1500 high. The nose will 800 long and 800 high and wide at the “point”. Total drawbar will be 1800 including the nose section. It will have a fold down rear door and lift up roof. I’ve bought a second hand axle/suspension set up with electric brakes on one axle and I’ve got some nice 14” HZ Statesman alloy rims which I'm going to fit with light truck tyres. I'm looking at a GVM of 2000kg

I’ve done a simple drawing of the base/floor of the trailer below. My thoughts were to make the drawbar (the green bits) in 100x50x4, the outside frame (black) in 75x50x3 and the framing (red) in 50x50x3. The pantec frame will be 25x25x2.5 or I might use 40x40x3 which will allow me to fit a roof mounted camper trailer tent set up in the future. Flooring will be 3mm aluminum chequer plate welded to the frame with 3mm (0.25 skin) aluminum composite cladding. I’ve also attached a picture of the basic design but it has slightly different dimensions. I’m getting a local trailer builder/welder to make the chassis/frame and I will do the lighting, cladding etc.

Am I on the right path?

The axles I bought are 50x50x5 RHS with 40mm square stubs welded in each end and are way too wide at 1760mm between previous spring mounting points. My question is regarding shorting the axles and the possibility of making an overlay axle.
- Could I cut the ends off and re weld the end piece of RHS on top the axle piece of RHS with an overlap of say 80-100mm (depending on space etc)
- Would it be better to weld a new stub axle on top of the RHS instead
- Or should I just scrap the RHS idea altogether and buy new axles?

That’s all for the moment but I’m sure there will be more

Welcome aboard Bishboy.

My suggestion would be to keep the brakes and hubs, and just order a pair of axle beams with the electric mounts fitted. My concerns with axles made up with stubs welded into SHS are a: whether they're straight, b: what wall thickness is the SHS, and c: how far do the stubs go back in the SHS? This is always a gamble when buying second hand axles, particularly ones fabricated this way.

40mm stubs will generally have 'LM' (Holden inner & outer) bearing pattern, which will only give you 2000Kg TOPS!! But if you get new beams, then you can get a price comparison on 'Composite' (2400Kg) or 'Slimline' (2800Kg) axles to give you that little safety margin. Composite axles are used quite a bit on Caravans and have a Falcon outer bearing and Holden inner bearing. If they're machined on 40mm axles, they're rated to 1100Kg each, and on 45mm axles, they're rated to 1200Kg ea. A 40mm Composite axle shouldn't cost you any more than an 'LM' axle as it's the same material stock, and the same time frame in a CNC.

Glad to see you're going 100 x 50 x 4mm RHS for the drawbar.

Remember... Even with the nose cone, the rule of thumb for axle placement is still 1/2" rear ward of centre for every foot of body, but Don't include the nose cone! I had one customer build an enclosed GoKart trailer with the nose cone included in the measurement, and wondered why it kept wanting to swap ends with him on the road, and he was a manufacturer selling them to the public!!

Normally a camper would not weigh any more than 100Kg, that includes the base for the bed.

Of course this weight is distributed over a large area, so u dont need to go too crazy wrt supporting the roof. 40 x 40 x 1.6 (2.0 mm max)would well and truely cover it. Any more and its just extra weight for no real benefit.

Thanks for the info guys.

Frame will be:
Drawbar: 100x50x4
Main frame: 75x50x3 (this will include base of nose cone)
Frame bracing: 50x50x2
Pantec frame: 25x25x2
If I decided later to get a roof top camper, I'll just make a new roof as I'll have to replace the aluminium composite with plate anyway.

Axle wise I've pretty much decided on 45mm round with SL bearings, which have a rating of 1500kg each (14" wheels) and will allow me to increase the GVM of the trailer later if I put brakes on the second axle (probably won't but you never know). Or may use some drop axles, also 1500kg each, but $100 extra for each axle.

As the rectangle part of the trailer is 9'10" (lets say 10"), the centre hanger should therefore be 5" rear ward of the centre??

For the floor, if I use alloy chequer I won't go to the hassle of welding it, just rivet/screw/bolt it to the floor. If I go steel I'll weld it. It will come down to a weight vs $ decision. Aluminium 3 sheets for say $450 at 75kg or steel $270 at 150kg ?? If I go steel, then I could use the difference to buy drop axles??

Also on the cost vs weight issue, the composite panels cost about $200 more + freight than colourbond and all up weigh about 30kg. Is it worth the extra cost and hassle fitting to use the composite panels??

Also, what is the best way to seal the rear ramp, roof and side door? Is that adhesive foam strip the easiest? For the ramp and door, do I have a piece of flat steel welded to the trailer frame so that the door and ramp frame can seal against it? Or do I go to the hassle of refridgerated truck seals as in the picture in my first post??

Are T handles for the rear ramp and side door the easiest ?

Told you there would be some more questions

Still more:

• hinges - over the seal style hinges as per photo above and piano hinge at the roof hinge point?
• gas struts for the roof - what length and shaft size?

Originally Posted by bishboy

T
For the floor, if I use alloy chequer I won't go to the hassle of welding it, just rivet/screw/bolt it to the floor.

Good idea, you cannot successfully weld aluminium directly to steel without special processes

(Fronius USA LLC - Focus on welding - Basics of welding technology)
(Can I Weld Aluminum to Steel?)

Originally Posted by bishboy

Thanks for the info guys.

Axle wise I've pretty much decided on 45mm round with SL bearings, which have a rating of 1500kg each (14" wheels) and will allow me to increase the GVM of the trailer later if I put brakes on the second axle (probably won't but you never know). Or may use some drop axles, also 1500kg each, but $100 extra for each axle.

The following ratings are based on an axle made from solid S1045 Duraflex. A 45mm Slimline axle is only rated to 1400Kg, not 1500. Even a Slimline on a 50mm will only get you 1450Kg. You need a "Parallel" axle (the slimline inner bearing is used as both inner and outer) to get 1500Kg on an axle. If you're not carrying anywhere near that sort of weight, then it really only effects the axle load numbers you put on your VIN plate, which will be 2800Kg.

Originally Posted by bishboy

As the rectangle part of the trailer is 9'10" (lets say 10'), the centre hanger should therefore be 5" rearward of the centre??

Correct!!
However... this is a recommended rule of thumb for an empty trailer. If the trailer is being used to regularly carry a particular load, and that load is heavier at the rear (think of say, a twin engine outboard), then the wheels of that trailer need to be placed further back than normal.

Originally Posted by bishboy

For the floor, if I use alloy chequer I won't go to the hassle of welding it, just rivet/screw/bolt it to the floor. If I go steel I'll weld it. It will come down to a weight vs $ decision. Aluminium 3 sheets for say $450 at 75kg or steel $270 at 150kg ?? If I go steel, then I could use the difference to buy drop axles??

Also on the cost vs weight issue, the composite panels cost about $200 more + freight than colourbond and all up weigh about 30kg. Is it worth the extra cost and hassle fitting to use the composite panels??

Also, what is the best way to seal the rear ramp, roof and side door? Is that adhesive foam strip the easiest? For the ramp and door, do I have a piece of flat steel welded to the trailer frame so that the door and ramp frame can seal against it? Or do I go to the hassle of refridgerated truck seals as in the picture in my first post??

Think about what you're putting in the trailer, and what the trailer is being made from... None of which require a completely sealed, waterproof environment. Adhesive foam tape would be the easiest, or pinchweld with a rubber seal would give you longevity, but a little more complicated to setup. A drip rail above each door opening will help stop roof runoff as well. Those refridgerated seals look great, but I can imagine them being cheap...

Are T handles for the rear ramp and side door the easiest ?

Folding T-handles are quite neat, and also have the facility to have a tongue where the handle is, as well as rods that lock the outer corners of the door too.

Told you there would be some more questions

Still more:

• hinges - over the seal style hinges as per photo above and piano hinge at the roof hinge point?
• gas struts for the roof - what length and shaft size?

These all depend on the weight of the roof, and the position of the gas strut. I have a fitment guide for struts, but only for vertical doors that open up to horizontal.

Not sure on hinges...

Hope this helps.
Yonnee.

Originally Posted by bishboy

For the floor, if I use alloy chequer I won't go to the hassle of welding it, just rivet/screw/bolt it to the floor. If I go steel I'll weld it. It will come down to a weight vs $ decision. Aluminium 3 sheets for say $450 at 75kg or steel $270 at 150kg ?? If I go steel, then I could use the difference to buy drop axles??

Also on the cost vs weight issue, the composite panels cost about $200 more + freight than colourbond and all up weigh about 30kg. Is it worth the extra cost and hassle fitting to use the composite panels??

Also, what is the best way to seal the rear ramp, roof and side door? Is that adhesive foam strip the easiest? For the ramp and door, do I have a piece of flat steel welded to the trailer frame so that the door and ramp frame can seal against it? Or do I go to the hassle of refridgerated truck seals as in the picture in my first post??

Are T handles for the rear ramp and side door the easiest ?

Told you there would be some more questions

Still more:

• hinges - over the seal style hinges as per photo above and piano hinge at the roof hinge point?
• gas struts for the roof - what length and shaft size?

For my trailer, I used marine ply on the floor and it worked out well. Screwed it down using long tek screws. Probably a lot cheaper than either steel or alloy checker plate, and not a real lot heavier either. Used some of those folding D ring things for the tie downs to hook onto. Another benefit of ply is its not cold on the feet in winter.

I used a product similar to Alupanel for the walls. I used glue similar to Sikaflex that I had used on a previous trailer build, to glue the panels on. Well they lasted 2 trips and the panels were coming off (even though the other trailer wouldn't come apart in a nuclear explosion). So ended up rivetting it on. So do your homework as to how you will afix it. I would also recommend cladding the insides with mesh. This not only gives you something to hook things on, but it protects the outer layer. Don't get the real fine mesh otherwise the tie down hooks etc won't fit in.

To seal the side door, rear ramp and roof I used a high density rubber from Clarke Rubber. Probably be 5mm thick. Comes on a roll. The fact it is high density means it doesn't squash much, but still helps seal well. So what this means is, if you want the side door, rear door etc to be flush with the walls, you need to make an allowance for the rubber when you attach the bit it will close against. So the piece of flat steel welded on the inside needs to be spaced away to accomodate the seal. Make sense?

For the roof seal, I made sure the seal was attached to the top of the wall frame, rather than the bottom of the roof. And try and get it to be as continuous as possible all the way around to prevent water from coming in. If you can't make it continuous fill gaps with silicon. I originally had the seal attached to the bottom of the roof, and there might have been a slight bow somewhere, so water would enter in the little gap when the trailer was sitting still. But when its the other way around, the rubber is like a little wall, that helps stop water ingress. Make sense also?

I used a T handle on the side door...works great. The rear ramp I used those toggle latch things like you find on aluminium utes. Rear door I used the weld on hinges that have a grease nipple also. Worked well.

Finally the gas struts. Hopefully you have a place near you that sells them. They will ask you certain measurements and weights of the roof at a certain angle, then they can make struts to suit .

Hope that helps a bit.

Cheers