Newbie Trailer Design Help

[dales133]

Yep it's alot more thinking than I planned on too! And research and plan changes....

[Strop]

Well I pulled the calculator out today and tried to figure out an end weight for my plan. It came to 586kg (1300 lbs). That is with everything I could think of and perhaps dream of.

The half flexitime axles relevant to me are rated at 600kg and the next ones up are for 750kg-1000kg. I am thinking that 600kg is too close and that I should take the next level up.

Is that correct thinking?

[dales133]

Yea I'd go 750 minimum.
You'll always end up with more weight or stuff than you planed

[Strop]

My 586kg was full of water, clothes, tents, fridges, food, solar panels, battery and the kitchen sink.

The problem, from my reading of the flexiride specs, is that the tank will now NOT fit across giving me the ability to balance that water.

Back to thinking again.

[pchast]

I question whether you need to add the weight of yourself and friend
too or is it just 'rolling' weight that needs to be considered?????

[Strop]

I would have thought only your travelling weight because that is when the suspension is working. Not enough and the trailer bottoms out and transfers hard jars to the body. Too much and the suspension doesn't work properly and the trailer will bounce or skip along. If you are stopped and inside bottoming the suspension out shouldn't have any impact as the energy transfer is not harsh like hitting a pot hole while driving along. The suspension in the trailer that is important when stopped is the mattress.

But, I have been known to be wrong...........often.

Laurie

[Strop]

I have been still planning away. If I gave the following diagram to my trailer builder is it sufficient for him to order my axle?

Screen Shot 2014-11-01 at 12.41.28 pm.png (79.7 KiB) Viewed 873 times

So there are a few questions the design raised. I have been aiming at having my galley bench at the same height as a normal kitchen bench - 900 mm. At the moment with everything in the design I am at 996 mm if I use 205/60/r15 tyres and 982mm if I use 185/60/r15 tyres. That is a measurement without compression of the springs or the tyres. It will be a 750kg spring rating and the trailer weight when completed and loaded is 570kg.

I can't lower my bench top because it has been designed for a specific 12v fridge.

So how much compression do you think I will get? I was thinking about 10-20mm overall.

Any advice on tyre selection?
Any advice on anything?

thanks

Laurie

[dales133]

What fridge are you using?
Sounds pretty high on those tyres

[Strop]

Waeco 40 Litre with a slide underneath. Might have to drop back to a 35 litre.

Or find someone that has 50mm x 50mm steel in 3mm. That gives me 25 mm back. Only planning on using 12mm for the floor as well so nothing to cut back there.

Might revisit those measurements. Might be able to reduce my air space.

Laurie

[Strop]

Waeco CF40 580mm long - 445mm high
Heavy duty slide 600 mm long Extends out 620 mm - Bracket 19mm high fit 12 mm shelf - total height 31mm
25mm air gap on top

Allows me another 41mm back. If I am game enough to go to a 15mm air gap on top I have 50mm back. I am only using a 15mm gap on sides.

Problem with Waeco CF40 is that the motor is at the back, but I have a solution for that by having an opening at back across to open space in galley. Sacrifice 50mm - 100mm of drawer space to create a vent.

Takes me back to 946 mm if I use 205/60/r15 tyres and 932mm if I use 185/60/r15 tyres. With compression almost there with 185 tyres but would prefer 205's.

With a slide taking that much weight not sure if 12mm ply is sufficient so would have to drill through and put large washers under trailer to take weight.

I could put up with 946mm I think. Compression of 10mm - 936mm Compression of 20mm - 926mm?

Amazing the flow on when you look at things.

[Strop]

Just came to conclusion looking for new trailer builder. Must use 50 x 50 mm square tubing. Lighter weight and gets me down to 900mm bench height. Now where to go

[KCStudly]

Glad to see you doing so much detailed planning. It should pay off while you build by running into less problems. There will be enough of those as it is, so the more you can figure out now, the less problems you will have. At least that is how I look at it.

On the specifics, I think you are going to want to leave more clearance between the tires and side walls. 7mm is not enough for a sprung axle (...and would be too close even for a torsion axle, IMO). I would look for at least 19mm (3/4 inch) per side

Also, with a drop spindle axle you will want to take a close look at the clearance between the back of the spindle forging (or drop plate gusset) and the outside of your wall and frame. I misjudged this on my low deck tandem axle car trailer and ended up having to notch the outsides of the main tubes; boxing in all 4 notch cuts; then reinforcing the main tubes with heavy fish plates on the inside.

[dales133]

Supergal comes in 50 X 3 I'm pretty sure.
Duragal (only coated on the inside) I think maxes out at 2mm.

[Sheddie]

http://scottmetals.com.au/rhsgalv.php
Look at this site.
Frank.

[Sheddie]

Hi Laurie,
I have been having another read of this and have a few questions/comments.
Bench height, when we had the kitchen done for our house we went with 950 bench height. It is much easier on your beck at this height and we really notice how low everyone else's benches are now.
KC' comments re the clearance between tyres and walls, I have to agree with him on that one.
Re the no spare wheel idea, we have done over 10,000kms with our TD with some goop and a pump in the tongue box and so far have not had to use them. As a former tyre shop owner, I have always felt uneasy with the situation, having seen the condition of some of the trailer tyres that people came to me with. And we were glad we had a spare under our old caravan when travelling in the South Island a few years ago and the tread paled off one of the tyres. We recently acquired a space saver spare that I will sling up underneath, just behind the axle.
You say you want 15" wheels. Any particular Reason? Same with 205 width Tyres?
If you are planning on hanging your spare underneath and right at the back, with the likes of a 205 (a bit over 200mm) below floor height, you will need to check what clearance you will have on crossings, speed humps etc.
One option you do have to save having to carry a spare is to use a similar size and the same stud pattern as your tow vehicle. But as you are planning on towing with a few different vehicles, this may not be possible.
I hope this has helped confuse things.
Frank.