Thread: Noob alert ! Box trailer questions - terminology

Hey Ross, and Welcome aboard!!

Originally Posted by RossAus

Hi Guys,

I love the forums. Sooooo much useful and informative information, and to top it off, it's not expert jargon, so a layman like myself can understand most of it. Oh, and I love that people are able to ask really basic questions and I haven't seen anyone get flamed for it yet !
No such thing a a stupid question. The stupid part is NOT asking it and making simple errors.

So, that brings me to my turn.

I'm embarking on a box trailer build soon - because I need one, but I also want the satisfaction of making it myself. It will be an under 750kg one...no brakes...nothing flash....about 7.5 x 4-ish (reading Yonnee's build I saw that width was determined by axle length - good idea).

Sometimes... the cost saving on your axle can be outweighed by all your wasted offcuts by not making the trailer to standard sheet sizes. Also, your wheel and tyre choice will effect the axle length too.

The only thing I am now stuck on is the running gear and coupling.

I'm in Sydney, so if anyone knows a good supplier of axles, hubs, and couplings etc that will treat me with respect, that would be good.

BUT, what I'd like to know, is what I actually need and the right terminology.

* 5 leaf slipper springs with hangers and whatever the other end is called?
"Rear Slipper Hanger"
If you buy a spring set, you should get everything you need without having to ask for individual items.

* a 39-45mm solid axle, or will stubs be okay ? If using stubs, I need to find a round steel tube that just fits over the stub and is welded.

Depends on the confidence you have in your welding, and how much you want to stuff around making your own axle. If you live far from the supplier, and haven't determined what width the trailer will be, then stubs can be handy, but for the mucking around, I would prefer a solid beam nearly every time. As for size of material, this is determined by the weight you realistically think you'll carry.

• **Material**-*Inner*-*Outer*-(common name)-*capacity*
• 39mm round - Holden/Holden (LM) bearings - 750Kg
• 40mm square - Holden/Holden (LM) bearings - 1000Kg
• 40mm square - Holden/Ford (Composite) bearings - 1100Kg
• 45mm square - Holden/Ford (Composite) bearings - 1300Kg
• 45mm square - Ford/Ford (Slimline) bearings - 1400Kg

* bearings?
Yes, you'll need bearings.
* hubs (or do bearings and hubs come together?)
Both!
"Lazy hubs" can be bought separately to bearings or as a package. The bearings are determined by the axle, which is in turn determined by the weight capacity.
(See above)...

With the coupling, what is a standard coupling called? "a Coupling".
They come as 2-bolt, 3-bolt and 4-bolt. It's the braked couplings that have different names.
...and do the plates come with them? I think they do. Not usually. Some fabricate their own, but that's a pain in the neck. How sharp's your 1/2 drill bit?
Will a 2-hole coupling-plate be okay? I prefer 3-bolt, but that's me.


I've been loking online, and most suppliers seem to be in VIC or QLD - what, no trailer spares needed in NSW?

Al-Ko have a branch in Sydney... haven't been at Al-Ko for over a decade, so I don't know how friendly they are, but it's a start.

Many thanks Yonnee, you have certainly given me a good start. I also remember in a thread you made reference to checking with manufacturers for incorrectly built axle set ups that may be going cheap, so I'll do that too.

Realistically, I'd expect under 750kg loaded weight - though it may need to take 2 road bikes ~ 200kg each - that would leave only 350kg for the trailer. From some basic calculations, I believe that is more than possible for what I ma building.

EDIT: AL-KO distribute through Trailer City http://www.trailercity.com.au/ who are only about 15 minutes from me. I might try to pop in tomorrow morning and see what I can find.

Oh, and it looks like I need to get my wheels and tyres first too in order to work out the tyre width and rim to tyre offset which all then has an impact on axle length and/or chassis width.

I'm just going to find some standard commodore rims (I have a late model Commo currently) and get some standard tyres put on.

Originally Posted by RossAus

Oh, and it looks like I need to get my wheels and tyres first too in order to work out the tyre width and rim to tyre offset which all then has an impact on axle length and/or chassis width.

I'm just going to find some standard commodore rims (I have a late model Commo currently) and get some standard tyres put on.

Not necessarily. If you've decided to go Commodore, then you just need to determine the actual trailer width. All Commodore rims are pretty much the same stud pattern and offset, so you can fairly safely order the axle 18" longer than the chassis width. Personally, I would go with early Commodore 14" or 15", VB-VZ, as tyres for these are much cheaper. Also, once you go 16x7's, 215 tyres are a tight squeeze under a standard trailer guard.

I would go with early Commodore 14" or 15"

I run 15" Commodore on the tandem. I recon its easier to get tyres than with 14's.

Ideally would like to be able to run 16's (being the current base model standard rim) but I wouldnt have the clearance as Yonnee says.

Thanks guys. My 'late model' commodore is actually a VZ ... 5yrs old now ... but with my history of cars, that is very late model

so if my chassis is 4.5' (54") wide on the outside, I would be safe getting a 72" axle ? This would give 9" on ech side. How much of a gap does this leave between the inside tyre wall and the chassis?

If you ran 14" rims with 185 tyres, then roughly 40mm, If you got 15's with 205 tyres, then the clearance reduces to around 30mm.

Bear in mind though, a single axle trailer doesn't have a great deal of suspension movement or sideways tyre flex, so 30mm will still be fine.

Thanks for that info ! I'll see what my car's current rims and tyres are, and probably just plan with the same. In fact, I might even be putting mags on the commo, and can then use the current rims for the trailer. We'll see.

Hi i found a web site www.activefabrications.com.au/
unfortunatly they are near Brisbane but if you have your wheels they can make an axile any lenghth you want