Off road camper build

[Flaps]

Hey everyone im building a camper trailer going up north next year to karijini and do a coast run. Alot of people have be putting doubts into my head about whether or not my camper is going to work or not they havent told me why but if there are any smart people out there can tell me there opinion that would be good. http://myswag.org/forum/index.php'topic=24034.0

Cheers

[roverrescue]

Flaps
First up I dont build offorad box trailers with tents - I do the offroad boat trailer thing!
But I have played a fair bit with things dragged behind 4x4 a bit and will make a few comments!

First up - your frame seems pretty solid
You could have saved some weight going to a lighter section but it certainly fits in with the "if in doubt beef it out" motto of most backyard engineers!!

Second - In its current state Im not in love with your hitch setup
You have used 100x50xstupid thick chassis rails resisting the killer force on all single axle trailers (ie verticle dynamic loads) and compromised that strength with some 10mm or whatever flatplate - At the very least run some gussets (call them sliders) of flatbar on edge along the underside of the hitch plate and along the a-frame 300mm or so - This is to transfer the verticle loads from the hitch into the Aframe

Third (and this one is a soft spot for me as I have been here before) is your swing arms!
-65SHS5 would have been my choice but irrespective of that
-The location of the spring mount (fulcrum) vs the contact of the tyre vs the chassis attachments is gonna lead to some super funky camber / bush loadings / tyre scrubbings / poor load control
-Sure go with it for now but WHEN not IF it annoys you - Cut up the swing arms and make a stepped axle then mount four links ; 2 outer chassis rails to underside of axle straight links then 2 inner chassis to upper stepped surface of axle triangulated links
-I also have slight fears for the strength of your stub axle flange (compare it to the flange used by LR or Toyota)

In honesty - the whole independent suspension thing is wayyyyyyyyyyy overdone by the trailer industry
On a single axle trailer you will never garner the benefits of independent suspension but will have to compensate for all the negatives (varying geometry with load and suspension height & non cross axle load sharing to name the most significant)

You know that now is the time to make changes to your build which makes you smarter than me - I just kept building junk and hating it till I learnt the lessons above ;)

Steve

[Flaps]

Man what u just said about the swing arms is very hard to understand u couldn't explain it any better could u. i was going to add a gusset under the hitch point but thought it would be strong enough but might just do it anyway its always better to over engineer.

cheers

[Flaps]

That there is sorta what iv copied. Cruisemaster® Independent Coil Suspension (http://www.vehiclecomponents.com.au/products/cruisemaster/cruisemaster-coil)

[Slunnie]

Looks cool. :cool:

the things I would look at:

Xmembers and outriggers - I never let the kids run Xmembers and outriggers into the chassis rail at different heights. When the trailer flexs it works the sidewalls of the chassis rails and they crack around the welds. We tend to run the same depth for the Xmembers and the main rails, but run the Xmembers in a lighter or narrower section. You've done it now, but perhaps looking at running corners of RHS between the rails to bring the forces from the sidewalls back in to the top and bottom plates of the main rails which is where the strength is in that plane.

Axle mounts. These look well braced, but I would run a flange around the plates that bolt together on both plates again to prevent flex at the corners of the plate and latter on fatigue cracking.

The upper spring perch - same, flange to prevent the plate from flexing and fatigue cracking all over it.

Front Xmember. For an offroad trailer, I'm not sure if a 50x50 Xmember will be strong enough. A great section drawbar by the looks of it, but the main load that goes through the draw bar is levered off the front Xmember. I'm not sure what section the draw bar is, 100x50? and if thats the case, the draw bar might be somewhere around 4x stronger than the Xmember (but the Xmember is loaded in a stronger way than the drawbar).

Front coupling plate. I would look at running that 10mm plate between the drawbar rails and mounting the coupling between the drawbar rails with the handle and ball receiver protruding. It will be a much stronger and fatique resistant setup if you want the coupling down low.


BTW, I still think it's cool. :D

[Flaps]

Cheers man its good to get some feed back i am going to weld the axles in with a gusset once i get the wheels on then use some sort of caster correction to correct any toe in or camber. Like danny did his idea is good

[roverrescue]

Great tips on bracing and hitch mount Simon - I hadnt noticed the 50SHS cross member

Flaps I assumed the frame was not completed and gusetting was still to come

With regards to the swing arms - have a look at that cruisemaster setup
The bottom spring perch is located outside the outer suspension link

On yours the spring is well inside (I did this once too!!! my geometry was almost exactly the same as yours)
What this means is the camber load on your setup has the coil as the fulcrum and will lever between you chassis links
Camber will be very hard to control with the spring this far inboard

When I did essentially the same geometry as you I actually aimed for about 2 degrees of positive camber at ride height (I wanted 0 but figured it would load up so +2 would allow it to load back to 0) - but when loaded and driven it pulled down to nearly 4 degrees negative camber - This means flex in links and bushes was allowing 6 degrees of camber (thats a lot of load in what seems a "rigid" setup) So even though it looked okay (for a racing trailer) it scrubbed tyres - so a few trips later I changed it

I think there will be too much leverage and camber in your current geometry
All my rambling in the last post was that I modded my setup to a solid axle with "triangulated 4 link" search on google or look under a 200series rear axle to get the concept

The benefits beside fixed camber and castor were astounding
I was able to drop the spring rate as there was a measure of cross axle load sharing (you could do this with an anti roll bar)
The trailer was more stable at speed
The suspension worked just as well

Anyways I clearly need another coffee as I am now rambling!
Please dont get me wrong - I love that you are building and it looks very tidy
Just trying to save you the time of rebuilding it ;)

Steve

[Pedro_The_Swift]

both suspensions taken to the extreme-
http://a7.sphotos.ak.fbcdn.net/hphotos-ak-snc7/385420_543970032299327_732039539_n.jpg

note the wheels on the buggy are exactly upright at full droop
and again, at full compression
https://www.aulro.com/afvb/images/imported/2012/08/1289.jpg

Flaps, these guys make it happen for exactly the same reasons as you,,,

[roverrescue]

Upper and lower links though Pedro - only way to control the wheels like that.
Or is that your point?

If I was to build another independent design on a trailer (but i wouldnt ;))
I would run upper and lower links - it really is the only way to control camber and caster

S

[justinc]

There is nothing wrong with the correct leaf suspension pack, good quality correctly valved shocks and a decent all terrain hitch, (which incidentally is where MOST of the articulation happens), most obviously in single axle configuration.

Tandem axle, well load sharing leaf suspension is OK, but independent coil would probably be better in that application IMO, but I have little experience in THAT department though..

My CT built by Cape York Trailers in Cairns uses Hilux rear leaf packs, hilux rear shocks, and BIG Alko 6 stud hubs and electric brakes. Rides very well and soooo much more simpler than multiple links and bushes etc etc.

IF you were to damage a lower link, irrepairably, how would you go with 'spares'? Do you have the ability to fit bushes etc on the track? Can you buy shocks off the shelf anywhere? what about landy stud pattern extra rim availability?

These are all the questions I asked myself when looking at options many years back, and settled on our current set up for all the above reasons. EG If I want a spring bush, spring pack, spare rim, rear shock, there are plenty of rolled Hiluxes out there conveniently already on their back waiting for me to relieve them of their rear suspension components...:twisted:

(BTW, you're doing great work, I just added my thoughts, as I think they are important to consider RE spares availability and ease of repairs should you need to.)

JC:)

[roverrescue]

JC,
You make a good point

78 series rear springs setup well, ride as smoothly as coils! Honestly! (But they will be reliant on dampesrs like coils)
and light years betterer than 75s or Hilux rears.
I have built using all three - these days for simple leaf setup 78s would be my only choice. 78 springs packs are ummm quite long though and pose a few packaging challenges, they are nearly twice as long as your standard wheel arch! But still the best choice for a leafer job.

And besides rolled 78s are just as easy to find as luxes ;) But we both know that you wont break a factory tojo leaf pack on a trailer...

78 leafs would probably cost more than a linked coil setup. Dampers are the same, even if you got spring packs or coils for nothing - in a link setup you need some tube and a few bushes... for leafs you need shackles, front and rear chassis mounts, fishplates & Ubolts that match your axle - these add up.

But coils are sexier than leafs and that really is the defining factor!
Im in the planning stages of building the chassis for a mates box/camper trailer.
I have argued that 78 leafs will do the job as well and more simply but he wants coils so 4link it is.

S

[Flaps]

I used the old springs off my defender thats why they are so fat and long and the reason for me running them up inside the chassis. i see what ur saying the spring really need to be mounted on the other side of the 100 x 50. i think if i did that i would need shorter springs. The bushes i have in there are pre packed ones so i hope they give less play. But as soon as i get tyres on it i will check camber with and without wieght to see if the bushes are giving to much.

[roverrescue]

Youll get both bush flex as well as twist in the 50SHS
Probably not as noticeable with static weight but load her up and flog it along a rough road for a few kays then re-measure the camber

I used LR coiler springs on the trailer I speak of
The fronts were a better match for the tight geometry of a trailer and I set them to run with a compressed height of 300mm from memory

Limit your travel to 100mm up and 100mm down
A trailer will never use any more travel than that and 100mm of up travel is ample for taking the bigger hits

S

[POD]

The build quality looks great- I love the jig bench, great way to keep things matched. Personally I think independent suspension is an unnecessary complication in an offroad trailer and adds things that can fail and not be easily replaceable. That said, a couple of things that might be worth considering:
When it became apparent that the little outer bearing on a standard trailer setup was inadequate, I replaced my standard trailer axle and hubs with a custom setup wherein I machined a 40x40 square axle shaft to fit inside the hollow LR stub axle spindles. The LR spindle is welded in place over the 40x40 axle and allows me to not only use the large parallel bearings but also original LR hubs and even LR disc brakes. Obviously takes LR wheels with the stock nuts too. Mine is a solid axle with toyota FJ55 leaf springs but this could easily be done with short axles- easier actually as you don't need a lathe with a huge spindle bore to take the long axle. I used bits i had lying around, but I'm sure you could pick up a couple of LR hubs and spindles cheaper than the trailer hubs with LR stud pattern.

I took my drawbar back to the side chassis rails at the front suspension hanger attachment point and welded the back end of the drawbar RHS to the front edge of the spring hangers, giving a very robust connection between the chassis, drawbar and suspension.

Just as an aside- I was taught way back that leaf springs have an inherent damping effect in the sliding friction between the leaves. I don't have any other damping on my trailer and have never felt a need for it. Also, using clamp plates and straight bolts instead of U-bolts does away with a major failure point in leaf spring arrangements.

[roverrescue]

I agree with POD that he best bearings,hubs and brakes you will find for a trailer come from a being wrecked disco! Rears are probably easier than fronts buut not much in it.

Turn up some bolt flanges to weld to your axles or swing arms and then just bolt up the stub axle, hub and wheel as per Solihull

S

[weeds]

post 9 in this thread http://www.aulro.com/afvb/projects-tutorials/125879-hcpu-tub-trailer.html for a custom axle using land rover stubs and hubs