Aluminium Trailer & Axle spec - Advice/Suggestions Please

[Gascamp]

Hi All

Great forum for reference & Ideas here thx.

I am very close to having a Custom trailer in Aluminum fabricated locally (Sunshine Coast, Qld) .... I'm aware of the fact
the Aluminum not having the structural strength of steel but I am after a "lightweight" tow in comparison & mainly for beach (ha but not only !!) trips & carrying SUP's & kayaks.
I've had a "warning" from a steel fabricator of the Aluminum cracking after time around the drawbar/chassis area - so interested to hear if any other forum members have had experiences (good or bad) with the Aluminum.
Specs:
7 x 4 Box trailer 500 sides
(multi-use for general trailer & racks for sup/kayaks, tonnue cover & awning, storage box & 12 volt wiring
- Drifter DOT style concept !!)
Track width as per tow car, Off road coupling etc etc
drawbar / chassis 100x50x6mm structural box and 100x50x7.9mm structural channel
sides, guards , sides, etc 3mm marine grade treadplate , floor 3mm flatsheet

AXLE ISSUE -
Axle size 50mm square nominated is SHS (hollow) ??
Most I see out there are 45mm solid but guy I'm using swears by using the 50mm hollow saying it is stronger than the 45mm solid or even 50mm solid.
Maybe "technically" stronger - but forum users experience with caravaning & Off Road campertrailers.... any known issues with rough tracks, corrugations how a hollow axle performs ??


Thanks for any advice in advance
Grant

[robcaz]

Hi Grant,

What is your estimated GTM or Gross Trailer Mass??? Adding a water tank, a couple of jerrys, firewood, as well as your food etc for remote camping will quickly put the GTM over 750kg where you are required to add brakes to the trailer. A fully loaded off road camper trailer can easily weigh between 1300kg to 1500kg.

I assume you are talking about beam axles??? For off road use on corrugated roads & rough off road trails I would be sticking with a tried & tested 45mm square solid beam axle over an axle made from RHS which would be more suited to a trailer designed to carry much lighter loads over well formed roads.

You will find recommended axle & bearing sizes listed on the tech tips page with charts reproduced with permission from Vehicle Components http://www.campertrailers.org/axles_bearings.htm You will note that the Vehicle Components SLM bearing series is rated at two tonne as they use a combination of a Ford inner bearing used as the inner & a Holden inner bearing used as the outer.

If you were looking at a heavier GTM over 750kg I would also be using larger RHS in the fabrication of the drawbar such as 75 x 50mm. Too often the Aframe is also used to carry gear in a storage box adding more weight to that area. My thoughts on what makes a good off road trailer http://www.campertrailers.org/off_road_trailer.htm

Hope his helps.

[Gascamp]

Hi Rob & Carol.... thx for the reply on this.

Yeh I did check your axle/bearings page without mention of SHS (hollow) so I'm asking around.

It was also the obvious of Aluminum not equal in strength as Steel although with two fabricators on Sunshine Coast I have looked at & both doing offroad it is an option I'm interested in - just looking at carefully.
Just hearing from the steel fabricator where I also got a quote from re: the "cracking" I'm after a few pros/cons on the Aluminum but with not so many people around having gone with Al. - so few & far between !!

Going with heavy duty eye to eye leafs (with shocks an option tbc) & yes electric braked & have a GVM of 1600kg.... (320 Tare)
... This with the drawbar / chassis 100x50x6mm structural box and 100x50x7.9mm structural channel

Other specs - removable Kayak racks with brackets/extensions to enable awning or tarp right over for Blackwolf tent under, tonneau cover over with lockable storage under, 12v setup, Drifter style kitchen built etc

I have a lot of bookmarks going !! Yep Gone over the "what makes a good offroad" very impressed with all the info gathered off the website... lot of reading todo

The Axle -
I will likely go with the 45mm solid as you suggested - to date i can't see any technical reason to use SHS even being the greater 50mm as per the fabricators std.

I'll keep you all posted with how the final spec ends up & how the build goes.

Thanks for your input - will always be greatly appreciated.

Thx Grant

[robcaz]

Hi Grant,

Also worth having a chat with Rob Moore at Jimboomba Campers in Beaudesert http://www.jimboombacampertrailers.com.au/ Rob & his two boys fabricate aluminium trailers & have some great ideas that would no doubt be very helpful in sorting out a design for you. We dropped in at the workshop recently & were very impressed with the quality of the work.

[Gascamp]

Thx for that

... Interesting that Jimboomba Campers use a "Galvanised Steel Chassis" with a bonding agent & tensile bolts for fixing to the Al. Body.

The fabricators I'm looking at are using Structural RHS & Channel Aluminum.

http://www.aluminiumtrailers.com.au/

http://lifetimetrailers.com.au/

Research still being done
& I'll give Jimboomba a ring.


Cheers

Grant