Steel, al­loy or plas­tic? Full hoops or none? Ev­ery­thing you’ve ever wanted to know about arm­ing your 4x4 with the right bull­bar.

4 x 4 Australia - - Contents - WORDS DANIEL EVERETT

ABULLBAR is the cor­ner­stone of all four-wheel drive builds. It’s the build­ing block that will de­fine your 4x4 more than any other ac­ces­sory. Con­sider this: There are two iden­ti­cal 4x4s sit­ting in the work­shop about to be trans­formed into off-road rigs. One is go­ing to be fit­ted with a sleek, colour-coded steel bumper with a hid­den winch mount; the other is des­tined for a no-non­sense five-poster. It’s ob­vi­ous the di­rec­tion both of th­ese builds will be tak­ing, and what each ve­hi­cle will be used for.

How­ever, with so many op­tions on the mar­ket, it can be dif­fi­cult to nar­row down what will work on your 4x4.

In years gone by it was a whole lot eas­ier: look at the three or four bull­bars that would fit your 4x4, buy the one you liked the look of and fit it. Th­ese days we’re spoilt for choice, with op­tions rang­ing from hid­den winch mounts in­side the fac­tory bumper right through to steel bull­bars that’d mow down a full-grown cow with­out flinch­ing.

So we’ve de­cided to cut through the mar­ket­ing jar­gon and bring you the ‘no BS’ guide to buy­ing the right bull­bar for your 4x4.

We have en­listed the help of some of the largest bull­bar man­u­fac­tur­ers in the world, in or­der to es­tab­lish what the real dif­fer­ences are be­tween steel, al­loy, and plas­tic, and we’ll out­line the pros and cons of ev­ery bull­bar de­sign you can imag­ine. Most im­por­tantly, we’ll tell you what is le­gal to fit to your 4x4.


BE­FORE you worry about pol­ished fair­leads and built-in bot­tle open­ers, the first ma­jor de­ci­sion is the ac­tual ma­te­rial your new bull­bar will be con­structed from. In days of old you chose steel if you wanted some­thing heavy-duty, or al­loy if you liked your ad­ven­tures on the fancy side. With the in­tro­duc­tion of plas­tic and high-strength al­loy bull­bars, things aren’t so sim­ple any­more.

The main fac­tors to con­sider are den­sity and ten­sile strength. Put sim­ply, den­sity is the heav­i­ness of a ma­te­rial at a set vol­ume, so in this case 1cm3 of steel, al­loy or plas­tic. Ten­sile strength is the max­i­mum force a given ma­te­rial can han­dle be­fore fail­ing.

At first glance steel is the clear win­ner in the ten­sile strength game, with a rat­ing of roughly 2750kg/cm2, com­pared to alu­minium with 2300kg/ cm2 and LLDPE (lin­ear low-den­sity poly­eth­yl­ene) with 305kg/cm2. Of course, all of this is de­pen­dent on the qual­ity of ma­te­ri­als used, but it still doesn’t take into ac­count a lot of very im­por­tant fac­tors.

The first is den­sity. A 1cm3 chunk of steel will weigh three times as much as a same-sized cube of alu­minium, and al­most 10 times as much as LLDPE in the same size, mean­ing you could have a 10cm thick slab of LLDPE for the same weight as 1cm of steel. This is some­thing en­gi­neers take into con­sid­er­a­tion and use to their ad­van­tage.

Adam Craze from Iron­man 4x4 said: “With bet­ter grades of alu­minium, we can de­sign

an al­loy bar with the strength prop­er­ties close to that of a steel but with a weight sav­ing of around 30 per cent.”

By us­ing alu­minium or LLDPE, com­pa­nies are able to of­fer close to the same pro­tec­tion lev­els but with a dras­ti­cally re­duced weight over the front sus­pen­sion, eat­ing into the GVM con­sid­er­ably less in the process. Adam Hixon from Smart­bar claims this de­crease in weight sees their bars re­duc­ing fuel con­sump­tion by as much as seven per cent.

The next ma­jor fac­tor to con­sider is how they hold up over time. Tra­di­tion­ally this has been one of the big­gest draw­cards of steel. It has a higher en­durance limit than alu­minium, which means small forces ap­plied to alu­minium, like re­peated knocks and harsh cor­ru­ga­tions, will even­tu­ally take their toll, whereas steel will ei­ther fare bet­ter or not be af­fected at all.

So what does this mean for the buyer? Es­sen­tially noth­ing. In terms of im­por­tance, the ma­te­ri­als used run a very dis­tant sec­ond place to de­sign. They’re es­sen­tially tools for the en­gi­neers to work with to meet a de­sired out­come. Ma­te­rial thick­ness, qual­ity and in­ter­nal brac­ing can mit­i­gate any po­ten­tial ad­van­tages of one ma­te­rial over the other. Alu­minium can be run at a thicker gauge and can have ad­di­tional brac­ing or dif­fer­ent ma­te­rial com­po­si­tions to bring it up to com­par­a­tive strength lev­els with steel. Like­wise, LLDPE can be Uv-sta­bilised for longevity and have ad­di­tives mixed in to up its ten­sile strength while still be­ing eas­ily re­pairable and po­ten­tially safer for pedes­tri­ans.

Ul­ti­mately the real dif­fer­ence for con­sumers is es­sen­tially what you can see. Steel re­quires far less work and is cheaper to pur­chase, mak­ing the off-theshelf price cheaper. Alu­minium will gen­er­ally weigh less, giv­ing you an in­crease in fuel econ­omy. Plas­tic can be lighter again, im­prov­ing fuel econ­omy and safety lev­els. While steel may tra­di­tion­ally be used for strength (and al­loy for show) it all comes down to build qual­ity in the end. Stronger ma­te­ri­als won’t make up for bad de­sign and shoddy qual­ity.


WHILE the griz­zled old man

Laser-cut­ting bull­bars at ARB.

Alu­minum Iron­man 4x4 bars are al­most as strong as steel, but weigh up to 30 per cent less.

Bull­bar engi­neer­ing and man­u­fac­tur­ing at the ARB fac­tory. The Smart­bar is made from LLDPE, so it weighs much less than a steel bull­bar.

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