Outer Limits 4x4 Board

I would like to pose a question for the gurus. Instead of building a bent tube hoop-type arch for the b-pillar, I was thinking about using a T joint. This would get a tighter fitment for internal cage application. If this was trussed and the welds were of good quality, how strong would it be compared to using bent tube for the b-pillar? The horizonal tube end will be capped with 3mm steel.

Hi NAM
With good welds etc it would be stronger then a bend because it is made up of straight lines.
A bend is already a weak point, ie triangle versus curve.
J Top

I cant see a problem with it so long as all joins/welds are as you say of the best qaulity and that the truss pillar or diagonal brace is positioned in such a way that it ties the horizontal and vertical pillars together...other than that it probably isnt pleasing to the eye to look at....also as you mention about internal application and the fact that this is harder to weld all the way around inside the vehicle....apart from that it looks like more work to fab and weld it that way and if it is for competiton or racing will it satisfy governing bodies like c.a.m.s or engineers and those who scrutineer the vehicle at events etc....
anyhow thats just the way I look at it
thanks Eddy

cool thanks guys. the reason why i though about doing it this way was so that i could fabricate the roof "halo" section outside of the car. i would have easy access to weld all the way around on each join. then i plan on positioning it in the car and tacking on the a-pillar verticals. then tilting the thing backwards, so that i'd have room to fully weld the a-pillar bits. then stand it up again, tack the b-pillar verticals, then fully weld. it's easier to weld the b-pillar than the a-pillar, while the thing is in position. i should have good access all the way around for the rest of the joins. that's the plan anyway. it would also fit much closer to the roof than if i was to bend up the pillar hoops.

Check your local rules as I think you may find it very hard to get it approved if you are looking at racing or registration.

Brad wrote:Check your local rules as I think you may find it very hard to get it approved if you are looking at racing or registration.

clarify why?

firstly, i'm not building it to compete so i'm not really too fussed about rules. secondly, in VIC cages don't need to be engineered and there are pretty loose guidelines on construction. i just want to survive a hard roll. the body is not a big concern.

but just for curiosity, does anyone have a link to XRCC cage specs?

I think this is current

G 3 A ROLL CAGE - 6 point Full Cage mounted to frame with diagonal brace on main hoop from drivers side down to passenger side. All tube work in drivers head area to be padded appropriately. Overhead bracing must include at least one diagonal brace from front to rear hoop and two front hoop to rear hoop straight braces. Open top vehicles to have steel (1.6mm) or alloy (3mm) roof sheeting to cover drivers area welded or bolted to cage. Seats are to be mounted to cage either directly or with brackets and at least grade 8 fasteners.) At least a 4 point approved harness is to be fitted for the driver.

5G 3B Approved Materials and fastening / fusion standards for the construction of cages and chassis:
Structural Materials

Minimum material standards for reinforcement of chassis:

300 grade, 3mm steel plate
Aluminium prohibited for chassis reinforcement.
Minimum material standards for construction of chassis:

300 grade, 3mm steel RHS and/or
300 grade DOM steel of at least nominal 3.2mm wall thickness & and 39mm nominal OD.
Aluminium is prohibited for chassis.
Minimum material standards for construction of roll cages:

300 grade DOM steel of at least nominal 3.2mm wall thickness and 39mm nominal OD.
Aluminium - T6 or other aircraft grade, 65mm nominal OD x 5mm nominal wall thickness. Additional triangulation required for aluminium roll cages - Refer XRCC Director.
All bends to be of “Mandrel” quality, no distortion in tube allowed.
Welding

Methods of welding to be: MIG or TIG
Due to the heat affected zone when applied to chassis and frames Oxygen/Diluted Acetylene welding (Oxy) is prohibited.

Fasteners
Original equipment or aftermarket fasteners of at least grade 8 for all chassis, frame, winch and recovery fixtures
Stainless Steel Fasteners – Prohibited on all frames, cages and their fixtures.
Chassis/Frame Galvanising is Prohibited

thanks pete. no stipulation on joints there.

i searched pirate for buggies with no bends. they look fine to me.