A question about the length of subframe.
Is there a legal requirement that subframe can't be made longer than the chassis?
As per regulation rear hang behind the axle (or center of rear wheel) can't be more than 60% of the wheelbase (my truck is 2780mm so it will be 1660mm). I measured my chassis extends up to 1240mm. So can I make subframe longer than chassis up to 1660mm?
Hi Brij,
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There is no legal requirement there....however any subframe must be mounted to the approval of and signed off by an engineer..... so you need to get a Qld Blue/Modplate no matter what. Subframes longer than the chassis are common. The subframe of course needs to be strong enough to support the overhanging weight.....if not then the aft section of the chassis is typically extended to help support that weight.
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If your WB is 2780 then it should be the original SWB and 1668mm sounds right for the maximum rear overhang. Brij, do not make the mistake of making the rear of the body 1660mm overhang and then adding things to the rear wall. When Transport says "Maximum Rear Overhang" that is exactly what they mean and this includes absolutely any permanent fixture on the rear of the body, eg: spare wheels, antennas, lights, racks of any description, etc. Make sure you allow plenty of length for that sort of stuff. I've seen a body knocked back on the thickness of the rear end outline marker lights!!! And another knocked back on the thickness of the hinge pins of the tailgate!!!! I hope you get the point.
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FYI, 3500mm is a common body length for a SWB FG637/649 and should allow enough for a rear bumper with a spare wheel(s) mounted up on it.
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Regards John
