SVA Custom Chassis
Discussion
I'm considering designing and building my own chassis, not just a locost-style setup, something more akin to the Atom. I'm trying to find info on what would be required as "proof" that the chassis has the relevant impact properties etc. Naturally I want it to be safe etc and would design it to be so, but I dont have the cash or time to invest in full crash testing lol. Could you base the design on the atom chassis design and claim it was similar to theirs assuming similar tubing dimensions etc? I have a while to plan this... 
You don't need to prove the chassis crash worthyness for an SVA. The chassis must extend a certain distance in front of the steering mechanism, provide adequate seat belt mounts etc. and be judged by the tester to be sufficently strong but there are no crash tests required.
Edited by elwe on Tuesday 11th September 18:55
Coyoteboy said:
I'm considering designing and building my own chassis, not just a locost-style setup, something more akin to the Atom. I'm trying to find info on what would be required as "proof" that the chassis has the relevant impact properties etc. Naturally I want it to be safe etc and would design it to be so, but I dont have the cash or time to invest in full crash testing lol. Could you base the design on the atom chassis design and claim it was similar to theirs assuming similar tubing dimensions etc? I have a while to plan this...
have a look at some of the locosts made AND passed an SVA and you'll quickly realise you could pretty much make the chassis out of toilet roll tubes and sticky back plastic and get it through 
Well OK, not quite, but you certainly don't have to go crash testing.
If you're worried about it give the local SVA place a ring and have a chat with them, but if you are going along the lines of the atom as you say look at their tube sizes. Or do what my Dad did and build it out of 4"x2" box section so it'll withstand a chieftain tank
(note - don't do that, unless you plan on installing an engine from said cheiftain tank)Welding, Welding, Welding. Make sure that all welds are in accordance with specs and procedures for the type of steel your'e welding. Then, crack test, X ray if poss. all welds.
I can stick most metals together with oxy / acetylene, Mig, Tig. Stick. But, on a performance car frame, no. Fine if you are happy to use the car yourself, notwithstanding the danger to others if a weld goes south on a roundabout on the A1. Also ensure that the steel is certified for the purpose.
I can stick most metals together with oxy / acetylene, Mig, Tig. Stick. But, on a performance car frame, no. Fine if you are happy to use the car yourself, notwithstanding the danger to others if a weld goes south on a roundabout on the A1. Also ensure that the steel is certified for the purpose.
OK, some good tips in there. I'm not the best welder in the world but Id certainly practice a lot before doing a project like this, and section them to ensure i was getting good penetration and not just brazing lol. I do tend to over-engineer things as a matter of course but naturally I'd be looking to save weight on this sort of project. Ive hunted round a lot for the details of whats required and as mentioned it seems to be "it looks car shaped, it seems strong enough, its got no sharp bits and the seatbelts are secure....pass". Im sure its not quite that simple but I've downloaded the pdf and will read it through. I've got a couple of books out the library on race-car chassis design too, should all help. Thanks for all your input so far!
Coyoteboy said:
OK, some good tips in there. I'm not the best welder in the world but Id certainly practice a lot before doing a project like this, and section them to ensure i was getting good penetration and not just brazing lol. I do tend to over-engineer things as a matter of course but naturally I'd be looking to save weight on this sort of project. Ive hunted round a lot for the details of whats required and as mentioned it seems to be "it looks car shaped, it seems strong enough, its got no sharp bits and the seatbelts are secure....pass". Im sure its not quite that simple but I've downloaded the pdf and will read it through. I've got a couple of books out the library on race-car chassis design too, should all help. Thanks for all your input so far!
If you aren't 100% on your welding I'd recommend more overkill on the filleting - at least with fillets you can instantly see you've got a good join, and they add booger all weight really.Good point. I was hoping to use some of the chassis members as pipework - somewhat atom-like tubing of sufficient dimensions carry the air fowards to the intercooler and back to the engine - extra use of existing pipework to save weight. Need to find out what wall thinkness they use. I think i'd leave water to normal hose
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