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Ok I am building a Cabrio which I know is different but are there any Sportster builders out there who will have to put their car through IVA.
If so what is the view on the fuel tank requirement regards rear collision impact.
The IVA manual states the tank must not be positioned so as to be at risk of puncture from sharp edges or objects in the event of a rear end impact.
My view is that although the tank on the Cabrio and Sportster is sat in a chassis frame it has a lot of tank exposed below the chassis line which is at risk from rear end impact. On my Cabrio I have about 2cm clearance between the front face of the tank and the diff mounting bracket which means if the chassis collapses at all under impact the tank hits the diff mount.
I can't see my Cabrio tank position passing IVA based on my interpretation of the IVA requirement and I don't think the Sportster would either.
Should I be concerned?, more to the point should you Sportster builders be concerned. Adding tether straps to fuel caps and such no brainer issues like that are not a concern. Moving the tank location however in a car with the limitations of a Cabrio or Sportster is.
Thoughts and opinions please or should I just order a skip now for my labour of love!!
I think it is going to be a bit of trial and error or 'suck it and see'.
If you can raise the fuel tank within the boot as high as possible, that might help.
Otherwise I would submit it for a test and see what they say. If they do have a problem you can discuss with them possible solutions and what they would be prepared to pass. Maybe some protection plates welded to the chassis would be enough.
The other idea is I think the Cabrio has quite a lot of space behind the seats? Maybe you could have a custom tank made to fit there and then box it in with something suitable and covered with vinyl trim like Simon's car.
Personally, i'd put it in for a test and then modify what is necessary rather than go to a lot of expense making custom parts,, . It might be cheaper in the long run.
I'm sure you shouldn't skip it! With the closure of Javelin, there will never be any more new Cabrios made so its got to be worth having a go.........
Here's the location of the tank on my Sportster - The same place as everyone else's, give or take a couple of mm in each direction.
These spacers move the tank back enough to clear the diff hanger.
I'd have a chat with Marlin - they'll be in the same position when it comes to putting turnkey Sportsters through IVA, so I assume they'll have a view on it.
I'd be surprised if this was an issue given that the Cabrio & Sportster tanks sit within quite a substantial chassis frame (which itself has no sharp edges) and the bumpers are mounted on collapsible struts.
The only potential issue could be contact with the diff in which case I wonder whether a simple curved shield mounted on the back of the diff might suffice (ie to protect the tank against the 'sharp' edges). If that isn't sufficient then surely alot of current production cars wouldn't pass either?!
Hopefully the IVA testers will continue to use a sensible approach when interpreting the IVA rules (which was my experience with the SVA test).
I wonder if you could get some advice from your local SVA station on whether it's likely to be an issue or not and, if so, what they would recommend doing (my SVA tester was very forth coming with easy to implement suggestions).
It would be a shame to not get your car on the road given what a good job you've done & all the hard work you've put in !
Sounds like I am not on my own here and others have come to similar conclusions. Simon I think your right the best way may be to build some shielding around the diff mount. I also think I will try to build something to shield the tank from the rear.
Robin I share your views on the tank position but mine is already built in the Marlin designed position so I will try to shield it rather than move it. I remain unconvinced they will continue to allow the exhaust to run near or under the tank even if it is heat shielded. I plan on modifying my exhaust to side exit in front of the NS rear wheel under the runner board if I can't definiteley clear the tank with a rear exit system. Currently the tailpipe does go under the NS corner of the tank. I have made provision for a heat shield between the exhuast and the tank but the IVA notes talk about in the event of the tank leaking it should not be possible for fuel to hit the exhaust and even with a heat shield in place on my current setup it would probably allow this.
I will try to take some pictures of the IVA mods I make as I go.
Looking at the picture provided of the Sportster tank it may not be as bad as the Cabrio. Mine has the Marlin supplied 12 gallon tank which has a cut out in it to allow it to wrap around the diff, the Sportster one in the picture looks to be a smaller tank (perfect rectangle) so it may have more clearance.
The Sportster tank is 8 gallon IIRC, and has the long lower edge nearest the diff truncated at a 45 degree angle - you can just about see that in this pic, and the hanging straps are shaped to accommodate this.
