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260Z Track Car Build(Recreation of My Dad's GT2 Race Car)

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Its not for door to door racing.(could change) I will be doing a few time trials and some auto cross, Pittsburgh has a pretty big vintage Grand Prix they run out here. What do you see that could be a problem? 

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The fabrication work on the cage looks like it's well executed, however in addition to Jon's comment, I see some other design flaws. To the best of my knowledge the crumple zone's should not be reinforced as they are critical to dissipating energy in a collision. Even more trouble is that the bottom of the rear stays tie into the bars connecting the rear strut towers to the rear of the car. It seems to me that if the car were to be hit from the rear, rollover protection could be instantly compromised. I have seen rally cars built with some reinforcement at the front to preserve the unibody in colision and allow the car to keep competing, but that still carries the same safety issues.  Also what is the purpose of the loops of bar stock welded to the harness bar? Surely those aren't meant to be the harness mounting points...

 

Edit: Jon, just looking the NASA (rally) roll structures spec, it seems that configuration should be allowed. Unless I'm looking at the photos wrong, it looks to match configuration mrc-4 in diagram 2.1: http://www.nasarallysport.com/rules-forms/2012-NASA-Rally-Sport-GRR-Appendix-B.pdf I seem to recall FIA allowing the same layouts, haven't looked into SCCA

 

As well, by that spec the structure can extend beyond the front and rear strut towers, justified as a measure to protect a fuel cell, but I've always seen such a thing done as a standalone structure. I'd would be very hesitant to use such a structure as a foundation for the rear stays, especially where it makes a ~60 degree bend right before the footplate. 

Edited by m1ghtymaxXx

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The fabrication work on the cage looks like it's well executed, however in addition to Jon's comment, I see some other design flaws. To the best of my knowledge the crumple zone's should not be reinforced as they are critical to dissipating energy in a collision. Even more trouble is that the bottom of the rear stays tie into the bars connecting the rear strut towers to the rear of the car. It seems to me that if the car were to be hit from the rear, rollover protection could be instantly compromised. I have seen rally cars built with some reinforcement at the front to preserve the unibody in colision and allow the car to keep competing, but that still carries the same safety issues.  Also what is the purpose of the loops of bar stock welded to the harness bar? Surely those aren't meant to be the harness mounting points...

 

Edit: Jon, just looking the NASA (rally) roll structures spec, it seems that configuration should be allowed. Unless I'm looking at the photos wrong, it looks to match configuration mrc-4 in diagram 2.1: http://www.nasarallysport.com/rules-forms/2012-NASA-Rally-Sport-GRR-Appendix-B.pdf I seem to recall FIA allowing the same layouts, haven't looked into SCCA

I'm sure the loops are just to keep the belts from sliding around on the larger bar. SCCA has some weird rules, I'm sure the cage is strong enough with the diag as it is, but it is technically not correct. Door bars would need some work but you can work with what is there already, don't have to cut that stuff out to fix it.

 

I totally agree with you about the tubes that go all the way out to the ends of the car. Unnecessary and less safe, particularly in the rear as you said. I do think that a tech inspector would probably let it go though, if they let Mike Kelly's go. I believe he said an inspector signed off on his.

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Just a footnote: two additional door bars are being added as well as a jacking point.  We agree about the diagonal bar, however this design has been used on many cages that have all passed tech. The cage was actually built by a former Nissan Off-Road team fabricator.

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Need double door bars or an "X". The rear main hoop braces must end at a chassis attachment point, not on another tube. That will fail NASA, SCCA, VARA, HSR West, and NHRA tech. It's a really bad idea. A rear impact that bends the bars going to the back of the car will bend the stays and possibly move the main hoop.

 

Who is the fabricator? I know a bunch of the NPTI, T-Mag guys.

 

Remember, off-road roll cage design is based on single vehicle wrecks. Road race cage design is based on multiple vehicle wrecks.

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If it's not too late I would fix the cage to make it SCCA NASA compliant. It's much easier to do it now than later.

 

Why go to all this trouble without making it fully usable? Why hold back it's potential? It may cost more to correct but it should have been done right in the first place, at that point it wouldn't have cost any more.

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