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New OEM Hardtop Rule G 2


dans2k

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  • 2 weeks later...

Good luck getting it fixed. Try Greg at GT Motoring for lexan pre-formed. Not sure on his cost but worth a try. Other than him, see if Honda Performance Development can get the glass for cheap.

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  • 2 weeks later...
If you were to alter the OEM mounting points for an S2000 OEM top, would that be chassis stiffening +3 points?

 

do you realy want us to come and run in TTB?

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clydesdale
If you were to alter the OEM mounting points for an S2000 OEM top, would that be chassis stiffening +3 points?

 

do you realy want us to come and run in TTB?

 

 

What I'd really like is to establish whether changing the mounting of a roof/top is chassis stiffening regardless of whether or not you believe it's part of the chassis. If it applies to a convertible it should apply to a coupe. Who determines if a part is reinforcement or not? If I put a carbon fiber roof on my convertible or coupe is it chassis stiffening or not? If I rebuild the OEM roof mounts for my convertible or coupe is it chassis stiffening or not? This thread has certainly addressed the aerodynamic nature of the top, I was interested in the structural nature as well.

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I don't think its an issue maybe if you welded the thing on the car?

 

I don't think anyones going to go to the trouble of fabricating some structural stifenning hardtop mountpoints or welding it on when you can weld a cage or rollbar for free.. unless they are mad maybe

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obzezzed350

That would be laid out here...no?

 

4) Add or modify other chassis stiffening devices or fabricated parts (such as lower strut braces

or lower arm braces (with greater than two attachment points), subframe connectors,

subframe braces, subframe mounts/bushings, etc) +3

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clydesdale
I don't think its an issue maybe if you welded the thing on the car?

 

I don't think anyones going to go to the trouble of fabricating some structural stifenning hardtop mountpoints or welding it on when you can weld a cage or rollbar for free.. unless they are mad maybe

 

Not free, +2 points if the cage happens to be welded to the A,B,C pillars, roof, windshield frame, etc. We also know that just because something doesn't work effectively doesn't mean it doesn't take points if you do it. In my case I'd like to do a lightweight carbon fiber roof. Is the roof considered non-essential in which case it can be lightened with no points or does it add or modify chassis stiffness?

 

That would be laid out here...no?

 

4) Add or modify other chassis stiffening devices or fabricated parts (such as lower strut braces

or lower arm braces (with greater than two attachment points), subframe connectors,

subframe braces, subframe mounts/bushings, etc) +3

 

I would imagine so. However having been the owner of a targa top vehicle there is a distinct difference in the car with the top in and the top out. Is that a subjective chassis stiffening device? If there wasn't a noticeable difference does that make it not a chassis stiffening device? If I change it to carbon fiber is it any stiffer? If I reinforce the brackets that hold it in place is that a modification? Now for the sake of argument remove the B-pillar and make it a convertible. Using the same hypothetical questions does anything change? Now change it to a coupe and take the steel roof off and put in carbon fiber or change the brackets-- still the same?

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>> In my case I'd like to do a lightweight carbon fiber roof. Is the roof considered non-essential in which case it can be lightened with no points or does it add or modify chassis stiffness?

 

I think the rules say you can change panels as long as they are the same shape so why not?

did you ask the chief and he say no or something?

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clydesdale

I have not made any request to Greg about this. I was hoping to get a feel for whether or not the top/roof should be considered more integral to the function of the chassis. I have not attempted to replace my own roof for this very reason yet I've seen cases-- S2000 and C5Z among them-- where it is just assumed that the top has no function and is modified for no points. My opinion is that it should be either non-essential for everyone or integral for everyone. Given that I take 2 points for welding my cage to the roof line, it seems that the chassis stiffening concept of the roof is reflected in the rules. With that said, does my point have enough merit to bother Greg about it?

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I have not made any request to Greg about this. I was hoping to get a feel for whether or not the top/roof should be considered more integral to the function of the chassis. I have not attempted to replace my own roof for this very reason yet I've seen cases-- S2000 and C5Z among them-- where it is just assumed that the top has no function and is modified for no points. My opinion is that it should be either non-essential for everyone or integral for everyone. Given that I take 2 points for welding my cage to the roof line, it seems that the chassis stiffening concept of the roof is reflected in the rules. With that said, does my point have enough merit to bother Greg about it?

I can tell you as a Miata owner that the roof has zero bearing on the structural rigidity of the car. Perhaps it makes a difference in a car without a cage, but in a caged Miata it's dead weight, up high. I have my doubts that it would even make a difference in an uncaged car though - before I had a custom cage put in my car just had a rollbar, and the top had stress cracks in it... so the chassis was definitely stronger than the top. Maybe this is different for Corvettes and S2000's, but that's how it works on the Miata.

 

I can see the aero benefits of a hardtop (as argued in the previous 50 pages) but nothing in my eyes would give any structural benefit to a fiberglass top.

 

Patrick

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TurboShortBus
With that said, does my point have enough merit to bother Greg about it?

I always "bother" Greg with my pissant little ideas and points, and on occasion, some of them actually have merit and affect the rules. Go for it.

 

In the example of an SN95 Mustang convertible, I don't see how an extensively-attached OEM removable hardtop (they did exist, albeit briefly) could provide any more stiffness than a typical coupe chassis does. But, I don't have a chassis rig at the house, either.

 

Mark

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