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I have loved ERA's cars for a very long time. I remember seeing a very early two-digit car at a local car club's "Car-B-Que"/get-together. The ERA looked immaculate in almost every respect. The only problem that I could see after a couple of decades of use was that the clear coat on the wheels was cracking.
"Who makes the best replica?" is a question that cannot be answered empirically. However, the thread starter cannot go wrong with an ERA. It's gets my endorsement, but then, that's worth absolutely nothing here on Earth. |
Rectangular frames versus round frames...
Round frames are by their nature, stronger. Any corners, are inherently weaker than their surrounding material. Bob |
It is highly probable that JBL makes the strongest standard frame in the Cobra replica business, and they have even tested it. "....very stiff (minimum 24 HZ frequency) chassis with torsional numbers above 4500 lbs per degree". If anyone wants to bet differently and get theirs tested, put me down for 100 bucks on the JBL side.
Oh yeah, and this even goes for the other suspension parts like control arms, mounting points etc. |
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Round stronger than square? NO WAY!
...my moneys on the JBL, by the way, and will someone get Jamo a screen cleaner. :D |
Pound for pound, round tubing is stronger than square tubing. Of course, there are different ways to measure strength.
If you bend a square tube across the corners instead of across the flats, see what happens. Failure starts at the corners because the stress gets high there without supplying a lot of moment to take the load, because there isn't much material out there in the corner. So, if you know the orientation of the load, square is probably better. If not, or if there are many possible loads, then round is better. Important thing to remember is that strength goes down rapidly with an increase in length ; by the square of the length in fact. No desire to argue, suspect it comes down to a discussion of strength versus weight. |
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Many race cars in the fifties and sixties used round tubing in their construction including Ferrari, Maserati, AC (Shelby), Kurtis and Watson Indy cars and dozens of others. In the seventies, racers started using rectangular tubing because a crash usually limited the damage to a localized area (impact area). A round tube race car was usually trashed after a hard crash, whereas a car made from rectangular tubing had only to replace a front or rear clip, as is done even now with Nascar Cup and Modifieds. I think rectangular tubing was pioneered by Detriot auto makers for passenger cars in the twenties and thirties, and they were tanks.
Back to Kirkham, in my opinion they use 4 inch round tubing because it is as the originals were made by AC/Shelby, and thus are the more accurate replica. I'm not beating up on ANY Cobra here (no pun intended), as they all have their highlights. |
Square tubing is indeed much stronger supporting vertical loads than round tubing where the round tubing is of equal diameter to the height of the square tubing. For loads that are changing across the diagonal of the tubing, in other words coming from multiple directions, the round tubing is marginally stronger than the rectangular tubing.
Most frames, whether round or square, have a lot of horizontal cross bracing running parallel with the main chassis rails which help support non-vertical loads. So I think because of this the square frame, pound for pound, should be stronger. BUT I agree the round style is more "Correct", and either tubing can be built plenty strong for these cars. FFRs round tube design looks very well engineered to me, and is their best feature IMHO. |
Hi guys,
I know we are from Canada but we do make nice car. We have the most leg room for 90'' car. Just my 2 cent Don, |
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The "I" value for a 3.00 diameter, .125 wall round tube is 1.17 inches to the fourth. The "I" value for a 3.00 x 3.00, .125 thick wall square tube is 1.98 inches to the fourth. Sorry for the same size a square tube is stronger. |
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Indeed the recent changes for the NEW ERA's is pretty impressive. After all, what do you to make a car all ready 'perfect' even better? :LOL:
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As far as I know, there's no dispute in/on Club Cobra that ERA is an awesome product, but to state that it's the most modern and best engineered Cobra on the market is arguable and you do say that it's your opinion. I know that many of the Cobra companies such as SPF, FFR and Kirkham have changed their product over time to make their cars better. I know the Kirkham better than the others, since I own one, and I know the Kirkhams have continually made improvements to their car including making it the lightest on the market. I think, but I'm not 100% sure. Based on a thread by Joe at Kirkham, the latest Kirkham's with an aluminum FE are about 2,150 lbs. I have no idea what a ERA weighs, but I'm guessing that it's about 300-500 lbs heavier. That extra weight may buy you higher frame rigidity, but at the expense of a heavier car.
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Does 'lighter' make it 'better'? Unless it's a race car, I think not.
"The beat goes on" |
I said the "I know the Kirkham better" and I said I think the Kirkham is lighter, but I did NOT say that lighter makes it better. It may be better it may not be better, but extra weight doesn't guarantee better either.
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They're really not the same size. A square tube is also about 27% heavier. Even though a round intake port is the most efficient, your analogy is like saying a square 3" intake port will flow more than a 3" round port, which it will. |
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