Which Company makes "best" replica?

[patrickt]

Originally Posted by bret a ewing

Contemporary did the same thing with their S/C model. Virtually identical from the outside, much different on the inside.
Speaking of structural strength, any of you guys with jack pads ever actually use them or are they just cosmetic?

As I recall, even originals tended to dimple when jacked that way. But the answer is "No." Another benefit of the rectangular frame is that jacks tend to slip off them less frequently.

[RodKnock]

In my opinion, unless some independent firm performs some type of physcial testing of all the frames from the various manufacturers, calling the ERA the best of anything (engineered, original, etc.) is just hyperbole. Nonetheless, it's one of the best.

[JWilly]

Whatever your feelings are I don't think I would use the ERA site that compares the ERA to a SPF as an unbiased presentation. For example the site states: "The Superformance chassis uses 100mm x 50mm x 4mm wall (Approximately 4" x 2" x 0.160") tubing for their main rails." Then desribing the ERA it states: "The E.R.A. chassis uses 4" x 3" x .125" wall tubing for its main rails." Note, for wall thickness of the ERA rail it states .125" rather than the more acceptably used presentation of 0.125" (the way they did do it with the SPF). The way the ERA sites states it one might mistakenly think the ERA has a thicker rail wall than the SPF.

[ZOERA-SC7XX]

Originally Posted by JWilly

Whatever your feelings are I don't think I would use the ERA site that compares the ERA to a SPF as an unbiased presentation. For example the site states: "The Superformance chassis uses 100mm x 50mm x 4mm wall (Approximately 4" x 2" x 0.160") tubing for their main rails." Then desribing the ERA it states: "The E.R.A. chassis uses 4" x 3" x .125" wall tubing for its main rails." Note, for wall thickness of the ERA rail it states .125" rather than the more acceptably used presentation of 0.125" (the way they did do it with the SPF). The way the ERA sites states it one might mistakenly think the ERA has a thicker rail wall than the SPF.

1/8 inch is 1/8 inch no matter how you write it.

[jdean]

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.

[ddcobra]

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,

[Excaliber]

My Excalibur would twist like a pretzel if you picked up one corner, for a frame chasis stiffness test, thats good enough for me.

My ERA is incredibly stiff, pick up one corner and the whole car moves with it. Never had the chance to jack up an SPF.

Point is: The strength comes from how it is built more than the material thats being used. A square frame or a round can easily twist if it isn't designed properly. Seems pretty clear though that sqaure is stronger than round over all.

[RodKnock]

It's not clear to me that square is better than round, but I'm not an engineer. Unless a firm like Failure Analysis is involved, where they perform destructive testing on each and every frame/chassis, again, it's all conjecture. Also, engineering doesn't just stop at the frame. What about the rest of the car?

Also, someone earlier in this thread said that ERA has made more improvements to their car in the past year than most manufacturers make ever, but none of them are specified. Are the list of these accomplishments noted on the ERA website. Again, the ERA is a fantastic car, but so are many of the others.

[patrickt]

Originally Posted by RodKnock

Also, someone earlier in this thread said that ERA has made more improvements to their car in the past year than most manufacturers make ever, but none of them are specified. Are the list of these accomplishments noted on the ERA website. Again, the ERA is a fantastic car, but so are many of the others.

When ZOERA-SC7XX wrote that statement I believe he was referring to the massive changes that took place beginning with car #731 (2006). The statement was a bit "over-zealous."

[jmarsey]

The question: "Which Company makes "best" replica?"

My 2.5 cent answer: Kirkham (hands down)

Good luck, John

[ZOERA-SC7XX]

Originally Posted by patrickt

When ZOERA-SC7XX wrote that statement I believe he was referring to the massive changes that took place beginning with car #731 (2006). The statement was a bit "over-zealous."

If you go down to ERA in New Britain and look at a new (post #730) Cobra, you'll see that it is NOTHING like their previous cars, including mine, which is #718. Everything is new and improved, including the body, frame snout, inner fender wells (alum), trunk floor (alum), Floor, trans tunnel (alum), side body mounting, clutch master, seat frames, and probably a few more that I never noticed. And I don't mention the two year old rear end assy with outboard brakes with the Jag Salisbury posi center section. Just call and ask for Bob, who regularly posts here. The new car is awesome.

[jagxjr5012]

My 2.5 cents answer : ERA hands down !! ( then again I am bias)
I am on my second ERA and this car is now 21 years old....looks brand new....19000 miles, original paint and not a sress crack anywhere, runs awesome !!!

[ENTDOC]

never seen a stress crack on any Kirkham either, must be the extra strong frame

[Jamo]

Originally Posted by ENTDOC

never seen a stress crack on any Kirkham either, must be the extra strong frame

Spewed coffee on the screen with that one.

[RodKnock]

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.

[bdeutsch]

Rectangular frames versus round frames...

Round frames are by their nature, stronger. Any corners, are inherently weaker than their surrounding material.

Bob

[Silverback51]

Originally Posted by bdeutsch

Rectangular frames versus round frames...

Round frames are by their nature, stronger. Any corners, are inherently weaker than their surrounding material.

Bob

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.

[Anthony]

Originally Posted by Silverback51

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.

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.

[Silverback51]

Originally Posted by Anthony

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.

Okay, I was lazy.

Let go with some real frame component sizes and see what we get.

Superformance.
2 X 4 X .160 wall rectangular tubing. The "I" value of this is 3.69 Inches to the fourth.

ERA.

3 X 4 X .125 wall rectangular tubing. The "I" value of this is 3.92 Inches to the fourth.

Kirkham.

4.0 diameter X .120 wall round tubing. The "I" value of this is 2.76 Inches to the fourth.


Now this is just basic strength of materials for structural shapes and does not take into account the other structural bracing and such that makes up the frames. The only way to really compare any of these frames to determine which is the strongest would be to build a FEM model and run it through a stress program to determine what is happening when like loads are applied.

Unless one of the above manufactures has actually done this for all three frames, they cannot make any claims that theirs is the strongest.

Yes, the ERA 3 X 4 X .125 tube is the strongest, but that single component does not make it the strongest frame. All it would take would be one series of truss members to make the Kirkham tube assembly 10 times stronger.

Besides, don't beleive everything you read from manufactures (or politicians) as they are all trying to sell you something.

Is that better?

And thank you for challenging my response. I don't get to play with numbers much at work anylonger. Even this simple stuff was kind of fun.

[RodKnock]

Originally Posted by Silverback51

Kirkham.

3.0 diameter X .120 wall round tubing. The "I" value of this is 2.76 Inches to the fourth.

Per the Kirkham website, 4" round, not 3".

http://www.kirkhammotorsports.com/mfg/frame_index.html