[Lex]

People often ask, Why should I buy a Factory Five Racing Cobra or Other Factory Five Kit car over some other brand??

There are probably many answers that one could give including value for money, modern design and manufacturing materials and methods, not to mention their overall success.
But for me what REALLY sums it all up is when I look at the Factory Five Frame compared to the other guys frames. Check out the following photos to see what I mean.​

This Photo shows the FFR Mk III Bare Frame done up in a black powder coat. Notice the extensive superstructure above the main 4 inch thick wall round tube frame. Of particular interest is the extensive use of triangulated steel which provides incredible strength and rigidity to the FFR Frame. Note also the strong round tube steel foot well protection as well as the extensive steel cage surrounding the passenger compartment​

Starting with the bare frame one of the first steps is to glue and rivit the first of more than 40 Panels onto the frame. Every panel that gets added increases the already rigid frames rigidity. This construction method has beem employed by the aircraft industry since its inception and is employed on the Space Shuttle today. Compare this frame and construction method to the other cobra frames pictured below​

This is a what we refer to as the "Bed Frame Construction style". Notice on this frame that other then the uprights for the front suspension the frame is devoid of any supporting structure that will provide the torsional rigidity required to keep the wheels on the road and provide a solid handling car.With this method of construction the fiberglass body will weigh upwards of 700 Lbs and is bolted onto the frame in the hope that the fiberglass itself will provide the torsional rigidity that the frame is incapable of. Problem is, fiberglass does not take well to flexing and is a poor material for this purpose. End result is a car handles poorly, Weighs a ton, and provides little or no occupant protection in the event of an accident since fiberglass shatters when hit rather than deforming and absorbing the impact like a steel chassis would do. Over time this Car will develop stress cracks that not only look bad but if left too long can comprimise the cars ability to work properly. Overall this style of build is not a good investment and is definitly not a safe car in the event of an accident.​

This is a variation on the Bed frame construction style. Note that this is an improvement over the frame shown above in that this frame at least has a small amount of superstructure above the main frame rails both in front of and behind the passenger compartment.​

Still in the event of a side hit this frame is going to crush almost into the center of the car since like Example B below there is nothing but the Fiberglass body to absorb the force of the impact in the passenger seating area, and with no triangulated steel crush zones built into the frame a front or rear end collision will not fare much better.​

As for handling due to the built in flex that this style of frame has neither of these cars will handle very well when compared to the Factory Five Chassis.​

 

[PSB]

Here we go again...hasn't this subject been beat to death, then beat some, on and on...

 

[mrmustang]

Lex,

Bed frames such as your center suggestion are a rarity these days, not sure who's kit that is. However, if your strip away the "non structural" 3/4" square tubing from the FFR frame you'll be real close to the SPF frame. Do not allow yourself to be fooled by the 3/4" tubing "birdframe". We won't even get in to the round vs square tube argument as that one has been beat to death and found to be inconsequential when comparing apples to apples crashes of one quality kit vs another.

Also, keep in mind that some manufacturers reinforce their body "tubs" (for lack of a better word at the moment), which are then bolted down to their framing system, where the FFR body is just a shell with no supports bonded in at all.

Edit: the following two links are not meant to start another US vs THEM fight, just offers another view on this subject.

CHASSIS DESIGN LOGIC

and

FFR vs another

There, I've said my piece, here is wishing you and yours a very happy holiday season and a prosperous new year.


Sincerely,

Bill S.

 

[Greg_M]

Hey Lex,

Where did you find those photos?


http://www.worldisround.com/articles/123897/photo100.html
http://www.worldisround.com/articles/123897/photo30.html
http://www.worldisround.com/articles/123897/photo31.html
http://www.worldisround.com/articles/123897/photo412.html
http://www.worldisround.com/articles/123897/photo101.html
http://www.worldisround.com/articles/123897/photo104.html
http://www.worldisround.com/articles/123897/photo102.html

Greg

 

[Magnus]

Here we go again...hasn't this subject been beat to death, then beat some, on and on...

Even if the subject has been beaten to death, there might be information that is useful for newbies or for people who are too stupid to use the "search" function, such as me.

I have read several of these threads and there seems to be some new information in each thread.

Hell, this entire forum is a whole dead-horse bash-fest for the over-done subject of building FFRs.

 

[PSB]

Even if the subject has been beaten to death, there might be information that is useful for newbies or for people who are too stupid to use the "search" function, such as me.

Well, as Bill pointed out, much of the previous discussion has been misleading and incorrect FFR Koolaid. If that's what you're after, have at it...

 

[Magnus]

Well, as Bill pointed out, much of the previous discussion has been misleading and incorrect FFR Koolaid. If that's what you're after, have at it...

The part that the frames are essentially similar if you strip away the non-structural was news to me. That is not FFR kool-aid and it is useful if you are trying to make a decision based on frame-construction.

One of these days I hope someone has enough money to spec two different brands the exact same way and put them head to head so we can see if there really is any difference. Engine, tires, gearing...everything, so we can put some of this to rest.

To add to the confusion, it has been argued that a flexing frame actually enhanced the driving characteristics of the design. Who knows?

 

[Don Payne]

Why argue, neither one is a Kirkham!

 

[mrmustang]

Why argue, neither one is a Kirkham!

Ah yes, my ultimate kit cobra goal :yes:

I've been trying to talk David Kirkham into offering me a "Kirkham in a box" like he did for a very short time several years ago.


Bill S.

 

[hoofa]

I did some Ghetto testing of my chassis:

I wasn't impressed.

 

[CobraDVM]

I'm no structural engineer, but it appears that many FFRs that get in accidents have their front and rear superstructures rebuilt and end up back on the road. There was that recent thread with a Superformance that wrecked, and the frame bent like a pretzel. The driver claimed he was doing 30 mph, but others feel he must have been going faster. I don't know what speed he was doing, but I do get the impression that FFRs fare very well in accidents compared to other makes. But this is only anecdotal so take it for what it's worth.

 

[Cardiac]

I'm no structural engineer, but it appears that many FFRs that get in accidents have their front and rear superstructures rebuilt and end up back on the road. There was that recent thread with a Superformance that wrecked, and the frame bent like a pretzel. The driver claimed he was doing 30 mph, but others feel he must have been going faster. I don't know what speed he was doing, but I do get the impression that FFRs fare very well in accidents compared to other makes. But this is only anecdotal so take it for what it's worth.

My Dad's was hit head on in an intersection at about 45-50mph. It's back on the road now after the upper structure of the frame was replaced ahead of the firewall, new lower control arms, a new front half of the body, and a few other things. Most of the car survived just fine and is still in use today.

 

[trevor]

I agree the stock FFR frame is pretty good. Large round tubes definately do a great job in torsion. I read the ERA link and all the stuff he says is true. So, it seems that ERA and FFR have a decent frame design. The Challenge frame is significantly better in torsional stiffness and bending strength - but doesnt look as nice and not ergonomic as the roadster.

The first compasrison photo is junk! That is definatley true.

I have added and will add more tubes to stiffen up my frame. We will soon see if it makes a faster race car or not

Now this is a great cobra frame. http://www.jblmotor.com/JBLchassis.html

Structural/Mechanical Engineer Trevor

 

[saki302]

All I know is most of our members seem to survive crashes with mild to no injuries with their FFRs. Good enough for me

I was a little nervous about safety, but not so much now after doing the research.

-Dave

 

[DaveT]

Frame 'B' pic date Fed 2004 appears to be a Lonestar. I'm no engineer but that's not sheet metal between the frame rails in those drop pans it's 3/16" steel plate welded in place, seams like in the event of crash that would be fairly rigid.

Dave

 

[Cone Basher]

I looked at all the kits before I bought my Coupe back in 03 and it all came down to the frame. Notice the 4 in tubes that connect the left and right side of the frame together. If you want to build a car that handles start with a rigid frame. If you don't believe me set blocks under the frame at the center line of all four tires that are the same height. Now go set a floor jack under a front A arm and lift that side as you watch. It's not "scientific" but mine flexes very little before the opposite front and rear blocks on the same side as the jack are loose.
CB

 

[tjmotter]

Why?

I did some Ghetto testing of my chassis:

 

[Don Payne]

Dude, it's Hoofa, need we say more...

 

[boeing737driver]

I've lusted after a Superformance ever since I realized how authentic looking their bodies are. And the quality of panel fit and paint are very high. Then I had the opportunity to test drive one and found the bump steer and cowl shake were not to my liking. My FFR is much tighter and more refined feeling. So, now I need to redo my body! This really is a disease isn't it? LOL

Bruce

 

[BOB SCHAEFER]

So while we're on this subject, those a Kirkham use a round tube design or are they more like Superformance? If they use the round tube design I would wonder why Superformance doesn't as it would seem the preferred design. What's the reason Superformance doesn't if it's inferior? I mean, those are the ones endorsed by CS. They are either equal or better, or is it they're cheaper to produce? I wouldn't think they're cheaper? Anybody?

Bob