Newbie to this forum; Best & strongest Cobra frame?

TheSaint71 · #1 (**permalink**) 02-17-2003, 04:59 PM

Hello everyone! Im new to the forum, have been watching you guys for months and finally became a member!

Anyway I am saving up for a cobra replica and will get one soon, and I need to ask you experts Cobra owners, who has the best and strongest frame? One thats also not exactly the heaviest? Im looking at kits from Unique and Factor Five, as well as some others..

ALso with to ask, aren't tube frames the strongest? As far as my research goes, this has been know since Medieval times when that stoped making their turrets and towers on their castles from square to circular...

Im excited about hearing from you guys, greatly appreciate your time

Very Truly Yours,
Jamin

soon to be Cobra owner

Carroll DeWeese · #2 (**permalink**) 02-17-2003, 05:34 PM

What do you want the car to do? The key is not the strongest frame but a frame that can handle the loads placed upon it. You need a frame that is strong enough and that is in balance with the rest of the car. If you wnat original, it will not be as strong as some of the replica frames. Some replica frames look stronger but allow more twisting than others. Determine you budget. Find the replica that fits your budget and best meets your needs. Then make sure that the frame and other parts are adequate for you purposes. If the frame and other parts are inadequate, eliminate it from consideration. Do not pick a car for its frame and sacrifice other features.

Excaliber · #3 (**permalink**) 02-17-2003, 05:53 PM

Frame would be of minimum concern to me. There all "good" with some being superior to that (JBL comes to mind). Round vs square? Not that easy, there are other considerations that come into play. Myself I prefer a square frame, easier to measure and work with.

Ernie

TheSaint71 · #4 (**permalink**) 02-17-2003, 06:15 PM

I see, as far as a budget goes, there really isnt, one... I'll have plenty of mulah to go all out

For the majority, the car will be for racing, and street driving...

Ive been trying to figure out what frame would have less 'twisting' as you said.. I totally agree, Im not picking the car for its frame, but its important still. Are there any particular kits, that make cars better for racing (my main requirement) that are good on anti-twisting? greatly appreciate your thoughts...

Jamin

thanks again Carroll and Ernie

tommachine73 · #5 (**permalink**) 02-17-2003, 07:11 PM

Saint I noticed that you are from the northwest.I got my cobra from antique & collectibles in Buffalo N.Y There frame is probably one of the best in the business.The frame is a 2x4 .wall thickness is at least 3/16 or better. There body is also one of the best I have ever seen. Joe Twombly is pretty decent and reputable,that goes a long way in this business .AIso I race my cobra and have found it very track worthy. Tom

TheSaint71 · #6 (**permalink**) 02-17-2003, 07:32 PM

Hey Tom, I just sent you a e-mail, thanks for your post, greatly appreciate the warm welcome and all the nice people here!

Talk to you soon,
Jamin

aumoore · #7 (**permalink**) 02-17-2003, 07:55 PM

Tom
IMHO some frames look kind of simple and week but you will find that most of the manufacturers use a version of a square tube ladder style frame including FFR which now has a simi-backbone frame that probably is not much if any stronger than most.

If I was you I would concentrate on what suspension the frame is designed for and how it is set up for that suspension. For example if you want a Live axle car than FFR now has a new three link that is supposed to be much better than the old mustang derived attachment. If you want a IRS suspension than you have meany choices like Ford IRS, Jaguar/Salsbury, Corvette and custom using a 9" ford rear chunk.

For my money you want a IRS rear suspension and you want one that allows the propler offset in the rear for the correct look. Most of the IRS suspension cars do this with the Everette Morrison being the exception. The EM uses a stock width Corvette rear so you need a positive offset wheel similar to a C4 or C5 corvette wheel. Great for handling but not for that cobra look.

If money is no object then the Kirkham is abuut the best overall Car out there. If you want a Jag style rear then ERA, Unique and Midstates are very good choices. If the Corvette suspension strikes your fancy then Hunter, Midstates are about your only choices for now as EM is currently out of business. If you want a Ford T-Bird derived IRS there is Superformance, RUCC, FFR, Backdraft and Hunter has done a few. If you are ok wiht a live axle then you have many possibilities: FFR, RUCC, B&B, A&C, and Shell Valley.

The live axle works pretty good if you have very smooth roads but lf you have real roads consider a IRS. Your backside will thank you and you can tell the differance around curves with a few ripples.

Excaliber · #8 (**permalink**) 02-17-2003, 08:26 PM

If your talking "handling" and "track use" there is no doubt who makes the BEST frame\suspension package.

JBL, end of story!

Ernie

Harris · #9 (**permalink**) 02-24-2003, 03:20 PM

Ernie,
I just happended to read your brief article on the advantages of round tubing over the square type originally used on the Caesar Type ll chariots. You of course are aware that Julius Caesar's top man was Marc Antony. But the guy that ran motor pool (actually chariot pool) was a fella named Pontius Cubealos. At that time they had been using square axles in all the chariots!

Many of the Roman legions went to battle in the square tube and square wheel type chariots. Caesar and Marc Antony's worker's compensation was driving them nuts-what with all the dislocated spinal vertabra and eposodic incidents of villusectomy, etc.
Marc went to Pontius and told him they had need of a better way to transport troops to battle. Pontius "the Cube" went to work immedaitely and in a few short weeks came out with the oblong axles we read about in the time of the Turkish invasion of Constantinople. The axles were a great improvement. However, as you can no doubt imagine the constant up and down, up and down, up and down motion generated by the oblong axles was making the Roman soldiers giddy,and somewhat sea sick. The soldiers tried driving slower and this didn't work. They tried going faster and this was even worse. The even tried "pusher" horses instead of "pullers". This was a terrible idea as they had no way of steering. This is where the term "bump steer" came from! Finally, in 603 AD they discovered "air ride" suspension and their problems were solved.
Glad to be of help.
Harris

Excaliber · #10 (**permalink**) 02-24-2003, 05:27 PM

Harris,,,was that bump steer or bum steer?

Ernie

PSB · #11 (**permalink**) 02-24-2003, 07:32 PM

If money is no object, and you want the best chassis for racing, go with JBL

Roger Upton · #12 (**permalink**) 02-26-2003, 01:13 PM

Saint

If you are wanting to race your kit you need to buy Herb Adams book Chassis Engineering. It is published by HPBooks - 1055. I purchased my copy at Barns & Noble. I use it to try and explain chassis engineering to people. Read chapters 7, 9, 11 and 12. You really need to read this book before purchasing a kit.

In simple terms take a ladder and grab one end and have a buddy grab the other and try and twist it then build a upper structure to it and try again. I single plane frame that is not honeycomb, can not resist twisting.
If you lay two frame tubes down then connect them with cross members, when you push up or down on one corner like the suspension would. You are now putting the main frame rails mostly in beaming strength not twisting. To have the main frame rail in mostly twisting strength you would have to have only one frame rail. Like one axle or one drive shaft. Round tubing resist twisting better than square or rectangular tubing and square or rectangular tubing resist beaming better than round. This is why NASCAR chassis have rectangular main frame rails and the roll cage is not only for driver protection but also chassis rigidity. That is way it extends from the front to the rear of the chassis.

Ideally you want your front and rear camber gain to be equal to body roll minus tire sidewall flex. You need a negative camber gain. Be sure to watch out for bump steer scrub radius. Also make sure the shocks and also the brake rotors are out of the way of heat from the radiator and engine.

Good luck with your kit.

Roger N. Upton

FIA#9 · #13 (**permalink**) 03-12-2003, 04:15 PM

For the $ the ERA is hard to beat. The frame is very important and I can give you some observations about the ERA: The frame is boxed and beautifully welded. It is very hard steel--can't use normal drill bits for long, it smokes em. NO cowl shake, flex, and if you try to jack up one corner you will soon find that 3 wheels are coming off the ground. I'm thrilled except the price stung the wife, but I just tell her its an illiquid investment that could be liquidated if we felt like it. (Don't feel like it, may never) Went to Shelby's factory last summer, came away knowing I had a better car.

auto10x · #14 (**permalink**) 03-21-2003, 10:20 AM

RUCC is strong and one of a few that use a backbone frams - - if you can get one!
auto10x

Leo · #15 (**permalink**) 03-21-2003, 01:52 PM

With your concerns in mind I believe RUCC is worth looking at. http://rawilson.net/cobra/rucc/ provides some info. Please do your research on the kit and the company before you jump in with both feet. Most of the manufacturers have specific forums that will provide a lot of insight as well. There are almost no bad choices!!