Im looking for a gt 40 kit

[Hershal Byrd]

There is a secret to finding the best GT40 Replica. So I guess I'll be the one to expose the secret.
The secret is ...........DO YOUR OWN RESEARCH ON ALL MANUFACTURERS YOU CAN FIND. (was that loud enough?) /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif Then from that research you pick the one that best fits your needs and your budget. There is room out there for all of these manufacturers. They are in the business to make a buck but all of them love this car, and they all try to put forth their best. I also belive that all manufacturers will listen to honest critisism. If they truly see a defect in their product and did nothing I/m sure it would spread like wild fire. It's the company that jumps in and corrects this that stays around the longest. So there you have it, the secret of finding your dream with the most perfect tool of all..The search feature on this site. Use this in conjunction with all your other research and you can make one educated decision.
Everybody on this forum that owns a GT40 has the best one cause that's what suited them when thy made their decision.

Hersh /ubbthreads/images/graemlins/smile.gif

 

[Mike Dozier]

Hersh

Your suggestion would seem self evident...but it won't stop
newbies from asking the same question that get's the
membership so fired up.

I confess I have walked into certain stores
and simply asked for their recommendation without
doing any homework. I just hope they steer me right.
But for such a large investment as a GT40, you would hope
those truly interested would do more than listen to us.

MikeD

 

[Ian K]

[ QUOTE ]
Ian,

Creating an air of doubt is the issue. You have a gaggle of opinions based on speculation flooding the forum and there will undoubtably be those who are new to the GT40 scene (like Nic) take those opinions to the bank based on no evidence.

I can't understand why this is so difficult for anybody to understand. Hell if a 100 people said, in their opinion that it was ok for anyone to jump off a 100 ft cliff into a river (even though nobody has actually attempted it) and they'd be fine - and someone did and injured themselves is that responsible?

You know where I am coming from... I haven't seen any of the other manufacturers come under fire lately - seems MDA is the flavor of the month I guess.

Chris

[/ QUOTE ]

Chris, I understand where you are coming from. If you
remember, I have also come to MDA's defense elsewhere, and
even in this thread I have said perhaps Mark has designed
his frame in such a way that the crossmember is not
necessary.

However, your example of the 100 ft cliff and tirade against
people supplying there opinions is way off the mark. Your
example fails on 2 counts.

1) Common sense. I would like to believe thta 99% of the
members of this board would look at a 100 ft cliff drop
into a river and deem it unsafe without asking any opinions.
However, I would say that 99% of the members of this board
could not look at a bare chassis and evaluate its safety
on the road or on the track. That's where opinions come
in to play, and leads to:

2) Listening to the opinions of 100 people who have not done
something is different than listening to the opinions of
a half dozen or so people who have done something. This board
is filled with people who have been involved in the design,
building, production, and racing of GT40s and GT40 replicas
for decades (as well as other chassis). They may not produce
hard numbers, but they have real life experiences and as a
result, very valid opinions. Again, I will point out that
these opinions cannot be discounted wholesale, especially
considering the wealth of evidence in real life - the number
of manufacturers who do put the crossmember or other reinforcement
between the lower rear suspension mounting points. This
includes the originals.

Again, you may very well be right, and Mark's MDA chassis
has other design features that make the crossmember unnecessary.
And then apologies will come forthwith. I will also add that
I am not affiliated with any manufacturer, nor do I own any
particular make (yet). My shopping list is currently down
to 3 manufacturers, and guess what, MDA is still in the
running.

Ian

 

[Steve Toner]

[ QUOTE ]
Everybody on this forum that owns a GT40 has the best one cause that's what suited them when thy made their decision.

[/ QUOTE ]

I had the best one and someone stole it /ubbthreads/images/graemlins/frown.gif

 

[Trevor Booth]

Thanks Mark,
However there seems to be an air of uncertainty with the RF figure. Referring to the post you directed me to. The RF post states ""we were outside the tabulated results which stopped at 12000Nm/deg. We extrapulated (sic) the results and got the figure you stated above but I only claim the 12000Nm/deg"" Further on in the post the RF website is cited as claiming 20000 Nm/º.

Firstly- the ""we were outside etc etc "" statement is BS. There is no engineering basis on which you can extrapolate a torsional rigidity test.

Secondly- RF states that he has not done a TR test on a chassis with a full cage because it is very expensive. A certified TR test can be done in a day cost $AU2000.

Thirdly- The posted figure for DRB is correct. I have sighted the certified TR test.

Fourthly- there are enough photos on the forum to be able to put a DRB chassis "alongside" an RF chassis.
THREE TIMES AS STRONG ???

Fifthly- A torsion figure on a chassis alone is meaningless unless comparing chassis to chassis on the same basis and even then it will not give an indication of what a completed vehicle is. TR figures on a completed car ( or in the least a rolling chassis) is the true indication for comparison. One bare chassis may have exceptionally high TR figures but "weak" suspension mounting points and hence achieve a much lower TR figure as a rolling chassis.

Manufacturers should publish their certified test reports for all to see (rolling chassis) - but are they game enough I ask.

I am not knocking you or any manufacturer nor am I saying that one is better than the other, personally I dont care, but unsubstantiated claims are no basis for making decisions on which car to buy.

Everbody who owns an RF will say it is the best and likewise for any other owner. Who is going to admit that they made a wrong decision and should have bought "that car" because it is better.
You make your choice and pay your money.

Cheers

 

[Chris Duncan]

Torsional rigidity rears it's ugly head (again)

""1) RF has posted some very impressive torsional rigidity numbers.""

I was going to let this go but you repeated it twice in one thread. I sort of have to contest this information. I don't think the RF has as much rigidity as claimed, and it's not an independently verified claim. Just by comparing photos it doesn't have appreciably any more triangulation than some of the other tube chassis out there. I've argued this before and a rigidity test is easier than a dyno test but no RF owners seem interested in knowing the answer.

""2) Nobody else has (at least that I recall).""

Several have, just search "torsional rigidity"

Here's a thread that describes some do it yourself testing methods

HERE


I DARE any RF owner to prove me wrong.

Don't get me wrong though, the RF is one of the better cars out there, I'm just questioning possible misinformation.

 

[Hershal Byrd]

Trevor,
I know my RF is what "I" wanted so that's what I chose and was able to afford. At the time I didn't even know what TR was./ubbthreads/images/graemlins/grin.gif Now if "BEST" replica built barring price comes into the picture then I'm going for the Holman Moody MK II or one of the Sbarro replicas. Big money for sure and I sure as hell could care less as to the torsional rigidity of either one.
I have often admitted to not being the sharpest knife in the drawer but I do know how to read and try to better my self by learning a thing or two from folks like you and Kalun. Both of you gentleman appear to be very competent in you field. I wouldn't know where to begin to debate your opinions or if they even need debating. However I do hope that instead of calling someones post BS that you would at least give them the courtesy by asking them to explain their position or statement. I have tried to contact Robert and ask him to directly respond to these TR figures and get it squared away. He is not at home. I left a message. It is to the benefit of all that we offer up any engineering information that helps the consumer make a more educated choice.
Kalun, I don't care about proving people wrong. I would rather work out the problem and see how this really is supposed to be. I'm as interested as the rest of these folks reading this. I think it is by far more important to get the REAL facts out there. If you think that the statements about the RF's TR is eronious then lets see if we can remedy this by getting the correct figures by using your method or by having Trevor talk to Robert. Robert is also an engineer and I'm quite certain the two will get along great. They can also put their heads together and get to the bottom of this TR thing. I have no idea what a test of this nature costs but from what I've read it can't be much and it doesn't appear to be that hard to perform the test. I'm sure it will satisfy some folks out there that want to know.


Hersh /ubbthreads/images/graemlins/smile.gif

 

[Mike Dozier]

How important is maximum torsional rigidity to those who are not dedicated race cars? Is it more or less important to the handling characteristics than the right shocks/
springs/tires/wheels/brakes/roll bars/etc?
Would the "average" GT40 pilot be able to tell the
difference?

Compared to most Cobra frames I've seen, all the major
GT40 frames are way more solid looking.
Yet the Cobras seem to hold their own pretty well.

MikeD

 

[Ron Earp]

Just thinking of the five race cars I've driven (not many compared to many of you) in the last six months. I don't know what the rigidity of any of them are, but, I don't think any are as stiff as the GT40s being discussed. They are street chassis cars with good cages welded in and are more than stiff enough for racing duty. As Mike points out, I could much more easily tell which ones were heavy, light, 1/2 full of fuel, 1/4 full, had bad shocks, poor suspension geometry, good weight transfer, spring setup, etc, etc., etc. than I could tell "This one has a chassis that is 3x times more stiff than that one". Or "This one is 1.25x times more stiff than the other." I seriously doubt one could tell differences in stiffness of this magnitude.

I'm sure chassis stiffness differences existed in the different cars, but IMHO (there it is again!!!) how stiff it was wasn't as important as all of those other things. I suppose if it was a wet noodle it'd be instantly recognizable, but that is extreme.

I think I remember the show on the Ford GT construction saying that thing was at 22,000 N*m/degree. Or was it ft*lb/degree? At any rate, it is mighty stiff. As one member here has a GT and a CAV GT40 care to comment on stiffness of each car?

In the end I think discussing stiffness of our, uhhh, cars is sort of elementary bench racing - drive that thing. Not stiff enough for your track work? Do some design and start welding in supports. I'm sure any of the designs are plenty stiff enough for street duty and most track work.

R

 

[Chris Martino]

Hi Ian,

I never said people shouldn't post their opinions. This whole issue was not about defending MDA or bashing anyone's intelligence or wisdom. On the flip side, everyones opinions could very well be correct (ones own interpretation of information). I just find topics like this are easy for one person to take the pin out of the grenade and roll it down the isle, like yelling fire in a crowded bar.

It happens and you'll have stubborn SOBs like myself throw the grenade back-

In my opinion, I thought O.J Simpson was guilty.

This better be round 12 because my head hurts...and for the record, Nirvana would've been nothing without Dave Growl.

Just so you know - I love all of you guys - group hug.

xoxoxo

Chris /ubbthreads/images/graemlins/laugh.gif

 

[Ross Nicol]

Okay I will make my car available for these tests to be carried out, with 2 conditions.1/ An independent engineer carries them out. 2/ Someone else pays.I have a factory roll cage and the car has done 18 months hard racing. (could be intersting).
Ross

 

[Chris Duncan]

""How important is maximum torsional rigidity to those who are not dedicated race cars?""

It's like the foundation of a house, important but not a bling bling item.

""Is it more or less important to the handling characteristics than the right shocks/
springs/tires/wheels/brakes/roll bars/etc?""

depends whether you want those top dollar springs/tires/wheels/brakes/roll bars/ to really be used or not. Are they there for performance or just for looks? It's like a 500HP motor without a limited slip differential.

rigidity is the foundation of handling, without it you will never realize the full potential of the rest of the suspension system.

""Would the "average" GT40 pilot be able to tell the
difference?""

Not until you start pushing the car or if you're in an accident avoidance maneuver. You have to ask why the major manufactures all maintain a certain level of rigidity. I would think part of that would be safety in a extreme handling situation. I know Honda pays a lot of attention to handling and it's taken for granted they start with a rigid platform.

Do you want to race the car? If so you're not going to be truly competitive unless you have rigidity.

""Compared to most Cobra frames I've seen, all the major
GT40 frames are way more solid looking.""

I don't think any of the tube frame GT40 kits have max rigidity, mainly due to the door opening, it's an inherently weak design. The original car had the rigidity in the rocker boxes, you just don't see that duplicated in the tube frames.

"" Yet the Cobras seem to hold their own pretty well.""

In what type of comparison?

 

[Chris Duncan]

Basically what you're saying Mark, if we go by your figures, is that

this

is as rigid as

this

I knew I should have never got started with this thread

 

[Chris Duncan]

""Kalun's scratch built chassis doesn't appear to have a crossmember in the exact
place, but his tail end of the chassis seems closer to the
suspension pickups, so that might suffice.""

Due to the G50 bell housing there's no room for a lower crossmember directly between the lower arm inner pivot points. Unless you want to raise the engine/trans higher than the original design. So the frame is triangulated around that area.

"" Again, some results from him would be cool too, although he is not mass marketing it.""

The last test with all panels temporarily screwed in place put the chassis at 6,340 lbs/deg. at 375lbs fully sheeted. Not all that I was hoping for but in the ball park. It should be stiffer in the final test with full riveting/bonding of all the panels.

 

[Robert Logan]

Trevor,

I have just been phoned from the other side of the world about this e-mail.

I have repeated EXACTLY what my Registered Engineering Signatory has reported to me. I have all the supporting documentation at my work and would be happy to show you it if you would honour Roaring Forties with a visit.

My chassis and suspension and to that matter the majority of the engineering on my car has been designed and drawn by one of the finest RACE engineers in Australia. He has won Bathurst no less than 5 times and has a swag of other less important wins in Australia, the latest being the CURRENT Porsche GT3 champion engineer. He is simply one of the best engineers I have ever had the pleasure of meeting (I rate Carroll Smith above him as Ross does). I take exception to you calling my engineer Ross , my RES and myself liers. I stand by the figures that I have published.

Regarding costs, and $2000 for a retest with a cage, that is a lot of money to me and further more it is TOTALLY not needed. We have passed with flying colours the torsional and beam tests required to get my cars to be registered in Australia. Further tests would be a total WASTE of money and this monies would be my customers money. I am not prepared to do this.

As I said you are most welcome to my shop to see the information as discussed.

I am sorry for the tone of this e-mail but I have removed almost all of the real aggressive stuff.

It is good to show the "tall poppey syndrome" is still very much alive in Australia - you explain that one !!!

Best wishes,

Robert

 

[Robert Logan]

This is a hot one. I reply to one post and there are three more already there. Well I do type slowly and did do a lot of editing.

Responding to the photographs by Kalum.

The chassis is I think the "Factory Five " new coupe, please correct me if I am wrong.

There are many areas of weakness in this chassis and even with the cage welded in place these weaknesses will reduce the torsional strength. It is very difficult to comment much further as I do not know the type of material used or even the wall thickness. I could certainly strengthen the chassis as I am sure many others on this forum could, but is it necessary. What has the car been designed for and how rigid does manufacturer require it to be. I would also like to say that there are ways that I could further strengther my chassis. A V8 supercar here in Australia has over 30,000 Nm/deg I believe. I chose to leave the chassis alone when I got the results.

The reason I left it alone was my first car I built almost 30 years ago had an interesting tale of the handbreak. MkI did not work, MkII did and when registered MkVII was installed and I believe another 3 improvements had been discussed. The 18 month project had extended out to 5 years. I always remind myself of that saga and to this day have difficulty with procrastinators as I am sure they have trouble with my impetuous nature. (F&^* sake make a decission AGAINST stop shooting from the hip) Life is such a balancing act.

Saying all that, there are manufacturers who have put their products up for people to HACK away at and this is done. I believe that this is valid to some extent and people will quantify the ammount to them selves.

I made comments on other chassis on other threads but I was very careful NOT to condem them. I said that I believed the chassis would be fine for road use and would need some strengthening for raceing. I was also very aware that the chassis might not have been complete and did not want to coment on incomplete work.

The problem with this industry is that not enough consulting from EXPERTS in their own fields is done.

In Australia we have had a Cobra manufacturer (thankfully out of business) whoes engineering experience was as a fork lift driver. He designed his own chassis , flopped a mould and was an "expert" overnight. I shudder to think how many chassis he sold and how many peoples DREAMS were turned into sheer hell because of this. Thankfully the GT40 industry does not attract these types.

This is a great place to SOURCE information. This is why Ron , Hershal and myself got it going. I like getting things DONE that is why I do what I do. I am VERY pasionate about GT40's and very defensive about my own cars.

Please excuse my rambelings, I supose another half dozen posts will have been done by the time I click the send button.

Again

Best wishes,

Robert

 

[Trevor Booth]

Robert,
I did not call you or anybody else a liar.

I was not passing judgement on yours or anybody elses car/chassis/or whatever.

What is the figure 12000 or 20000 ?

You only need circa 6000 to register in Oz

You cannot extrapolate TR figures and if your RES told you that well ask him to explain how he did that for your own benefit. But I stand by what I said

It is not I who needs to see your TR figures it is your prospective clients. Post the test report on the forum for all to see and dispel any myths.

In the alternative you send one of your cars with full roll cage to me and I will to a TR test in accordance with the QUT procedure for free provided that I can post the test report in its entirety on this forum.

The tall poppy syndrome---Far from it I actually admire any body who has gone to the effort that you and other manufacturers have.

I note your second invitation to visit your works and as I advised some time ago I will attend next time in melbourne.

Cheers.

 

[Trevor Booth]

By the way Robert,
Whos seats did we try desperately to fit, whos headlight covers did we buy, whos window hardware are we going to buy. The only reason we did not buy your rear clip window was that it is glass.

 

[Russ Noble]

[ QUOTE ]
Hello guys and girls.
Ive been looking around for a gt40 kit for a while now and im in the process of deciding which kit i should buy.

[/ QUOTE ]

Wow, it's amazing that such an innocent question could light such an intense spark on this forum. /ubbthreads/images/graemlins/tongue.gif It's good that everyone is so passionate and serious and well informed about GT40's generally and that there are so many people out there with practical experience and professional expertise who are prepared to assist those that ask for help and also manufactureres and their representatives who do the same. That's what makes this forum such a valuable resource for anyone involved at GT40's. As always, at the end of the day you have to make a judgement on the veracity and value of the information received.

With regard to space frame construction principles, I have always found Costin and Phipps "Racing and sports car chassis design" to be an easily read and understood text on the subject.Although first published in 1961 the principles stiil hold good today.In motor racing where lightness and strength are prime requirements the pinnacle of the space frame design may have been the F1 Brabham BT26. I think this was the last succesful F1 spaceframe car. Any one interested in spaceframe design couldn't go wrong following the principles of construction utilised there. Since then some of the early F5000's were spaceframe, and Formula Fords, although smaller capacity and much more hitech in the suspension (or lack of!), are an example of a current well developed chassis. None of these I believe depart from the general approach outlined by Costin and Phipps. Anyone wanting an independent opinion on chassis design would be well served by getting a copy from their local library and studying it. There may be other, better, texts around and that being the case no doubt someone here will post them.

Regards

 

[Dan W]

My two cents coming from a 1st time replica builder:
Call current owners that are in different stages of completion (if possible) and get there take on the experience with the make of car they have.
Weigh that with all the gearbox/ car use etc,,, items mentioned in earlier posts .Personally check out the cars.
Once you take the dive and order a kit understand you will have disapointments /ubbthreads/images/graemlins/frown.gif They will come as no one has a perfect kit and I think most owners dont want to burn all the bridges with their manufacturer. I would bet there is lots of "tounge biting" on this forum from customers with all the manufactures.
/ubbthreads/images/graemlins/crazy.gif