DAX or other & best chassis
Discussion
Ex-Biker said:
It was aimed squarely at the Python, ie. The car is not an established kit so will not have gained a reputation,[/quiote]
I thought that the python had a very good reputation (and can even remrber den said somthing on these lines on a thread on hear some where) so when i took over and took the project out of mothballs it was one of the best cobra kits ?
so why is it that it is now such a pile of stemming stuff acording to what you can read on this site ?
dont remember making a big steeming heap of a car yet (may be the Python will be my first? how knows) [quote=Ex-Biker]
I realise that you have been building cars for some time and as a company you have gained a reputation for customer service etc.
Not sure where all the "it must be bad untill proved other wise" is comming from (have good idear?)as you say i have only ever had a good reputation (untill know that is)so will just have to get this car back as soon as i can !!
kitcarman said:
Vince,
(if I understand it correctly) that you’ve seen an SVA certificate for a SUMO.
In your second response you say that the Viper weighed 1450kg and the old Python weighed 1400kg.
So, please leave aside Sumo’s, Viper’s and original Python’s and simply tell us how your car is going to weigh 400kg less than a DAX.
Simple question!Got a simple answer!
Den
AS always the red fog in your eyes stoped you reading what i said never said anything about Sumo at all!!!
and yes andy i am much better at cars than all this typing ,but im trying! carnt have it all one sided hey !!
SO den when are you coming over to see it all for your self ,you could come with Graham and test the demo car , be nice to see what you both write??
see no mention of looking at the Dax in Essex then ,Thought NOT !!still 32 hear
Andy
I was talking about the avarage big engine and full trim and all the bits not a rover ,as the one in the barn that i corner weighted (with your tool) was over 1300kg and no trim or side pipes !
the python body and chassis is around 180 to 190 kg so add the other bits and see what you come up with?as i know you are good at that!and the bm bits 425kg
regards Vince
>> Edited by vince rvd on Sunday 11th January 16:16
I was talking about the avarage big engine and full trim and all the bits not a rover ,as the one in the barn that i corner weighted (with your tool) was over 1300kg and no trim or side pipes !
the python body and chassis is around 180 to 190 kg so add the other bits and see what you come up with?as i know you are good at that!and the bm bits 425kg
regards Vince
>> Edited by vince rvd on Sunday 11th January 16:16
Can I ask why it's important to save weight on a Cobra replica ?
My Dax Rush is as light as I can afford to make it because it's going to spend 80% of its life thrashing up hills as fast as it can go, but Cobras aren't used to race are they ? (Yes, for sure the original was but I can't remember the last time I saw a Cobra on a track in the UK or Europe)
I wouldn't have thought it was relevent, especially with 400 lb ft of torque from a V8 at just over tickover
My Dax Rush is as light as I can afford to make it because it's going to spend 80% of its life thrashing up hills as fast as it can go, but Cobras aren't used to race are they ? (Yes, for sure the original was but I can't remember the last time I saw a Cobra on a track in the UK or Europe)
I wouldn't have thought it was relevent, especially with 400 lb ft of torque from a V8 at just over tickover
busa_rush said:
Can I ask why it's important to save weight on a Cobra replica ?
My Dax Rush is as light as I can afford to make it because it's going to spend 80% of its life thrashing up hills as fast as it can go, but Cobras aren't used to race are they ? (Yes, for sure the original was but I can't remember the last time I saw a Cobra on a track in the UK or Europe)
I wouldn't have thought it was relevent, especially with 400 lb ft of torque from a V8 at just over tickover
Dont know? I didnt even mention weight. Obviously its gotta be relative but as long as its in the right area its ok. As I originally said I just want it to be able to handle the biggest lump I can put in it well and not handle like a bag o shite.
Mainly its gotta sound ubelievable, have a fantastic paint job, be built with loving care, have a cracking interior and handle well. I dont really care if its 100kg more or less than the others. Fat difference that would make anyway as if i'm on my own its gonna be the weight of the passenger lighter and if i'm not its gonna be the weight of them heavier so thats at least 80-90kg either way before you start.
Still I find it enjoyable to watch everybody getting irate.
Weight of a chassis, like the torsional stiffness, will have an effect on the handling of the car.
As has been discussed before, torsional stiffness allows more control over the body movements to be conferred to the suspension rather than uncontrolled twisting of the chassis.
As I understand it, if you have two chassis with the same torsional stiffness, but different weights, the torsional forces applied to the heavier chassis will be "amplified" as the weight involved will be greater.
A heavier car will also be subject to a greater moment of inertia when cornering so a greater centripedal force will be required to get around any specific corner than a lighter car. Turn in will most likely be dulled in the same way.
As has been discussed before, torsional stiffness allows more control over the body movements to be conferred to the suspension rather than uncontrolled twisting of the chassis.
As I understand it, if you have two chassis with the same torsional stiffness, but different weights, the torsional forces applied to the heavier chassis will be "amplified" as the weight involved will be greater.
A heavier car will also be subject to a greater moment of inertia when cornering so a greater centripedal force will be required to get around any specific corner than a lighter car. Turn in will most likely be dulled in the same way.
There are a few posts on this thread that suggest that the GD chassis is stiffer than a dax ladder frame. GD makes much of the stiffness of its chassis design but, the last time I looked at their website, does not actually give a value. Nor does any other Cobra kit maker. Does anyone actually know the stiffness of any Cobra kit chassis?
busa_rush said:IMO which Cobra kit is the lightest isn’t the issue. The issue concerns all the advertising claims made in the promotion of this particular Cobra. This weight issue just happens to be simple because it’s not subjective. The Python is purported to be 400kg lighter than ‘a DAX’. Quite a claim!
Can I ask why it's important to save weight on a Cobra replica?
From January 2002 the Python has been advertised in Which Kit? in terms that categorically state that its handling is superior, its weight is reduced and its technology of construction is improved. These advertising claims are endorsed by Which Kit?, whose editor and publisher is employed by Vince in the capacity of UK sales agent/importer/salesman or whatever. My point is that Vince employs Fib’s who’s placed himself in what I believe is an untenable position. Certain obvious manifestations of this ‘relationship’ include the fact that Fib’s (10 magazines ago) recommended the Python as being best buy in the £10,000ish price sector.
It’s my case that this recommendation and the advertising claims upon which it’s based are questionable. If my argument prevails then it follows that the relationship that Vince shares with Fib’s is unhealthy for everybody in the Cobra replica industry (except Vince and Fib’s). Please forgive me if I appear determined on this point, so bear in mind that I was put out of business by Fib’s in the run up to this ‘unhealthy’ alliance.
The fundamental reason that I object to such claims is that Vince has not built a car. Because there isn’t a built vehicle in existence, Vince doesn’t know what it shall weigh let alone how it will handle. The matters as advertised are ‘hopes’ which, through Which Kit? magazine, are presented as ‘facts’.
This weight issue simply shows how Vince’s hopes and stated facts become muddled.
It seems that Vince believes (erroneously IMO
) that an original Python weighed between 1400 and 1600kg. It seems that he also believes (erroneously IMO) that a DAX weighs 1400kg. Apparently, he’s also spoken to other Cobra owners who endorse these estimates. On the other hand, it seems that Vince has calculated (probably correctly IMO
) that his Python will weigh around 1000kg. His (defective IMO) conclusion is that he can legitimately claim that his Python will be 400kg lighter than a DAX. The DAX, the old Python and the new Python all have a ladder chassis made from basically the same profiles of rectangular section steel tube and about the same amount of it. They must all therefore weigh about the same. Except the Python has an additional backbone structure running through its centre. Furthermore, all the Python chassis I’ve seen have been galvanized which is a heavy treatment. It therefore seems to me that, if anything, the new Python chassis is heavier than both DAX and it’s predecessor.
In respect to the body, the same arguments apply in that the new and old Python’s are moulded in the same mould. However the Python is 2” longer than DAX so presumably will be commensurately heavier. But it goes further than that. AndyCanham reckons you can stand on Vince’s fibreglass, whilst Vince reckons (high heels permitting) that it will take some ‘knocking’
. It very much sounds to me that Vince is producing heavier bodies too. Before I get accused of ignoring the foam sandwich ‘claim’, I will say that such construction is heavier and is only applied to certain areas of the body because it doesn’t lend itself to curvature. I know from experience that all current Cobra body/chassis kits weigh between 180kg and 240kg. If Vince has come up with a saving of 400kg on these figures, he’d better contact NASA
. He needn’t bother because he’s own estimate is within this range. It shall be interesting to see the reality, but as yet nobody’s seen
the new Python body in this country. Bottom line is that it doesn’t matter what it weighs because a V8 will push it along. I find the debate interesting because it shows what Vince doesn’t know. Others have indicated that the real issue concerns how it shall perform. The jury
is still out on that point. Den
Vince
I really don't want to get into a tit for tat bickering match. I had hoped you saw my posting for what I consider they are - unbiased observations.
I have deliberately tried to avoid the stuff from previous threads in a hope that funkyboogalooo gets the answer to his question.
I have no doubt that you do build good cars. Andycanam would not IMO buy a kit car that he did not believe in. You have made claims about your Cobra rep in previous threads and the summary I felt was that we would all be waiting for an independent review. I believe it was me that suggested Graham Bell, as he has no allegance with any of the magazines.
I like your idea of Den testing it at the same time. Remember Den's problem is in the way your car is being advertised, not necessarily how it's built. Yes he queries some of your assertions of the car, as would many others as the car has not yet been seen.
funkyboogalooo
I apologise that your question has been hijacked. Here is some info that may help get it back on track.
Other than the companies mentioned already:
Garner Douglas, Dax, RV Dynamics(Python), Pilgrim, Magnum; here are a few other companies that make Cobra reps:
AK Sportscars
Fiero Factory
Hawk Cars
L&B Cars
Madgwick (SRV8)
Has anyone got anything good (or bad) to say about these or others?
I really don't want to get into a tit for tat bickering match. I had hoped you saw my posting for what I consider they are - unbiased observations.
I have deliberately tried to avoid the stuff from previous threads in a hope that funkyboogalooo gets the answer to his question.
I have no doubt that you do build good cars. Andycanam would not IMO buy a kit car that he did not believe in. You have made claims about your Cobra rep in previous threads and the summary I felt was that we would all be waiting for an independent review. I believe it was me that suggested Graham Bell, as he has no allegance with any of the magazines.
I like your idea of Den testing it at the same time. Remember Den's problem is in the way your car is being advertised, not necessarily how it's built. Yes he queries some of your assertions of the car, as would many others as the car has not yet been seen.
funkyboogalooo
I apologise that your question has been hijacked. Here is some info that may help get it back on track.
Other than the companies mentioned already:
Garner Douglas, Dax, RV Dynamics(Python), Pilgrim, Magnum; here are a few other companies that make Cobra reps:
AK Sportscars
Fiero Factory
Hawk Cars
L&B Cars
Madgwick (SRV8)
Has anyone got anything good (or bad) to say about these or others?
doesn't lock this one. 
YHM letting it go MOVED ON !!
just dont want you all to get a very one sided view ? and the weight thing has been covered above,and from dens post he never see the red body at stafford 2002 as that was where i met the sri lanken and he was so imprest !the rest is history!
>> Edited by vince rvd on Monday 12th January 01:34
>> Edited by vince rvd on Monday 12th January 14:56
>> Edited by vince rvd on Tuesday 13th January 01:35
just dont want you all to get a very one sided view ? and the weight thing has been covered above,and from dens post he never see the red body at stafford 2002 as that was where i met the sri lanken and he was so imprest !the rest is history!
>> Edited by vince rvd on Monday 12th January 01:34
>> Edited by vince rvd on Monday 12th January 14:56
>> Edited by vince rvd on Tuesday 13th January 01:35
Ex-Biker said:
Other than the companies mentioned already:
Garner Douglas, Dax, RV Dynamics(Python), Pilgrim, Magnum; here are a few other companies that make Cobra reps:
AK Sportscars
Fiero Factory
Hawk Cars
L&B Cars
Madgwick (SRV8)
Crendon Replicas
For more, see Madabout Kitcars
funkyboogalooo said:
I didnt even mention weight.
I think you're right that absolute weight is not really the main concern of the average Cobra kit builder, nor should it be as with a throbbing great V8 engine you're guaranteed a good power to weight ratio.
However if you've decided to fork out on a Cobra, it's worth getting the best chassis you can for your money. In spite of contributing to what became a bit of a weight row, my personal view is that the lightest chassis is not necessarily best in this case, but rather that a rigid chassis is the most important thing, even at the expense of a bit of extra weight. Nothing will spoil your enjoyment of the car more than a floppy chassis and with hundreds of bhp under your foot you don't really want unpredicable handling.
As has been pointed out, there doesn't seem to be much in the way of available data from the manufacturers as to the torsional rigidity of their chassis, so the best thing you can do is make your own subjective assessment based on trying them (there are worse jobs!)
So to try and keep this thread moving in a positive direction, what engine are you thinking of going for?
Chris
(Tuned Rover engine but beginning to wish I'd gone for a 351ci Windsor)
You can have light and rigid with the right design.
Mike Broad of Magnum Engineering says that one of their spaceframed chassied cars with small block Ford V8 can weigh as little as 900kg (that might be dry weight) in road trim.
That same chassis will also handle 500+bhp big blocks, with one such car being in the workshop when I visited for totalkitcar.
Wouldn't advise going over the top on power for a road car though, because according to Mike's assistant, that big block car (built for a European race series for which cars have to be road legal) is crap to drive on the road.
Mike Broad of Magnum Engineering says that one of their spaceframed chassied cars with small block Ford V8 can weigh as little as 900kg (that might be dry weight) in road trim.
That same chassis will also handle 500+bhp big blocks, with one such car being in the workshop when I visited for totalkitcar.
Wouldn't advise going over the top on power for a road car though, because according to Mike's assistant, that big block car (built for a European race series for which cars have to be road legal) is crap to drive on the road.
Mark,
I don’t see this as ‘bickering’
and I don’t think the matters being discussed are likely to upset PetrolTed either, because nobody’s being insulting, save for my reference to ‘hot air’ and Vince’s to ‘the red fog in your eyes’. I believe Ted would regard such light-hearted taunts as acceptable in the cut’n’thrust of this debate which is now serious and to the point.
It seems that Vince has accepted that his claim that his car weighs 400kg less than a DAX was wrong. However, in my previous post I explained why I believe that he’s also wrong in asserting that his car is any lighter than its predecessor. Indeed, I explained why it seems to me that it’s very probably heavier. The fact is that, with the best will in the world, he doesn’t truly know the weight of either the previous Python or his new Python (because he hasn’t finished one
).
I’ve had a look at the SVA figures concerning which Vince asked certain owners. The certificate records GVW.For those who don’t know, GVW is gross vehicle weight including full charge and maximum load. One would expect GVW to be approximately 250kg more than curbside (or unladen) weight. I’ve a copy SVA test certificates for a Sumo V6, 2800cc and a GD V8, 5700cc. Both state GVW at 1250kg.
Big deal – I can hear some of you saying. He’s mixed up – not misleading. However, the basis of Vince’s advertising is that ‘Performance is higher, handling is better’. The major basis for those claims is to be found in the assertions concerning the ‘construction of the body and chassis – both are now lighter and stronger.’
Any fool can make a chassis lighter at the sacrifice of strength. However, to make a chassis lighter and stronger is very difficult. In fact I believe it’s impossible without changing the basis of the design (from ladder to space frame for example). However, that’s exactly what Vince has been claiming for the past two years. He’s obviously very clever, or very . . . .
The last thread was closed after Vince and I had a difference
of opinion concerning the torsional strength of his new chassis which relates to his ‘handling is better’ claim. Now we have a difference of opinion on this weight issue which directly correlates to his ‘performance is better’ claim.
It’s all very well and good Vince saying that he wants to put the weight argument behind him, but he’s presumably very happy to continue making the above advertising claims. I think that’s very wrong.
The CAP (Code of Advertising Practice) makes very clear that any advertised claim must be supported by documentary evidence before such a claim is made.
It’s very clear to me that after 2 years Vince still hasn’t got evidence concerning either weight or strength of either the old or the new chassis. I think that somebody
ought to ask the ASA
to ask Vince to justify these two claims. Whilst they’re at it, they should ask why a picture of a 13 year-old kit is being used to advertise a new (as yet incomplete) kit. All that is required is that the ASA on-line complaints form be completed.
www.asa.org.uk
It’s simple!
Den
I don’t see this as ‘bickering’
and I don’t think the matters being discussed are likely to upset PetrolTed either, because nobody’s being insulting, save for my reference to ‘hot air’ and Vince’s to ‘the red fog in your eyes’. I believe Ted would regard such light-hearted taunts as acceptable in the cut’n’thrust of this debate which is now serious and to the point. It seems that Vince has accepted that his claim that his car weighs 400kg less than a DAX was wrong. However, in my previous post I explained why I believe that he’s also wrong in asserting that his car is any lighter than its predecessor. Indeed, I explained why it seems to me that it’s very probably heavier. The fact is that, with the best will in the world, he doesn’t truly know the weight of either the previous Python or his new Python (because he hasn’t finished one
). I’ve had a look at the SVA figures concerning which Vince asked certain owners. The certificate records GVW.
For those who don’t know, GVW is gross vehicle weight including full charge and maximum load. One would expect GVW to be approximately 250kg more than curbside (or unladen) weight. I’ve a copy SVA test certificates for a Sumo V6, 2800cc and a GD V8, 5700cc. Both state GVW at 1250kg. Big deal – I can hear some of you saying. He’s mixed up – not misleading. However, the basis of Vince’s advertising is that ‘Performance is higher, handling is better’. The major basis for those claims is to be found in the assertions concerning the ‘construction of the body and chassis – both are now lighter and stronger.’
Any fool can make a chassis lighter at the sacrifice of strength. However, to make a chassis lighter and stronger is very difficult. In fact I believe it’s impossible without changing the basis of the design (from ladder to space frame for example). However, that’s exactly what Vince has been claiming for the past two years. He’s obviously very clever, or very . . . .
The last thread was closed after Vince and I had a difference
of opinion concerning the torsional strength of his new chassis which relates to his ‘handling is better’ claim. Now we have a difference of opinion on this weight issue which directly correlates to his ‘performance is better’ claim. It’s all very well and good Vince saying that he wants to put the weight argument behind him, but he’s presumably very happy to continue making the above advertising claims. I think that’s very wrong.
The CAP (Code of Advertising Practice) makes very clear
that any advertised claim must be supported by documentary evidence before such a claim is made. It’s very clear to me that after 2 years Vince still hasn’t got evidence
concerning either weight or strength of either the old or the new chassis. I think that somebody ought to ask the ASA to ask Vince to justify these two claims. Whilst they’re at it, they should ask why a picture of a 13 year-old kit is being used to advertise a new (as yet incomplete) kit. All that is required is that the ASA on-line complaints form be completed. www.asa.org.uk
It’s simple!
Den
Den,
That was nearly an interesting thread for a bit, but as ever, you've veered off into another of your personal tirades against the dark forces led by you-know-who!
When will you realise that as long as you have your own vested interests (which you clearly do) your self-appointed industry regulator status doesn't wash anyway.
I've said it before, your posts can be really informative but why not drop the crusade-like approach?
So, to try again to get the thread back on track, what engine do people reckon is the best choice in a Cobra replica?
Chris
That was nearly an interesting thread for a bit, but as ever, you've veered off into another of your personal tirades against the dark forces led by you-know-who!
When will you realise that as long as you have your own vested interests (which you clearly do) your self-appointed industry regulator status doesn't wash anyway.
I've said it before, your posts can be really informative but why not drop the crusade-like approach?
So, to try again to get the thread back on track, what engine do people reckon is the best choice in a Cobra replica?
Chris
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