Ultimate Seven Product
Discussion
Equus said:
bcr5784 said:
With a full set of Watts linkages on a de Dion tube the wheels move (practically speaking) vertically up and down on bump
Indeed.But the Caterham (unlike the Sylva, an example of which I owned for many years) doesn't have a full set.
It still has an upper wishbone, and a lower A-frame, and it is these that dictate the arc that the axle still describes.
bcr5784 said:
The reason the rear link is shorter than the front is simply that the rear link is attached to the rear of the chassis and you would have to make the car longer if the link was as long as it should otherwise be.
But you can compensate by varying the symmetry of the middle link, if you wish to do so. There are other clever variations on the Watts link, if you need to overcome packaging problems, too - the WOBlink, for example.bcr5784 said:
Why aren't they more commonly used? On mid engined race or road cars you generally cannot accommodate them because the gearbox gets in the way
That is what I'm talking about. Not sure what you are referring to as an "upper wishbone" there isn't one (not at the back anyway!)
However I come back to the main thrust - the De Dion works well, even without the Watts linkage (I think you'd have to be a real Westie enthusiast to argue that it handles better),
I am coming from the perspective that development often trumps theoretical advantage. Everyone would (I hope) agree that double wishbones are theoretically better than Macpherson struts - yet what is the best handling "sensible" sportscar - the Porsche Cayman (and the original Elan was damn good too). Semi trailing arms are a dreadful abortion - yet the Porsche 968 is very well regarded. Telescopic forks are a truly dreadful form of motorcycle suspension but have been developed to the point where all theoretically better arrangements have been tried and rejected even in MotoGP. I could go on.
If it ain't broke don't try and fix it - or at least fix the things that are broke (the worst drag factor of any production car allegedly) first. That is where they went wrong with CSR.
I'll end it there.
Equus said:
Sorry, ignore my reference to an upper wishbone - typing in a rush. I meant just the lower A-frame.
I disagree that they went wrong with the suspension design on the CSR... it's not especially cutting-edge, but it's competent and has a reputation for excellent handling combined with very supple ride which is very Lotus-like indeed (I marvel at this on the original Elans - of which I've owned 4 over the years - the Europa and the Elise). But I agree that none of the rest of the car really moved the game forward by much.
We do agree on fixing the things that are worst broke, first, though - aerodynamics, as you say, and chassis stiffness:weight.
Just to clarify I don't think there is anything particularly wrong with the CSR suspension (or even the modest, but welcome, aero tweaks to give reductions in front end lift and high speed understeer) - just that that wasn't (in my view) the most sensible focus of Caterham's limited engineering resources from a technical point of view - or, has been demonstrated, from a marketing one.I disagree that they went wrong with the suspension design on the CSR... it's not especially cutting-edge, but it's competent and has a reputation for excellent handling combined with very supple ride which is very Lotus-like indeed (I marvel at this on the original Elans - of which I've owned 4 over the years - the Europa and the Elise). But I agree that none of the rest of the car really moved the game forward by much.
We do agree on fixing the things that are worst broke, first, though - aerodynamics, as you say, and chassis stiffness:weight.
Don't really have a fundamental problem with mid-engines - owned and enjoyed a Europa S2 (yes I am rather geriatric) an Elise and currently have a Cayman - but nothing (other than perhaps a Radical) grabs me by the short and curlies and says "drive me" like a Caterham 7. And it seems - all things being equal - that a mid engined car is 6" wider than a front engined equivalant for easily explained packaging reasons - so I'd favour FERWD for British roads.
Equus said:
What easily explained packaging reasons?
There are plenty of mid-engined cars that are not excessively wide. Pertinent to a 'mid-engined Seven', I'd offer the Sylva J15 as an example:
But if you want something really tiny, there's the original GTM Coupe (Mini subframes, hence the same track as an original Mini... actually 6" narrower track than a Caterham):
And a bit of useless knowledge: the Fiat X1/9 actually has an identical front track to the Caterham.
Packaging. On a mid engined car you have to push the driver forward between the wheelarches to keep the wheelbase in check. You then have some difficult choices. There are plenty of mid-engined cars that are not excessively wide. Pertinent to a 'mid-engined Seven', I'd offer the Sylva J15 as an example:
But if you want something really tiny, there's the original GTM Coupe (Mini subframes, hence the same track as an original Mini... actually 6" narrower track than a Caterham):
And a bit of useless knowledge: the Fiat X1/9 actually has an identical front track to the Caterham.
1) Do you make the car wider so you can avoid an offset driving position and still retain a decent steering lock?
2) If you have a large central tunnel (Esprit/Cayman/Europa) you can't offset the driving position much so you make the car wider AND probably restrict the steering lock (Esprit, Europa)
or 3) make the car wider and keep a decent lock but bugger up Ackermann so you get a lot of tyre scrub (Cayman). The Esprit manages to to be humongously wide, have a dreadful turning circle and lots of tyre scrub - quite an achievement.
At the rear too the gearbox tends to get in the way of suspension components and tends to mean the rear track is quite wide (look at a Zenos)
I must admit I haven't driven (or sat in) most of the kit cars shown - but I'd be very surprised if they didn't suffer from some or all of the problems (the X1/9 certainly does) compared with equivalent front engined cars (with similar width wheels). eg the Elan S1 is 4ft 8" wide a Europa S1 5ft 4 with similar chassis construction. The Elise is probably the narrowest modern series production mid-engined car at 5ft 8" - which is definitely wider than I prefer and a Cayman is 5ft 10" and feels vast on the sort of country roads where the 7 would excel.
Equus said:
:cough: Bellhousing :cough:
Having recently designed a 'Seven'-style front engined roadster (prototype under assembly at the moment), I can tell you that intrusion of the gearbox, bellhousing and, in front of that, exhaust manifolds cause much more of an obstruction on a front-mid engined design than the wheel arches on a rear mid-engine one. Especially when your client insists on the option of using a Mazda 6-speed, which is a big lump, aft of the bellhousing, but that's another story.
I'm 6'0" tall and not lightly built. I struggle with the pedal box on a Seven, with my size 10 feet, but I've owned an X1/9 and was quite happy in it, and have driven a GTM without any issues.
We are not really comparing like with like here. Cars with full width bodies have more packaging options than 7-style ones .Having recently designed a 'Seven'-style front engined roadster (prototype under assembly at the moment), I can tell you that intrusion of the gearbox, bellhousing and, in front of that, exhaust manifolds cause much more of an obstruction on a front-mid engined design than the wheel arches on a rear mid-engine one. Especially when your client insists on the option of using a Mazda 6-speed, which is a big lump, aft of the bellhousing, but that's another story.
I'm 6'0" tall and not lightly built. I struggle with the pedal box on a Seven, with my size 10 feet, but I've owned an X1/9 and was quite happy in it, and have driven a GTM without any issues.
That said, I agree about the pedal box on a 7 - but it's no worse than a Europa S1 which is much wider - and there is plenty of scope to make it wider on the 7 without making the car wider with modest changes to the chassis design. Just making the whole thing wider a la SV isn't the way to go. Although we haven't touched on it before the 7 packaging is bad and could be much improved - the Elan (S1) is no wider (with the same size tyres - narrower than current 7s) and much better packaged. Any 7-style car (ie one without a "full width" body) is going to suffer in that regard. But any "Aero" 7 would surely have a full width body with a lot of scope for a decent pedal box without going any wider.
Re X1/9 it is 6" wider than an Elan of the same vintage and it's driving position was widely critised - but I can see that the width of the 7 pedal box will be an (as I say, fundamentally unnecessary) issue for many.
I also said that in order to shorten the wheelbase you (normally) push the driver BETWEEN the front wheels in a mid engined car. In this case they have chosen/had no option but to go for a longer wheelbase and put the driver behind the front wheels. Even vaguely mainstream mid engined car designers generally don't take that route and as I have explained (ad nauseam) the result is that in the vast majority of cases mid engined cars are significantly wider than their front engined counterparts.
Equus said:
No they haven't: the Sylva's wheelbase is 2,260mm (89"). The Caterham Seven's wheelbase is 2,225mm (87.6")... near as damn it identical, though I'm sure we'll now face several posts quibbling over the extra 35mm (1.4"), as if it couldn't easily be absorbed by other tweaks to the design, if necessary.
To suggest that they had 'no option but to go for a longer wheelbase' transcends absurdity: the R1ot is one of the smallest modern cars out there (as I said, narrower than the Caterham, by 3").
For what it's worth, the Lotus 23 places the driver's feet between the front wheels, yet still manages to be 2" narrower than the Caterham, too.
You're clearly determined to put up whatever spurious and lunatic argument possible to justify that the Caterham Seven cannot be bettered: that its antique chassis construction with its woeful torsional stiffness remains superior to anything we could achieve today, that (contrary to the evidence offered by every modern race car) de Dion remains the ultimate suspension solution, and now that its dimensional packaging cannot be matched by other configurations when quite demonstrably it can.
What have we got next? That the aerodynamics are unmatched, because no other car slows down as fast when you lift your foot off the gas?
I think you are being deliberately argumentative. I said "chose/had no option but" to go for a longer wheelbase. The Sylva has a VERY compact (transverse bike) engine and so it might be a reasonable to make that decision. Re the 23 - lock, tyre size vs CURRENT Caterham - and as I say 7 -style vs full width is ignored ? I have said there are a number of (potentially conflicting) compromises that have to be made and as you have implied there are compromises that a race car can make but are unacceptable on a road car.To suggest that they had 'no option but to go for a longer wheelbase' transcends absurdity: the R1ot is one of the smallest modern cars out there (as I said, narrower than the Caterham, by 3").
For what it's worth, the Lotus 23 places the driver's feet between the front wheels, yet still manages to be 2" narrower than the Caterham, too.
You're clearly determined to put up whatever spurious and lunatic argument possible to justify that the Caterham Seven cannot be bettered: that its antique chassis construction with its woeful torsional stiffness remains superior to anything we could achieve today, that (contrary to the evidence offered by every modern race car) de Dion remains the ultimate suspension solution, and now that its dimensional packaging cannot be matched by other configurations when quite demonstrably it can.
What have we got next? That the aerodynamics are unmatched, because no other car slows down as fast when you lift your foot off the gas?
And suggesting that I am suggesting the Caterham 7 cannot be bettered? For God's sake I suggest you read what I wrote!!! There is no point is arguing with someone who is arguing against points I haven't made or views I don't hold. I simply do not think that the route to a 7 replacement lies quite in the direction you do. Endof
Can we start again - you seem to be getting hot under the collar? I think (know) the aero of the 7 is crap. I know the packaging of the 7 is crap (though it does lead to low weight). I disagree that radical changes of suspension or even chassis design are going to yield significant gains (we will disagree - so what?) and I'm unconvinced that a mid engined solution will be better for a road car (we will disagree - so what). Can we just agree on that?
hufggfg said:
From my perspective, I think I'd agree with parts of lots of what has been said, but personally don't think a mid engine solution is right for Caterham, not for any particular technological reasons, but purely from a driving dynamics point of view. One of the biggest selling points (for me at least) with a Caterham is the adjustability at the limit, which in my experience is something that is not the same in a MR car. Maybe this is something that it is possible to engineer into a MR car, but I think the WAY it drives is key to a Caterham, not just the fact that it's very quick.
I have to agree - front mid for me too. That said I did drive one of the Radical Challenge cars and that was very benign and throttle adjustable at the limit - but then that doesn't have a heavy car engine behind the driver.Re EV, I really can't see that and I'm not convinced it makes any sense going down that route at this point in time. It would be heavy for a start and that is against the Caterham ethos. Sometime down the line when batteries become much lighter, legislation much tougher they might well be forced down that route.
cambuscat said:
CSR 620?
I get the feeling they have given up on the CSR - it's still available for sale (only the 260) but I can't recall when one was last roadtested. I'm sure if they felt that it would come out better in comparison tests they would continue to push it. Anyone know actual sales figures?Accepting that the CSR was an expensive solution - it's worse than that (Jim) - it was an expensive solution to a non- problem "ride". The focus of the design brief (according to Caterham at the time) was to improve the ride. Now I can think of lots of things which might deter people from buying a 7 - practicality, space, NVH etc etc but ride? I don't think so. With S suspension and comfy seats the ride is perfectly OK for the type of car it is. Other aspects of comfort may be lacking but ride is (can be) perfectly comparable with hot hatches and better than some.
Combine that with only minor aero and practicality tweaks (though welcome) and I can see why people were reluctant to pay the price.
Combine that with only minor aero and practicality tweaks (though welcome) and I can see why people were reluctant to pay the price.
Equus said:
Both Caterham and Westfield have lost the plot badly, in recent years, though, IMO. Both are surviving on their reputations, but the way forward is increasingly being led by other companies.
I'd agree that to some extent they are surviving on their reputations - but I'm not sure which other companies (operating in the same price bracket) are actually leading the way. Zenos and Ariel have their merits - but in terms of practicality they are way behind the 7 (neither has any luggage space) and no hood, and both have only just cottoned on that customers won't buy something without a windscreen (at least not in decent numbers), or, in the case of Ariel, that some bodywork is a good thing. Radical aren't in the same market. Zenos 11 or 12 might prove competitive but might not. Yes there are loads of kit car manufacturers out there, but commercially they aren't real competitors. Some are just producing cheaper but inferior 7s, others are producing some good - but very niche market - cars. Equus said:
If it comes down to Caterham needing to sell the Seven on the basis of greater practicality, they really have got problems...
Equus said:
I ought to say that I speak as someone who has owned and driven a Caterham as my only car, including year-round commute into a major city centre (Leeds).
And I speak as someone who has used a 7 as daily transport in all weathers over 10000 miles without hood or windscreen. But I realise that I am in a small minority of even Caterham owners - and I don't assume most others would regard that as acceptable. Other kit car type manufacturers (whether kits are available or not) seem to think that what is acceptable to them personally will be acceptable to their customers. Look how few Caterhams are sold sans hood and windscreen. It's not as if it's a cheap option. And yet both Zenos (what was Ansar Ali thinking?) and Atoms were introduced without either. To suggest that practicality at that level isn't important to people in the Caterham marketplace is clearly contrary to the evidence.
Equus said:
And yet Ariel are (literally) selling as many cars as they wish to build... how many manufacturers can say that, in the current market?
If they wished to build 10000 cars a year they wouldn't sell them. They may well be at capacity for the processes they use - but that is meaningless. It's a bit like when Morgan were assessed by JHJ and they were agonising over whether they could increase production from 8 to 8 and half (yes really) a week. tight fart said:
I used to do 50k a year without a hood or screen an loved every minute of it.
There's still a big market for motorbikes, but when you move over to a car you'd expect a little bit more protection.
I think we agree actually, because I think you may have missed my point - I used to drive 10s of thousands of miles on motorbikes in all weathers TOO - my point was that we are NOT typical Caterham buyers - but some kit car (type) designers think we ARE. Caterham buyers (at least the bulk of them) specify a windscreen and hood, and other manufacturers of that type of car need to take note.There's still a big market for motorbikes, but when you move over to a car you'd expect a little bit more protection.
Edited by bcr5784 on Tuesday 30th August 20:29
subirg said:
I love my Caterham and applaud the fact that it has stated largely unchanged for many many years. The world is littered with the dead remains of companies that innovated themselves out of business. I'm glad Caterham has avoided that trap.
I think those critical of Caterham (me too) do sometimes fail to take on board the fact that they have enthusiasts for the current car as is, that they have to satisfy too. It's the same issue Morgan have (albeit with a somewhat different ethos). Moving forward without losing their DNA really isn't that easyGassing Station | Caterham | Top of Page | What's New | My Stuff