What is the lightest "7"
Kerr205 - 22/3/15 at 09:41 PM
I've started to get a bit obsessed with this......I've read that Richard Meaden of Evo magazine fame built his own blade engined 7 and got
it down to 370ish kg and it got my thinking. What is the lightest kit and what is the lightest bike engine? Is 370kg the utter minimum that can be
achieved? Is this easy enough to achieve, I'm guessing not.
Just thinking whilst I'm idle!
daniel mason - 22/3/15 at 10:04 PM
Think the early blade motors In the caterhams were very very light as a package!
Kerr205 - 22/3/15 at 10:13 PM
I'm positive it was a Caterham and a blade that Meaden built.
Jon Ison - 22/3/15 at 10:16 PM
mines 440 with a bit of fuel, to get to 370 I would have to ditch the chassis and some..............
loggyboy - 22/3/15 at 10:23 PM
Westfield had the fw400.
400kg carbon tubbed with a k series.
not much point in getting much lighter unless you want it to handle like a matchbox car on a hard floor.
INDY BIRD - 22/3/15 at 10:34 PM
Video picking up a Caterham
https://www.youtube.com/watch?v=yAjl4TZdz_o
theduck - 22/3/15 at 10:35 PM
Even the light car company rocket was 380kg
daniel mason - 22/3/15 at 11:47 PM
The lighter the better! But the stripped out bike powered west fields at the top of the sprint tree are all just over 400kg! Around 405kg usually
ali f27 - 23/3/15 at 12:06 AM
all about power to weight and yes you can build a car at 370 kg
daniel mason - 23/3/15 at 12:13 AM
It would be tough! My force was 307 kg with no battery and tha carbon chassis only weighs a few kgs
Ugg10 - 23/3/15 at 07:38 AM
There were a couple of guys built r1 fury's fir the track only with lightweight chassis and paper thin bidies, those were reputed to be less
than 450kg. A while back sculptural engineering (built the elisealike larini which became the gtm ballista) were building a composite sandwich
structure seven chassis (think quantum extreme stainless chassis but in a carbon/fibreglass and structural foam sandwich). Don't think it saw the
light of day though, similar chassis have been used in formula student.
simonrh - 23/3/15 at 09:05 AM
quote:
Originally posted by Ugg10
There were a couple of guys built r1 fury's fir the track only with lightweight chassis and paper thin bidies, those were reputed to be less
than 450kg. A while back sculptural engineering (built the elisealike larini which became the gtm ballista) were building a composite sandwich
structure seven chassis (think quantum extreme stainless chassis but in a carbon/fibreglass and structural foam sandwich). Don't think it saw the
light of day though, similar chassis have been used in formula student.
Think this project is for sale on ebay at the moment?
http://www.ebay.co.uk/itm/BALLISTA-RACE-KIT-CAR-BODY-AND-MOULDS-/290956700477?pt=LH_DefaultDomain_3&hash=item43be5eeb3d
Ugg10 - 23/3/15 at 09:31 AM
Interesting, my only worry would be that you may have the moulds but do you have the rights to make and supply the cars (trade marks, copyrights,
intellectual property etc.).
I almost bought one of the first kits before opting for a fury. It has a similar design to the gtm libra. Composite sandwich monocoque with metal
frames front and back for the running gear. It was originally mk2 golf based iirc., vr6 anyone? The original designers, sculptural engineering, were
racing yacht builder I think and so that is where the grp foam sandwich structure comes from. The original demo car was very well put together, it
started out yellow, then was turquoise and I think it is now black and sold recently on ebay.
http://www.gtmdrivers.com/forum/ballista-body-moulds-for-sales-t2680.html
Back on topic - original advert for the SE Monocoque seven - stillborn afaik but great idea, would lover the time, knowledge and funding to develop
this idea.
[Edited on 23/3/15 by Ugg10]
coozer - 23/3/15 at 10:21 AM
Pretty sure that MNR had a race car built out of t45 that was 380kg?
MK9R - 23/3/15 at 11:14 AM
Ypu can make it as light as you want, but the question should be "what is the lightest structural sound 7 built"
Jon Ison - 23/3/15 at 12:44 PM
Just to clarify my post above, in no way was it intended to read that it cant be done, just that no way it could be done with mine.
jossey - 23/3/15 at 06:01 PM
mine was 410 kg with a bar but no cage, no fuel and only 1 seat.
Sam_68 - 23/3/15 at 08:16 PM
quote:
Originally posted by daniel mason
It would be tough! My force was 307 kg with no battery and the carbon chassis only weighs a few kgs
...although that's almost exactly 100 kilos more (nigh on half as much again!) than the claimed weight of the lightest hillclimb single-seater I
know of. 
gixermark - 25/3/15 at 04:00 PM
i had a road legal blade striker that was ~530-40 Kg, with full cage...
it had capri alloys.. and normal road bodywork, nothing fancy.. you could build one to 400Kg with thought and a few quid.
you could build a 36-380Kg 7, but for sure you would need to be creative... and spend a few quid
Kerr205 - 25/3/15 at 10:05 PM
Whoah, thanks for all the replies, I'm intrigued but this weight gain game.
K.
Chet - 28/3/15 at 01:52 AM
FYI-
My Hayabusa powered J15 weighs a confirmed 441 Kg on the road.
A well built R1 powered Riot should weigh considerably less.
It's amazing how strong and light a Jeremy Phillips designed car is.
Chet
Riot Squad - 1/4/15 at 05:20 PM
A bike engine Riot shouldn't have any problems getting under 400 Kg for sensible money. If you want to spend lots of money on Lipo batteries,
carbon fibre panels and body work there's certainly more weight to be saved.
A slight problem we have run into as the Riot is so light, is that for many race series we have to add a lot of weight to reach the minimums for regs!
perksy - 1/4/15 at 07:23 PM
Barneys blade engined Westfield was the lightest Westfield in the country iirc and was campaigned in the westfield speed series.
The attention to detail was superb and he had saved weight from every area of the car.
No problems with the handling and it certainly wasn't slow 
I'll have a dig and try and find out what it weighted, but iirc it wasn't alot over 300kgs
Riot Squad - 1/4/15 at 08:40 PM
A mid / rear engine car should always be lighter in theory than a front engine rear drive car due to the lack of propshaft, diff housing and
associated mounting hardware.
The Huff - 2/4/15 at 08:39 PM
My Fisher Fury with an R1 5PW lump weighed-in fully fuelled at 422Kg at SVA, 427 at last corner-weighting - has grown a Petty strut to the roll bar,
decent extinguisher etc.
Rather than worry about the car, I worked on me - upped the cycling & daily attitude etc to counter my increasingly desk-bound day job; and in
8months shed a bit over 18kg; target - 500kg for the car with me in it. 3yrs later I strive to keep it that way (I've currently got ~4kg to bin,
post-winter). Not all performance is about hp/tonne, 0-whatever - or requires buying more carbon! 
daniel mason - 2/4/15 at 08:56 PM
Pretty sure Steve marrs Saxon (if that's what sans refering too) is under 260kgs but that's unreal!
Sam_68 - 2/4/15 at 09:45 PM
quote:
Originally posted by daniel mason
Pretty sure Steve Marrs Saxon (if that's what Sam's referring to) is under 260kgs but that's unreal!
Yes, it's the Saxon I was referring to. I don't know if it's gained weight with middle-age spread (cars are as prone to doing so as
humans!), or how accurate the original figures were, but when first unveiled in the hands of Rob Barksfield it was quoted at 208kg.
But unreal in what way? Surely it just shows what can be achieved if you're really obsessive about weight saving?
Even lighter would be possible with a smaller, lighter engine...
You don't necessarily need carbon fibre and bottomless pockets, either:
It's probably unfair on the Force (and slightly disingenuous in an entirely truthful way) to point out that there's another hillclimb
single-seater out there that was knocked up in a domestic garage out of plywood and aluminium, with a car engine and gearbox, and built without
even benefit of power tools, yet still only tipped the scales at 266kg.
More realistically, plenty of Jedis are sub-300kg, even with 4 cylinder, litre bike engines and despite old-school steel spaceframe chassis. The
early, 2-stroke Jedis were well sub-300kg.
In that context, 307kg for a carbon-tubbed BEC single seater starts to look almost lazy. 
TimC - 3/4/15 at 06:07 AM
I think you'd get close with a Live axle striker with a basic roll cage and lightweight ali and GRP panels plus Braid/Force wheels and no
fripperies.
compturbo - 8/4/15 at 12:59 AM
quote:
Originally posted by Sam_68
quote:
Originally posted by daniel mason
Pretty sure Steve Marrs Saxon (if that's what Sam's referring to) is under 260kgs but that's unreal!
Yes, it's the Saxon I was referring to. I don't know if it's gained weight with middle-age spread (cars are as prone to doing so as
humans!), or how accurate the original figures were, but when first unveiled in the hands of Rob Barksfield it was quoted at 208kg.
208kg
daniel mason - 8/4/15 at 06:27 AM
Most jedis are over the 300 kg mark,and the SWB versions are tiny in comparison to the force! The penalty you pay for the attempted low speed
downforce is the weight of the huge wings and the mounting structure.
Almost all the carbon tubed cars are circa 300 kg with fuel and fluids on board,but some are just getting under that figure now! The new GWR 1100 will
no doubt be light but not seen any figures yet!
I've also just shaved around 6kg off the car so edging closer to the 300 mark
Sam_68 - 8/4/15 at 07:14 PM
quote:
Originally posted by daniel mason
Most jedis are over the 300 kg mark,and the SWB versions are tiny in comparison to the force! The penalty you pay for the attempted low speed
downforce is the weight of the huge wings and the mounting structure...
Yes, most (though not all) modern Jedis with their relatively large, 4-stroke engines are over 300kg, but not by much. When I were a lad, they had
350cc or 500cc 2-strokes, and you could tuck them under your arm and carry them home at the end of a day's hillclimbing.
But even these days and in stock, circuit racing trim, with a 1 litre engine, they're still only about 325kg, and that's with a steel
spaceframe chassis and relatively low budget, low-tech componentry. They're very much a single-seater analogy of the Sylva Striker, in that
respect.
But I think more than anything, it just demonstrates that if you're serious about prioritising low weight as a key design factor, then:
a) You need to be ruthless about everything else. It's no good saying that 'it's quite light for a big car with lots of
aero', because all that means, in absolute terms, is 'it's quite heavy'.
b) It's about more than just the chassis weight. The weight difference between the 208kg Saxon or the 249kg (wet lay-up) Megapin and the 300Kg+
Force is much more than the total weight of the chassis. You could make make the Force's chassis out of woven helium, and the car would
still weigh a lot more than the Saxon.
It takes more than a carbon tub to make a light car...
Similarly, and back on topic, the lightest seven chassis I know of (the FW400's carbon tub) was quoted at 45Kg. You'd have to come up with a
pretty inept spaceframe design to go much more than 75kg. So without getting silly (though, to be fair, it would be possible to design a tub
that's a few kilos lighter than the FW400, if you really tried) that's a maximum of 30kg to be saved on chassis weight. Any other savings
have got to come from somewhere else.
I agree with Tim that a Striker chassis with well chosen weight reductions in other areas would be the best bet for a really lightweight
'Seven' at sensible money.
... but am I the only person left in the world who doesn't break out in a cold sweat at the thought of driving a car without 30 kilos of climbing
frame bolted to it as insurance against an event that almost never happens? 
daniel mason - 8/4/15 at 07:27 PM
Without knowing the car it's very difficult to pass comment on it! Unless you do?
Anyway it's not been an 1100cc class car as it was 2nd place car (I think) in the Scottish hillclimb champs outright, behind the Gould of Ross
Napier, and had a 1000cc turbo motor installed before I bought it. Therefore the brakes are massive (and will shrink In time) and weight saving was
never much of an issue at 330kg and 300 RWHP of holeshot turbo behind the driver!
It will eventually break the 300kg barrier which again is not mega light compared to the Saxon which is actually 224kg but still very similar to the
the 300kg empires rolling out of bill chaplins workshop and breaking 1100cc records!
I'll be hopelessly slow though I imagine.at least until I get used to true single seaters after owning a truly lardy 470kg radical
Sam_68 - 8/4/15 at 07:41 PM
Nobody is disputing that heavier cars, with more power and/or more aero, can be very quick.
But that's not the point in question on his thread?
But we digress even talking about single-seaters. You expressed the opinion that a 370 kilo 'Seven' would be very difficult, on the basis
that your carbon single seater weighs 307kilos... my argument would be that your carbon single seater is a poor benchmark, because it isn't
that light in absolute terms.
I would be fairly confident that 370 kilos would be within reach of a very carefully specced 'Seven' (probably a Sylva derivative),
even with a conventional spaceframe chassis.
daniel mason - 8/4/15 at 07:56 PM
Fair point. But I don't currently know of any under 400kgs.
I know terry everalls westy is very well sorted,Planned,and specced. And covered in carbon and it's around 410kg I think
Sam_68 - 8/4/15 at 08:48 PM
Well, it is a wide-track SEi, which means it's physically a big bugger (I rattle round in one, and sylph like I am not!); probably +15
kilos on a Sylva, right there and then, no matter what else you do.
Then there's the full cage (25kg?).
The anti-roll bars and links (6 kg?)
Wide wheels (not saying they don't make it quicker, but they make it heavier, too)... pick a number, but let's be conservative and say a
kilo a corner; 4kg total?
We're at 360kg, already, and we're not even trying yet!
I think we're getting too used to 'Sevens' that have been built for big power, and beefed up to suit.
Food for thought: over half a century ago, the state-of-the-art in front-engined 'Clubman'-type road cars like the Lola Mk. 1 and Lotus 17 -
direct-line decedents of the original Seven - could weigh as little as 340 kilos, with a car engine and gearbox. Their steel spaceframe chassis
could be as light as 25-27 kilos (against 45kg for the Westfield FW400's CFRP monocoque and typically 70 kilos for a modern 'Seven'
type spaceframe, remember).
...and not a scrap of carbon fibre in sight.
daniel mason - 8/4/15 at 09:39 PM
Would you drive at speed in competition with a car who's spaceframe chassis has the same quoted weight as a modern roll cage? I wouldn't.
Like Austin said, you could make them as light as you want within reason but the chances are it wouldn't be safe. I'd also suggest a
striker,westy or s3 caterham would be the best bet for a lightweight 7
Sam_68 - 9/4/15 at 06:39 AM
quote:
Originally posted by daniel mason
Would you drive at speed in competition with a car who's spaceframe chassis has the same quoted weight as a modern roll cage? I wouldn't.
Yes, honestly I would, but I freely acknowledge that I'm not anything like as risk-averse as most people seem to be, these days - see my comment
above.
In over a quarter of a century of driving 'Seven' type cars, I've never had an accident serious enough to rely on on a roll bar (much
less a roll cage) or chassis impact strength to protect me. Its a therefore a risk that I, personally, find statistically acceptable.
Obviously, for competition there are other factors involved - the object is winning, and if that mean adding more weight to give you
downforce, sufficient chassis stiffness to make your big, grippy tyres work well enough, or whatever, then if it will make you faster, you do it. But
again, I think you risk confusing what's optimal for a particular application with what's possible.
sam919 - 9/4/15 at 07:55 AM
This is an intersting post, and ive chatted topics with Sam_68 before and i find you have become more amenable in the way you write :-), so
consqeuently i find your posts very interesting and full of historical reference also interesting!
Anyway, ive been down the route of 300bhp duratecs and big power, the trouble is traction, so now for my new project a CBR like Terry E is using, but
in standard form is the power source.
I need to achieve sub 400kg and with all the components needed to stop a heavier (heavier!!) 500kg car, this will be the start of the weight loss.
Currently the only things left from the 500kg/300bhp days are the chassis with wishbones and roll cage. The brakes are smaller/lighter, the fuel tank
is smaller/lighter, the wheels are smaller /lighter......etc etc.
As for the roll cage, it is the main component i cant really do anything about, its the double D superlight cage, and to be honest it will be getting
left the way it is.
So whats the lightest 7......if a road going Whiting 7 can be 390kg then a race one you would have hoped be lighter, ok it was a 919cc carb version
and live axle, but.....it has a dash panel, seat (i intend to use a foam version), more switchgear, paint! ali panels, ill be using carbon. If i get
390 ish but not over 400 ill be happy.
I feel the caterham 7 chassis which is a 2004 race item, is the lightest around and through numerous crashes over the years pretty sound in design if
checked and maintained properly
[Edited on 9/4/15 by sam919]
Sam_68 - 9/4/15 at 06:26 PM
quote:
Originally posted by sam919
I feel the caterham 7 chassis which is a 2004 race item, is the lightest around and through numerous crashes over the years pretty sound in design if
checked and maintained properly
For me, I think it would have to come down to whether I was building for road or race use.
The Caterham chassis is a lot heavier than the Sylva chassis (the best figures I have suggest possibly as much as 15 kilos), but it's also a lot
stiffer (possibly getting on for double the Sylva's stiffness).
For race use, on relatively stiff springs, it may well be worth the weight penalty. For road use, where you will want the lightest springs and damping
possible, to minimise skittishness over the bumps, ruts and potholes, chassis stiffness is much less of a factor (rule of thumb is that you need to be
aiming at a chassis stiffness at least 10x your spring stiffness, so lighter springs = lower target chassis stiffness).
Whatever, I think you'll still be fighting a losing battle against traction, 'cos with ultra-lightweight cars (particularly
those with no wings to give them 'pretend' weight), it becomes increasingly difficult to keep the effects of sprung:unsprung weight ratio in
check. Top-notch damping helps, but you can only defy the laws of physics so far.
sam919 - 9/4/15 at 06:56 PM
I didn't think it was that heavier.
The car will be a race car, I prefer something a lot softer and more comfortable for the road.
Traction won't be an issue trust me, even with the potential forced induction it may well get later on, we have proven winning 'tech'
behind the project as its an open class we race in.
Sam_68 - 9/4/15 at 07:49 PM
quote:
Originally posted by sam919
Traction won't be an issue trust me, even with the potential forced induction it may well get later on, we have proven winning 'tech'
behind the project as its an open class we race in.
I'm struggling to imagine how it can not be an issue, though, unless the winning tech is some sort of anti-gravity device!?
The bottom line is that, no matter how good your damping, the inertia of your unsprung mass hitting any surface imperfection has to be transmitted to
the sprung mass at a rate that would be damped out within, at most, 3 or 4 cycles of your suspension frequency. There's not much you can
do, beyond a certain point, to reduce your unsprung weight, so the lighter you make the car, the more that inertia is going to degrade its grip.
The Caterham's nothing special in terms of unsprung weight, with that big de Dion beam (or even bigger live axle) and outboard brakes, so
you're going to have a fundamental argument with the laws of physics?
sam919 - 9/4/15 at 08:05 PM
Think about F1 and its banned 'aids', even with limited regulation aero they still managed to get traction. I.e aero has nothing to do with
it.
sam919 - 9/4/15 at 08:13 PM
Also the s3 lightweight race chassis is much lighter than a standard westy sei chassis bringing it closer to your sylva chassis weight, according to
your above figures?!
Sam_68 - 9/4/15 at 08:27 PM
quote:
Originally posted by sam919
Think about F1 and its banned 'aids', even with limited regulation aero they still managed to get traction. I.e aero has nothing to do with
it.
Traction control?
Well, fine, but it only gives you the amount of grip you have at your tyre contact patch?
sam919 - 9/4/15 at 08:31 PM
And a whole lot more!
bi22le - 9/4/15 at 08:32 PM
quote:
Originally posted by gixermark
i had a road legal blade striker that was ~530-40 Kg, with full cage...
it had capri alloys.. and normal road bodywork, nothing fancy.. you could build one to 400Kg with thought and a few quid.
you could build a 36-380Kg 7, but for sure you would need to be creative... and spend a few quid
My 4age striker weighs 540kg with a normal half cage
Sam_68 - 9/4/15 at 08:35 PM
quote:
Originally posted by sam919
And a whole lot more!
How?
TimC - 9/4/15 at 10:54 PM
quote:
Originally posted by Sam_68
quote:
Originally posted by sam919
And a whole lot more!
How?
Elementary my dear Wat..ishetalkingabout?
sam919 - 10/4/15 at 05:24 AM
quote:
Originally posted by Sam_68
quote:
Originally posted by sam919
And a whole lot more!
How?
Electronics.
Sam_68 - 10/4/15 at 06:40 AM
quote:
Originally posted by sam919
Electronics.
Electronics just prevent the engine from delivering more power than the tyres can transmit to the tarmac. In other words, they don't give you a
'whole lot more' traction, they just allow you to make slightly better use of what's already there.
They can't possibly increase the amount of grip available at the tyre contact patch, which is basically a function of frictional coefficient and
the load (mass and aerodynamic) on the tyre.
Ye cannae change the laws of physics, Capt'n.
Ivan - 10/4/15 at 07:28 AM
quote:
Originally posted by sam919
quote:
Originally posted by Sam_68
quote:
Originally posted by sam919
And a whole lot more!
How?
Electronics.
One advantage I can think of is it allows full power acceleration to the legal limit without wheel spin attracting Mr Plod's or Mother
Grundy's attention. So one can use the power more often with less impact on your wallet or points.
sam919 - 10/4/15 at 07:51 AM
That's a good point but its just for race purposes so not road legal.
You dont need more grip if your using the grip you have efficiently, so electronics isnt needed to achieve more grip. Traction is being managed at a
very quick rate so it doesnt present an issue in the build,.... where putting power down is concerned, without defying the laws of physics/gravity.
Getting back to the topic, if the SEI chassis weight is 15kg heavier than a sylva and a caterham race chassis is lighter than a SEI but also 15kg
heavier than a sylva their seems to be some discrepency between chassis weight accuracy?
Does anyone know chassis weights that are accurate, and more so where weight savings could be made, i.e. the fins and extra perhaps un-needed alloy
around the diff housing 7" ford
[Edited on 10/4/15 by sam919]
Sam_68 - 11/4/15 at 08:59 AM
quote:
Originally posted by sam919You don't need more grip if your using the grip you have efficiently
You do if others have more grip than you and they're using it as efficiently, or nearly as efficiently. As with power in racing
it's impossible to have 'enough' grip.
With a very lightweight car, with the issues caused by sprung:unsprung weight ratio, I'd be spending my time and money on refining the damping,
personally, ahead of fancy electronics. TCS only helps you stop the driven wheels spinning in the limited situations when they have enough power to do
so. Good damping helps you everywhere.
Of course, you could implement full TCS/DSC/ABS, so that computers are managing the whole stability of the car, with (heavy, power-sapping)
pump-driven servos individually braking each corner to balance it but - again speaking personally - I'd see that as a bit of a hollow victory if
you achieved any success in competition. It's one thing optimising the car's performance, quite another relying upon computers to overcome
your limitations as a driver.
You might as well just buy a Playstation and save yourself the time and effort...
quote:
Originally posted by sam919Getting back to the topic, if the SEI chassis weight is 15kg heavier than a sylva and a caterham race chassis
is lighter than a SEI but also 15kg heavier than a sylva their seems to be some discrepancy between chassis weight accuracy?
Does anyone know chassis weights that are accurate
Getting accurate and comparable chassis weights is nearly as difficult as getting accurate and comparable weights for engines. You get into a whole
can of worms about the exact spec., what the weights include, etc., and after all that you'll still get bickering of the 'mine only weighs
so-and-so' sort, because there are production and assembly variations. Getting reliable and comparable figures for chassis stiffness is even more
difficult.
As best I've been able to determine, a bare Caterham road chassis and a bare Westfield road chassis are very similar in weight, but the Caterham
chassis is significantly stiffer. The Westfield has a separate lower bodyshell and is physically bigger overall, so total build weights tend to be
higher than the Caterham unless you're really obsessive.
I'd be interested to know where you're getting your figure of <15kg for a 'race' Caterham chassis, and the specification used
to achieve it, because the rules of the Academy, Grad and Supergrad cars all say you have to use a standard chassis, and there are ballasted minimum
weight limits - so no real incentive to reduce chassis weight at the expense of stiffness, even if you were allowed to do so. In fact, were you
allowed to do so (you're not, it's specifically prohibited), you'd add weight by using additional honeycomb and/or tubes to
increase the stiffness.
The factory 'race specification' for the chassis is a safety specification (ie. it adds items like honeycomb, roll cage and towing
eye), and hence increases base weight.
Doubtless you can get a 'lightweight' chassis built by Arch Motors, if you cross their palms with enough silver, but the same would go for
other 'Seven' type cars, Sylva and derivatives included.
quote:
Originally posted by sam919...where weight savings could be made, i.e. the fins and extra perhaps un-needed alloy around the diff
housing 7" ford
First and most obvious is to ditch the propshaft and separate diff... in other words, forget about a 'Seven' altogether, and go for
something mid-engined. The R1ot has surely got to be the lightest 'locost' ethos car, but if you're running in an unrestricted formula,
as you suggest, then you need to look in the direction of 750 Club Bikesports or RGB (clue: you won't find anything even vaguely resembling a
'Seven' at the front of the grid, these days).
After that, you should concentrate on unsprung weight first (and of that, the rotating bits) because that's what will give the biggest
improvement to performance and handling.
The Caterham de Dion actually has quite a crap rear suspension in terms of light weight, because it's heavily compromised by it's history.
The de Dion beam isn't the lightest solution (and make it lighter at your peril - they already have a propensity for cracking), and the bolt-on
Watts Link solution to the inadequacy of the original A-frame and trailing arm for modern levels of braking torque must have Colin Chapman spinning in
his grave (as must the 'superimposed' front ARB to overcome the limitations of the original ARB that shared duties as a wishbone link).
I've been accused of being anti-Caterham, in the past. If I am, it's because I think they're progressively engineering-out all the
Chapman/Lotus cleverness from the car with each modification they make to keep pace with the demands of increasing power and performance.
Other than that, is up to you. If you're serious, you need to be ruthless about every single component. Do you need it; can you make it do
more than one job; and after it's passed those two tests, what can you do to make it lighter?
sam919 - 11/4/15 at 09:52 AM
We were reffering to grip that i have in the car and if you cant use it efficiently then you dont need more, others grip isnt relevent otherwise you
just get another car the same as the one thats winning.
Traction control has proven itself to provide a quicker lap time than the rest of the field, its allowed and it a technical race as well as a driver
skill race.
Not sure where you get the sub 15kg figure from, this was reffering to your SEI 15kg heavier figure than sylva but the caterham chassis is lighter
than the SEi due to size, but in another breath its 15kg heavier than the sylva.
Comparing the 7 to current front rgb cars isnt a great example, things have moved on, RGB R cars use aero F cars dont so much, the current Arion by AB
uses a same layout as a 7 engine/prop/ driven wheel wise and it works well in its class, totally different to the R class.
The car i have is a caterham, agreed there are other options out their but this isnt what i have so ill be concentrating on this,and with a sub 400kg
figure easily done im not too fussed about the chassis i have i just need to reduce the wieght without cutting it up and putting single seater IRS and
componentry onto it example. caterham top ball joints compared to minuscule single seater items which would be 1/3-1/4 of the weight, its not
practicle, again i'd be better buying another chassis layout.
Anti caterham, doesnt really make much sense, things have moved on, its a piece of history but continues to have race success in it relative classes
when raced against the same layout of chassis and engine output. No use in comparing a Mk1 escort to a Ford Focus?
Bump and Rebound Protechs will be used and they have proven themselves against Nitron and all this black magic people want you to buy.
Excess metal i think needs to be reduced as you have said, there's nothing much more considerable so be lost, maybe different materials i.e.
plastic bolts where non structural etc pedal box cover bolts
daniel mason - 11/4/15 at 10:10 AM
Have you shortened the passenger footwell Sam? I'm sure you have done, this will pull the engine way back, reducing the length of the prop shaft,
diff wise, can the elite diff be retro fitted? I'd assume it's much lighter than the Sierra versions!
Sam_68 - 11/4/15 at 10:17 AM
quote:
Originally posted by sam919... the caterham chassis is lighter than the SEi due to size...
Where do you get this information?
As I stated above, the best information I have is that the current, bare Caterham chassis isn't significantly different in weight to the SEi
chassis, but that it's substantially stiffer (ie. its stiffness:weight is better, rather than its overall weight).
quote:
Originally posted by sam919...No use in comparing a Mk1 escort to a Ford Focus?
There would be if Ford fitted it with a 300bhp engine, welded some extra bracing and suspension links in place, then put it on sale as a replacement
for the Focus RS as a competitor to the latest Audi S3.
I wouldn't have a problem with Caterham developing their product to modern levels of performance if they did it in a way that way true to the
original Chapman ethos of light weight and low cost through cleverness.
My beef is that their solutions are conventional to the point of dull-wittedness, and I don't have much patience for dull-witted. 
sam919 - 11/4/15 at 11:22 AM
quote:
Originally posted by daniel mason
Have you shortened the passenger footwell Sam? I'm sure you have done, this will pull the engine way back, reducing the length of the prop shaft,
diff wise, can the elite diff be retro fitted? I'd assume it's much lighter than the Sierra versions!
Some good points Daniel. Yes the footwell is shorter ive just go to work on getting the engine further back, tbh i havent even tried as ive been busy
with building the garage is going in! also enjoyable but a large project.
I was thinking of using a subaru diff ?! its a lot smaller, and i would have hoped a lot lighter but i dont have figures yet.
Just size and weight Sam_68.
Caterham over the years have made better upgrades than just launching a newer engine and stiffening it with regards to the Escort/Focus example......,
materials have been changed, rear axle arrangment, wheel compositions and size, electrics, shocks and springs have been changed dependant on model
from the early cars. I think its slightly unfair to expect them to change otherwise having to try and keep the same caterham design and ethos, you
could say Morgan, TVR, Marcos are still the same in essense the only real manafacturer to push technical boundries has been Lotus with the Elise and
its chassis from a very vague point of view.
Caterham are still an easy car to work on and use mechanics most home enthusiasts can understand and tinker with. They demand a premium but what
company wouldn't use the kudos built up over the years to turn a profit, you cant find a morgan for less than 20 most of the time and they havent
changed a lot, infact not the nicest to drive either but they still have a following.
daniel mason - 11/4/15 at 11:35 AM
I think some of those elite duffs have changeable drop gears to alter ratios for certain circuits etc. And yeah, times move on just look at all the
tech in f1 now! And they can certainly get round a circuit in decent times!
Sam_68 - 11/4/15 at 03:08 PM
quote:
Originally posted by sam919
Caterham over the years have made better upgrades....
Well, that's where our opinions differ.
Apart from procuring better versions of third-party components as they become available (as you say, wheels, dampers, tyres etc.), and increasing use
of carbon instead of GRP, both of which anyone can do, the changes to the actual basic design of the Caterham have been pretty clumsy
and certainly not clever.
Better? Well, they addressed specific problems as and when they became too big to ignore, I guess, but not in an elegant or comprehensive way:
they're just quick-fix 'bodges'.
Their own excuse for the move to de Dion, which pretty much acknowledged that it's an inferior solution, was to say that they lacked the
resources to develop a proper IRS design... yet Jeremy Phillips, working near enough on his own in a shed in Lincolnshire, building a tiny fraction of
Caterham's numbers, managed it quite adequately. So did many others.
The CSR at least finally bit the bullet with a proper IRS, but even so, it's essentially a very conservative design: competent and safe, rather
than clever and progressive. Nothing that many other, much smaller, kit car manufacturers hadn't done before. Too little, too late to impress me,
I'm afraid.
quote:
Originally posted by sam919...you could say Morgan, TVR, Marcos are still the same.
Morgan now has two very distinct 'ranges'. Their traditional cars, certainty haven't changed any more than they have been forced to by
legislation, and keep all the hair-shirt limitations that appeal to dyed-in-the-wool flat cap enthusiasts, but I don't think you can say that the
'Aero' generation cars are still the same in design terms, by any stretch of the imagination: Elise-like extruded aluminium chassis
instead of steel ladder frames, modern wishbone suspension instead of sliding pillars and live axle... hell, they're even investigating hydrogen
fuel cells and diesel hybrids, working in conjunction with defence contractors and research universities! Despite the superficial '30's
pastiche styling, their engineering is actually becoming very progressive, for a niche manufacturer.
TVR and Marcos are both defunct. 'Nuff said?
We're drifting well off-topic, I know, but I think it's a valid discussion in the context of the thread, because my belief is that if you
want to achieve really big weight savings below 400kg, you'll need to take a more radical approach that trying to pare a few extra grams
here and there from an essentially conservative design.
AdamR20 - 24/4/19 at 07:03 PM
Bit of a bump this one, but I have something relevant to add. I've been beavering away in the workshop for the last 8 months or so and just
completed an early Narrow, Live axle Westfield with a CBR1000 engine and full FIA cage at 380kg wet (but no fuel). The chassis with a few alloy panels
was about 85kg, and I've added to that with a fair chunk of extra bracing.
There's no carbon, no magnesium, no titanium, no fancy alloy diff housing, just a heap of custom made parts which think outside the box a bit.
With a passenger seat, harness and road legal stuff (the chassis has a V5) it should still be under 400kg, just, so this target is easily possible if
you get your wallet out
[Edited on 24/4/19 by AdamR20]
cerbera - 24/4/19 at 07:40 PM
I was thinking about you when I started reading this post, lol.
Sam_68 - 24/4/19 at 07:56 PM
quote:
Originally posted by AdamR20The chassis with a few alloy panels was about 85kg...
Which is 40kg heavier than the carbon tub on the Westfield FW400 (and that could have been made lighter), so on paper, <340kg should be
easily achievable with a carbon tubbed BEC (especially if, like me, you're not a fan of full cages).
AdamR20 - 25/4/19 at 08:36 AM
Yeah, seems so.
Personally I think you'd be mad to drive a 500bhp+/ton car without a full cage though, IMO there's building a car chasing certain numbers,
and there's building a useful car; two different things.
[Edited on 25/4/19 by AdamR20]
Sam_68 - 25/4/19 at 09:10 AM
quote:
Originally posted by AdamR20
Personally I think you'd be mad to drive a 500bhp+/ton car without a full cage though, IMO there's building a car chasing certain numbers,
and there's building a useful car; two different things.
Well, each to their own.
Personally I think that a full cage increases risk in road use, unless you're harnessed in very tightly and wearing a crash helmet (in
which case, your visibility will be restricted by not being able to look over your shoulder effectively, which with the mirrors on a Seven makes you a
total liability to yourself and other road users). You're more likely to die by whiplashing a headbutt into a roll cage tube than you are to be
saved by it.
Cages are a good idea for circuit racing, a bad idea for road use, and probably irrelevant compared to a simple roll bar for hills and sprints.
I'm not aware of any accident on the latter where a full cage would have made a difference.
If you're that worried about risk, of course, you should probably stick to Volvos and Mercedes Benz.
FWIIW, mad or not, I drove one of the FW400's for several years, with just an aluminium rollover bar (one properly designed by its
ex-Lotus F1 chief designer), and I remain here to tell the tale.
AdamR20 - 25/4/19 at 09:29 AM
Good and fair points Sam! I like the idea of extra side impact protection with the full cage, quite important for road driving IMO.
sam919 - 25/4/19 at 10:06 AM
Slightly different although very similar underpinning as a 7 type car. I have a Mallock Mk27 and with full body on it weighs 354kg. The top cover is
carbon fibre and so is the rear wing. The chassis is made of 20mm ERW square tube, and its got a CBR1000 fitted along to an English axle with an alloy
nose (miuch lighter than standard cast). Other than that its 1983 engineering.
You've almost got to start from the chassis and scrutinise every part you put on, is it too heavy - can it be made of something different - is it
needed?
My caterham race car gained weigh due to having to upgrade and engineer more suitably rated components due to hikes in power, it ended up at 505kg
with a duratec and type 9 / 7" diff etc. You reduce the power and you can use lighter parts all round (seem to remember a guy using motorbike
discs and calipers!), but that's the re-engineering bit over making standard parts lighter.
It can get obsessive but it's interesting
https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwiCvvT6_OrhAhXvSRUIHSsNAQ
gQjhx6BAgBEAM&url=https%3A%2F%2Fwww.paddock42.com%2Fadvert%2Fmallock-mk27sg-rolling-chassis%2F&psig=AOvVaw3TrAhU7RaHIjF_WU_1I26k&ust=15562
72479521531
cossey - 11/6/19 at 12:37 PM
Wasn't the old Richard Miles striker at around 380kg (with the R1 engine)? His site went years ago but I've seen it mentioned by other
people.
I haven't seen anything lower but an early blade engine would shave a few more KGs off.
loggyboy - 11/6/19 at 01:04 PM
quote:
Originally posted by cossey
Wasn't the old Richard Miles striker at around 380kg (with the R1 engine)? His site went years ago but I've seen it mentioned by other
people.
I haven't seen anything lower but an early blade engine would shave a few more KGs off.
There is some achive of it:
https://web.archive.org/web/20160510105912/http://kerryandjane.com/index.shtml?section=striker&subsection=info
https://web.archive.org/web/20120305042849/http://www.btinternet.com/~richard.d.miles