Ivan
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 24/4/19 at 07:40 PM |
|
|
I was thinking about you when I started reading this post, lol.
|
|
|
Sam_68
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
| posted on 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
|
|
|
|
