Jools

....and how much lighter is it than the standard UK spec Sti car. Have some plans to lighten the load on my Sti 7 with some serious carbon additions and have them painted. I can get all the carbon work done locally, so no probs there. Would loose the detachable type tow bar I fitted at the same time along with several other bits & pieces.

Any thoughts on this as a summer project...
Jools

jason4656

for 1 it has a totally stripped out boot, lightened glass supposedly in teh doors however from what i can see, it looks the same to me, no elec windows? although every one i have looked in had them, no air con, although the one i looked in had that too. Also the m3 csl has cardboard boot floor i think? not sure if you can do that too, might be worth looking how they did it, good luck

clubby

Jools

I would ask Iain Litchfield, he imports the Spec C so he should know.
www.litchfieldimports .co.uk

Just splash out and buy one instead!!
Contact details on his site.

SDB

Can't tell you the actual specifics of the C Spec weight savings, but it's a great project to do and incredibly worthwhile from a performance point of view - obviously check insurance, etc as there might be implications, but...

It is incredible what a difference you can make to the handling of a car by reducing weight, even small ammounts of weight, especially if it is high up.

It all depends how far you want to go... but if you wanted to go the whole hog (which you probably don't)..

Go for things that are above the centre of gravity first. Ceiling skins, sunroof, dashboard, windows, boot lid, bonnet, etc..

Then just go for anything you can after that..

I remember a MK2 escort project about 10 years ago, where a small set-up I was working with decided to make some weight savings to an already stripped out shell. They removed wiring looms, small bits of trim and carpet, bits of the dashboard, etc, etc.. all of which I though "what they HELL are they spending so much time on all this for??". To make a point, as they went through it, they put everything they took out in to bags, and eventually put the lot in a box. It was staggering to try to lift it and realise just how much weight had been saved by removing all those insignificant items.

Weight saving is one of the biggest possible performance enhancements on a car. It is a benefit in just about EVERY area of the car's performance.. The only major negative is the change in sprung / unsprung weight ration, but lighten your wheels at the same time, and you'll make that even better anyway.

Cheers

Simon

greasemonkey

The main area for weight saving on the Spec C is the removal of the big subframe underneath the engine. Beyond that, as Jason says, it's thinner glass, think the rear arms are aluminium instead of steel, aircon deleted, loads of little bits here and there.

richie,7,RA,spec C

no fog lights + covers
no boot spoiler ,light w8 rear seats no boot linning wined down windows no hand rails sun visor

TonyBurns

iTrader: (3)

The weight of a Spec C MY03 is 1350kg, its a little lighter than a uk car but it also has different suspension and an engine and transmission oil cooler(s).
It saves weight by getting rid of all those heavy items like sound deadening, aircon, electric windows, central locking, it has a lightweight shell also with thinner panels but its still as strong as the normal STi (i forgot the 50ltr fuel tank but this is displaced by the 12ltr watertank in the boot )
These do (in 17 inch form) come with rear spoilers, brembo brakes, ebd etc, the 16 inch version is another 50kg lighter than this

Tony

johnfelstead

The wheels are magnesium, not Aluminium on the Spec C, which saves a large chunk in weight and redresses the wheel rate/spring rate issue. The 16" version has light steel wheels/tyres and lighter brakes, plus a lower spec interior, it also has no ABS and a lighter manual DCCD setup.

The USDM STi is based in a very major way on the 17" Spec C because they had to get the weight down for tax reasons asociated with the US Market rules. That is why it is sold without any audio equipment, with the lightweight shell and magnesium wheels, it just scrapes in with that lot.

ScoobyTal

are these magnesium wheels the same as the bbs wheels fitted to my jdm sti gl my03 ? (factory option with the dccd-a quick steering ect)

johnfelstead

these.

Danny B

Fancy putting the weights on the outside of the wheel
Sacrilege...

ScoobyTal

Thats them

S25 SRT

i remember top gear did a subject on weight saving...they stripped out a old xjs jaguar to next to nothing and the thing that surprised me was the times were only very slightly faster no really...ive considered it as im taking my rear seat out my type r but im probably not saving weight as im going to get my ice dealer put some carpeted mdf in its place so it does not look or feel so cold and looks tidy....

ScoobyTal

rear seat weighs naff all

S25 SRT

was only going to do it if i put a roll cage in, u cant get in my back seat anyway cause of 4 point harnesses.
im not worried bout weight saving, car goes plenty quick enough.
whatever floats your boat though,

pwebb

no-one mentioned the tiny battery and smaller washer bottle ;-)

that 6 speed gearbox is very heavy and doesn't help with low centre of gravity - I am surprised they didn't offer the spec c in a 5 speed version - as in the new legacy/b4 which was kept as 5mt to bring the weight right down - less than the jdm sti in fact.

Paul W

Jools

The car I have has the Prodrive wheels, springs, anti roll bar, drop links, anti lift kit, sti alloy strut braces, Sti titanium exhaust, Prodrive lights, etc. The bad thing is I fitted a detachable type Subaru tow bar to pull the Westy to Kncokhill, but I have a change of plan here and will loose the tow bar soon, not forgetting everything in the boot, spare wheel, etc.

I had already indented to remove the sub frame mentioned above (which was fitted for the American market after crash testing I believe) after I fitted the ALK kit from PowerSation. I could see then that the sub frame is only a bolt on piece anyway and my mate told me about the crash teasting. Does the Spec C have the under engine plastic covers I wonder and would it have a negative effect to take all that off as well I wonder.

My thoughts are to have the front and rear bumpers, side skirts, rear boot & spoiler and the bonnet, grill & scoop assy all made in carbon fibre. Maybe look at lightweight carbon seats as well. Been on my mind for a while and when you see the likes of BMW and Ferrari going to the lengths they do to shed weight there must be wisdom in what they do. If I go this way I will start with getting the car weighted properly as it is now with a full tank of fuel and then venture on a "spring" project and see what results there are to be had.

Jools

what would scooby do

..and don't forget that the driver needs to go on a diet to shed a few kilos

always catches me out when I wash my Type R - if I press to hard with the sponge the roof bends in LOL

LitchfieldImports

Best to speak to Curtis at Powerstation as he has taken all of my Spec C's and STI's apart for security systems and conversions. He is always pointing out differences and little bits of metal missing, its extensive

The USDM STI I had the other day had extra crash beams as well. oh and wider seats lol

Regards

Iain

[ur;]www.litchfieldimports.co.uk[/url]

SDB

Re the XJS not being much faster. Depends what actual test they did.

For instance, a long straight drag of about a mile would see very little difference, as you're starting to deal more with power / drag ratios rather than power / weight.

If it was a handling course, the driver will need to be able to exploit the benefits of the lighter car.

Would be interesting to know?

John.
What is the wheel rate / spring rate "issues" that the lighter wheels addresses?

Cheers

Simon

Andy S.

Weight is a big performance gain, as said before lower your weight and gain in all areas, acceleration, speed, braking and handling.
As a designer of lightweight single seater race cars I know the advantage. It is simple physic's realy the lighter it is the easier it is to move, change direction and stop.
As for the unsprung weights this annoys me that most manufacturer of wheels cant tell you what weight they are. We have our wheels manufactured from billet magnesuim centres with aluminuim rims and weigh in at 2.5kg's a weight saving of 1kg per corner on F3 rims. This is the way the rally teams get their cars lighter as well lots of magnesium titanium and Carbon fibre.
Still cant afford a spec C yet though.

S25 SRT

was driven before and after by the STIG m8...

johnfelstead

it was in referece to this you posted

Spring rates and wheel rates are not the same thing. You have to spec the spring so it can support the chasis and provide the correct ride height. You also have to spec the wheel rate so that the sprung/unsprung weight charicteristics are correct. You can alter the wheel rate by changing the suspension geometry, spring/suspension pickup points, to provide you with the most suitable frequencies. Changing the spring poundage affects these two areas in diferent ways.

ex-webby

S25

Thanks for the quick response

THe problem is.. there are many stigs. In addition, the conditions, can change as well.

But.. the fact that it WAS quicker, says something, and you it may be that the percentage difference in the car before and after is not as great as on many other cars, as the things weigh about 3 tonne anyway!

---

Andy, agreed re the lack of importance seemingly placed on wheel mass. It is also a travesty when people fit huge alloys to cars thinking it will improve the handling, but at the same time increase their unsprung weight, which is a direct negative with no positives.

It is an interestingly (almost) unique aspect of vehicle dynamics in that reducing your unsprung weight really does have no negative effects (apart from the potential of the wheel being less durable).

Cheers

Simon

Andy S.

Yes I know what you meen my sccob still runs on 16" for that reason, If I do ever change the wheels they will be mags or even Carbon if I can get them made!
Some of these wheels weigh a tonne, I borrowed a P1 wheel to model it in on the Cad system, and I was horrified at the weight of them.

So god knows what 18" and 19" Alloys weigh in at


[Edited by Andy S. - 1/30/2004 11:46:11 PM]

SDB

I think you've mis-understood john.

I was talking about the ratio between sprung and unsprung weight. Not the difference between wheel rate and spring weight.

Unsprung weight has a greater negative effect on a car's R&H the lower the wheel rate is in comparrison to the spring rate. But taking the same car and changing the unsprung weight has nothing to do with spring rate vs wheel rate.

If you assume that the spring rate vs wheel rate is the same (as it would be by just changing the wheels) the unsprung weight is something that can be qualified as an advantage to be lower.

Cheers

Simon

SDB

Andy

I don't know for sure, but I have a feeling that the P1 wheels, with tyres are lighter than the standard 16's with tyres. It means a really good wheel, but sometimes increasing the wheel diameter means less added weight than you lose through side walls.

But then again.. Everything is a tradeoff. Increasing the diameter, (obviously) gives you less sidewall flex in the tyres, which (depending on the surface and application) is a potential beneift, which is, in many circumstances, enough to outweight (excuse the pun) the disadvantages of a heavy wheel.

Don't you just love vehicle dynamics. It's all so straight forward!!

Cheers

Simon

akshay67

I don't want to take the **** here, but a suggestion is that if you are fat you may benefit from losing weight. Some times it may be easier to lose a few kilos of your body than to totally rip the consoles out of your car...

johnfelstead

Its not quite that simple.

One of the major areas relating to chassis performance is the profile and construction of the tyre. A large light wheel with a low profile tyre will give sharper handling than a small wheel with a high profile tyre due to smaller gyroscopic effects, even if the overall weight of the two setups is identical.

The 18" speedline flowformed wheels on my car are lighter than the 17" wheels i have, and with the lower profile tyres on the 18's that improves the situation even more. Remember the Rolling Radius is identical.

SDB

LOL

Absolutely. You don't see many podgy F1 drivers. Which is possibly why I haven't had any offers from Ferrari lately

Mind you.. being over weight does improve your sprung / unsprung weight ratio

Anyway, let's not turn a constructive thread in to a p*ss take?

Cheers

Simon