Improving the Aero on my road car

[marcush.]

then there was not much in terms of parts count with the mini to start with.....
when I build my cars on dismantling everything goes over the scale including fluids etc.
btw the biggest single gain must be the battery for example.I ´m absolutely sure you will be amzed where the weight is really in this car...doesn´t it share a lot of bits with the normal smart?thinking of this i could imagine the ev smart may carry some lightweight componnents that could be a carry over...
sure the glass alround will stack up to something and can be halved by using pkastics-throw away the mechanism to lift and then look for the crash boxes ...two airbags and ancilliaries ....et voila the first 50 kilos gone.
btw change from steel to alloy wheelnuts=1 kilo saved on a five lug car! I can imagine calipers and brake discs as well -Elis MK1 had aluminium discs! that was light ...smart has iron calipers that alone should be a 10 kilo minimum loss.

or maybe this?
http://www.smartuki.com/

[andylaurence]

For a competition car, I can understand the desire, but the title of this thread clearly states road car, so I doubt the OP wants to strip it down to the bare chassis and rebuild it to lose a few kilos. I also doubt the airbags will be pulled out as they're normally a legal obligation on road cars, although if it's got the optional side airbags, they could save a few kilos if you're willing to remove safety equipment on a road car.

Back to the car itself, it shares lots of components with the Smart ForTwo, including the seats. They're part of the crash structure in the ForTwo, but not in the Roadster, hence why I immediately suggested swapping them out. You're right about the battery - a lithium pack would probably save 10kg (I saved 5kg over my Red Top lightweight lead pack in the ADR). Unfortunately, you won't save 50kg with window winders and windows. The windows are tiny, there's only 3 of them (plus windscreen) and they're thin glass already. Being frameless will present problems moving to Perspex. Many of the parts are plastic or aluminium. I didn't save 50kg when I pulled out the electric windows in a BMW 5 series and replaced them with Perspex.

With 3 wheel bolts, there's not so much to be saved, but clever selection of wheels would save a lot and you're right about the calipers being heavy, although the discs are only 9mm, so already quite light.

[marcush.]

I did not suggest two winow winders and glass saves 50 kilos...
but a thorrow march throu all and everything has considerable potential.It will be costly ,no question and it may ruin your idea of a legal car
I have no idea if those original rims do carry a lot of excess weight but of course everything is worth looking at..has the rodster mcherson front or the blade spring setup as early smarts ?

[andylaurence]

I suppose what I'm getting at is there are easier solutions that will net a good reduction in weight, rather than weighing half a dozen uprights to find the lightest and taking the car to pieces and putting it back together. Everyone's got limited resources and, as a club level racer, I realise that making appropriate use of those resources is what makes you fast. If it takes 200 hours to build a new diffuser, it's probably not as effective as making something that's close enough and only takes a day. It's the old 80/20 rule, whereby you get 80% of the benefit for 20% of the effort.

I know I could save 35kg by re-doing my bodywork in a lighter fabric, even more if I used a thin carbon pre-preg. However, it'd cost me a whole season's budget and I can achieve the same through other cheaper methods. For example, 5.5kg from machining holes out of my rear wing supports (cost = a few hours), 5kg from a lightweight lithium battery (cost = £50), 2kg by chopping off redundant body parts (cost = 30 minutes), 15kg from a lighter rear wing (cost = £300), etc.

To summarise, you're making good, valid points about saving weight, but I think they're perhaps not appropriate to making minor improvements to a road car. However, I'd like to thank you for posting, because you've certainly made me think about some things that could improve my car. Weight is key to my performance and I'd like to improve on the 65kg I've managed to lose from it in the last year (now 421kg). I've even started on a weight loss programme for the driver!

[marcush.]

I feel there is always opportunity to improve.
In my racing days i had the habit when dismantling the car for service i did not allow myself to add weight in any event other it was absolutely necessary.I got quite anal on this .and sometimes bits had to be added but then you aften found out you could safe some to compensate.
The most unewarding thing is holecutting into bdywork nethinks .Someone had suggested this and after hours of hard work it still was barely measurable effect....
I ´m a strong advocate of doing only things that net real benefits and efficient ones as well....so my thoughts are not to be understood as a workplan or whatever I have never touched a smart not even drove one..so I´m sure only digging into a muddy patch .
Worked a fair bit on elises and those had scope for a lot of weight saving still...so I´m sure there are some reasons for the small smart roadster to be a bit on the heavy side....even if they have a steel chassis ..but as i understand made of tailored blanks=weight optimised .