i know people go on about this,

but what advantage will i give?

i've just changed wheels and my new wheels are about 5kgs lighter eachwheel ( new ones weight is 4.7kg)

what difference will i see?

 

much better handling, unsprung weight just sits on the road with no control of how it reacts, bits that are always the same height and weight without weight shifting for better handling cause big problems.
you can't alter the car to accomodate how wheels work really, but you can tighten the shocks and stiffen the springs to make the shell move less, there is no give in unsprung weight.

probably not the best eplaination, but it's all positive.
the ideal is to have everything suspended on springs but this can't happen as contact is needed to the road on a rotating wheel.

 

Contrary to popular belief the main job (from a handling point of view) of your suspension isnt suspending the car, its keep the wheel in contact with the ground, less unsprung weight means less for the suspension to have to work against.

 

ah chip, that would make sense

 

cheers for that

 

would a difference of say 2.5kg per corner saving in unsprung weight be a noticeable improvement in handling on a mildly tuned road car?

 

No, just like losing say 30KG out of the spring weight wouldnt be noticeable on the road either realistically, anyone saying it would be is either a formula 1 test driver, or would also say a placebo made their car quicker, us mere mortals wouldnt notice it.

 

i'm looking to do a 1:10 around combe once these are fitted

 

You have more chance of getting picked for the harlem globe trotters.

 

i was actually on the phone to them a hour ago

 

Take that sunstrip off, you might achieve your 1:10 then only messing

 

I thought you meant how can you loose those chubby legs


Wheels im led to believe in being lighter will give benefit of
1) Making your wallet MUCH lighter.
2) Less energy will be required to accelerate the wheel.

Plimsoles help to! The lightest racing shoe on the market FACT

 

Every little bit helps as they say......personally i wouldn't bother with saving grams and the odd kilo here and there if you're not in some sort of race series with 1 make cars or something. Is it really gonna make that much difference against the massive variety of cars you get at trackdays?!

 

Power to weight WINS

 

firstly, if you saw my leg's you would see how far from chubby they are

Ł10 a wheel hardly hurts the wallet
and yeah, confirms what chip says above,

and power to weight is the only reason my car is mildly quick on track

 

I have been told that unsprung weight is like losing 4x's the amount of sprung weight from the car. Should notice a difference in braking and acceleration as less energy needs to be expended to move it. 5kg's per wheel is a good saving! Noticed a difference when changing to lightweight wheels on my car but that was 10kg per corner.

 

over on e30zone ive always argued against the "unsprung weight" argument when the bufties dismiss 17" alpina reps in favour of 15"bbs alloys. the difference is 17.5kg compared to 15kg, both with tyres. "they ruin the handling" etc etc.

 

You can get light weight wheels nuts aswell. Every little helps.

Andy

 

What wheels are they, C5 steels?

 

If you take 5kg off pr wheel, then it will eaquel to about 80kg inside the car ca.
unofficial you say 5kg x 4 = 20kg x 4 = 80kg inside the car.
2,5kg x 4 = 10kg x 4 = 40kg inside car etc etc
I got this from an ex F1 driver (old friend) , dont know how much you can use this off course, but seems right.
It´s rotating mass so better for acc and breaking

 

I agree with the weight argument but thats not the only thing that can ruin handling.

Escort turbos drive so much better on 16"s than they do on 17"s. They just do.

 

its a bit harsher due to the lower profile tyre but i prefer that. the rolling radius is the same.

 

yeah i spose.

but they just do i cant explain it.

 

I agree with them not just because the bbs are a much better quality wheel. Rep's are normally made of poor alloy. But the weight of a 17" tyre with a stiff sidewall is at least 10kg's so your weight doesn't add up. The 15" wheels will make the car more nimble and not as crashy as the 17's.

 

both wheels were weighed so theres no question of not adding up, thats what they were . an alpina rep with tyre and a 15" bbs also with tyre. there was a 2.5kg difference. my argument was that 2.5kg difference in unsprung weight would not be noticable on a road car.

 

Could be right weight wise just 7.5kg for a 17" rep is pretty light. Thing is the threads about a track car and 5kg per wheel WILL make a difference no doubt about it.

 

Something else i don't agree with lol, always ran with 15's and after swapping to 17's (lightweight oz superleggera's) i really don't find the car drives any worse. I use the car on road and track and if i'm honest the extra width etc helps with traction on track i find. Hear loads of peole speak about the difference between 15's and 17's on rst's being night and day but i've just never found that.

 

Remeber the 4x weight stuff is only for rotating components, wheels, brake discs, driveshafts, it doesn't apply to all the unsprung stuff, brake calipers etc