Where the weight comes from

[ExMX5]

Not choccy biscuits!

What makes the 1er such a heavy car - is it the chassis or just all the extras (like powered seats) that chunk it up?

Does it use a lot of sound proofing?

[Yep 135]

There is a chunk of balast in the back end to give it a 50/50 weight distribution. I dont know how much but its to even out the engine weight I guess.

[Alext]

The panels that BMW use are pretty thick and sturdy. Look at the bonnet for example vs the aluminium bonnet of a 01+ MX5. Dont BMW use something like 30kg of paint on a 3-series?

Also one of the headrests must weight what 20kg?

[grunt]

54% Iron
12% Nickel
9% Copper
8% Aluminium
6% Sulphur
5% Hydrogen
2% Oxygen
2% Cadmium
1% Chlorine

1% soul

[grunt]

oh - and when I'm driving - 12% idiot

[DTNJNQ]

The BMW is a fairly solid car compared to a lot of japanese cars. Also the weight is similiar to other similar sized cars. The WRX STi is 1505Kg

[BBK]

Is there much room for weight reduction? For one, I would probably ditch the subs under the front seats if you could.

[Yep 135]

Originally Posted by BBK

Is there much room for weight reduction? For one, I would probably ditch the subs under the front seats if you could.

lighter front seats, recaro etc,
lighter set of brakes, (ceramic ...nice)
lighter wheels,
smaller battery,
sports exhaust,
dont order the sunroof option,
cf bonnet and boot lid,
go on a diet and loose 10kg's (I need to do this)
All might be good for over 100kg saving.

[professor]

simply weighing two wheels and comparing across them is a very poor measure for their performance capability. a 13kg wheel can be better than a 8kg one if the distribution of weight in the former enables lower rotational inertia.

[Yep 135]

and then you have to brake!

[Yep 135]

Originally Posted by professor

simply weighing two wheels and comparing across them is a very poor measure for their performance capability. a 13kg wheel can be better than a 8kg one if the distribution of weight in the former enables lower rotational inertia.

What is better then, rotational inertia and/or more weight in the wheels or a lighter roof?

[professor]

rotational inertia is never better from the point of view of acceleration - my point was simply that the design of a heavier wheel can theoretically allow it to have equal or even lower rotational inertia than a lighter wheel. as far as the sunroof in most cars is concerned, i would say it is much less a weight related issue rather than a torsional rigidity one.

[AussieRacer]

Lighter wheels isn't just about rotational inertia (although it is a big part), a light wheel effects the responsiveness of the suspension, and normally for the better the lighter the wheel is.

[professor]

aussieracer, go on mate. how does wheel weight affect the responsiveness of the suspension? my guess would be damping frequency and linear inertia?? but then, wouldn't heavier wheels be less susceptible to toe angle change? explain please.

[larryn]

Think of the 135i as pretty much identical to a 335i, minus a 9" section of sheet metal in the middle. Once you look at it that way, and look at the 335i heft, you'll see why it weighs 3298lbs.

[Guran]

Originally Posted by professor

aussieracer, go on mate. how does wheel weight affect the responsiveness of the suspension? my guess would be damping frequency and linear inertia?? but then, wouldn't heavier wheels be less susceptible to toe angle change? explain please.

Unsprung weight! Same thing with the brakes. Both affect the way the suspension works. Unfortunately that ends my level of knowledge on the subject though.

[Guran]

Here's a good bit of background reading for you:

http://en.wikipedia.org/wiki/Unsprung_weight

[Yep 135]

Not only being just being lighter, having a lighter roof helps with body role a bit. Losing 10 odd kg's 1.2m high on a car = more stability.

[black135]

Originally Posted by larryn

Think of the 135i as pretty much identical to a 335i, minus a 9" section of sheet metal in the middle. Once you look at it that way, and look at the 335i heft, you'll see why it weighs 3298lbs.

I read somewhere that the 135 uses the same platform as the older generation 3 series not a smaller version of the current 3 series.

[professor]

guran, thanks for that link. it sort of reinforces what i was imagining in my mind when i mentioned damping frequency and suggests to me that beyond a point there seems to be less benefit in shaving off the mass from the wheels and more to be gained in tuning the suspension in conjunction with a given wheel weight. obvious stuff, but so much more fun logically deduced logically.

[mistermojorizin]

Originally Posted by black135

I read somewhere that the 135 uses the same platform as the older generation 3 series not a smaller version of the current 3 series.

i did too. that was circa 2007 though, before I knew the 1er was getting twin turbo 6 and could care less about the car. this was the best info available at the time as reported by motortrend and i'm sure other magazines.

anyway, what larry said is 100% accurate. what you and i read was some BS.

[ExMX5]

Originally Posted by professor

aussieracer, go on mate. how does wheel weight affect the responsiveness of the suspension? my guess would be damping frequency and linear inertia?? but then, wouldn't heavier wheels be less susceptible to toe angle change? explain please.

I believe the effect can be described very basically as having 4 gyros attached to your car - they resist changes in movement in just about every plane except the direction of rotation.

The wikipedia article is pretty good as well. wikipedia :wub: