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      04-09-2008, 03:12 AM   #1
dakulov
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Weight difference with different options?

I ve been wondering how much weight do the most popular options add:
- M-DCT
- Navi (I-drive stuuf)
- Premium audio, parktronics, etc.
What the power to weight ratio will be with the equiped car then?
Thanks.
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      04-09-2008, 04:31 AM   #2
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M-DCT adds about 45kg.

Nav (purely a guess!) could be 5kg???

Audio maybe another 5kg????

Difference in power to weight 250bhp/ton for a base Coupe Vs 242bhp/ton for a car with the M-DCT etc...... however the M-DCT car will still be quicker due to its better gearing and super quick shifts.
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      04-09-2008, 07:07 AM   #3
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I heard 45 lbs for DCT not 45 KG for DCT.
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      04-09-2008, 08:17 AM   #4
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Quote:
Originally Posted by rai View Post
I heard 45 lbs for DCT not 45 KG for DCT.
you heard correct
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      04-09-2008, 08:23 AM   #5
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Quote:
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you heard correct
I stand corrected sorry its only 20kg for DCT not 45!!!
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      04-09-2008, 09:39 AM   #6
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I stand corrected sorry its only 20kg for DCT not 45!!!
Wow, that is nothing!! And NAV would have te be less than 5 kg as well IMO.
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      04-09-2008, 11:52 AM   #7
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Honestly the only real option that will add any perceptible difference in weight are the 18's vs 19's. The 18's save about 4-6lbs per corner in unsprung weight. That is getting close to 100lbs. If you think about it thats like riding with a trim/short girl in the passenger seat.

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      04-09-2008, 12:23 PM   #8
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the sunroof does add some weight. I dislike sunroofs not just for the weight but the CF < steel < sunroof and the weight is at the top of the car which is almost the worst place to have it.

I think the steel roof is about 10 lbs more than the CF roof and the sunroof adds another 10 lbs. So in other words a sunroof on a coupe is probably 20 lbs more than the CF standard roof.

I forget the exact weight but I think it's like 20 lbs.

Likely the premium stereo weighs a fair amount with speakers and extra amps those things are not nothing.

Last edited by rai; 04-09-2008 at 12:39 PM.
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      04-09-2008, 12:28 PM   #9
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Unless you are going to be doing extensive timed runs on a track, you won't notice a difference in real life.

As far as being faster than a heavier M3 not only depends on the weight of the car, but the amount of fuel, driver skills etc. In my opinion, you should get the option you want unless you are going to build a track car and plan on gutting it out.
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      04-09-2008, 01:39 PM   #10
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Quote:
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Unless you are going to be doing extensive timed runs on a track, you won't notice a difference in real life.

As far as being faster than a heavier M3 not only depends on the weight of the car, but the amount of fuel, driver skills etc. In my opinion, you should get the option you want unless you are going to build a track car and plan on gutting it out.
I tend to agree, all the options don't look to be more than 100 lbs one way or the other.

Except the Vert option which is 400 lbs (I think) I have not driven but likely that's very heavy feeling compared to the least M3.
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      04-09-2008, 01:51 PM   #11
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Quote:
Originally Posted by JEllis View Post
Honestly the only real option that will add any perceptible difference in weight are the 18's vs 19's. The 18's save about 4-6lbs per corner in unsprung weight. That is getting close to 100lbs. If you think about it thats like riding with a trim/short girl in the passenger seat.

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      04-09-2008, 08:47 PM   #12
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Actually, GregW weighed the stock 19s with tires and is estimating 23 lbs front and 26.5 lbs rear (give or take a pound after subtracting tire weight). We won't know for sure until someone weighs the stock 18s, but the 19s may actually be the stock lightweight option for this car.
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      04-09-2008, 09:32 PM   #13
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Quote:
Originally Posted by Ronin13 View Post
Actually, GregW weighed the stock 19s with tires and is estimating 23 lbs front and 26.5 lbs rear (give or take a pound after subtracting tire weight). We won't know for sure until someone weighs the stock 18s, but the 19s may actually be the stock lightweight option for this car.
That sounds encouraging. Still, the 18s have their main mass (the wheel) .5" closer to the center so even if they weigh the same there might be a slight advantage. At any rate, I bet the difference in weight between the two sizes is less than most believe at this point. I'm getting the 19s, BTW. I looked for tire weights (18s vs 19s) and couldn't find anything.
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      04-09-2008, 09:45 PM   #14
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Quote:
Originally Posted by RandyB View Post
That sounds encouraging. Still, the 18s have their main mass (the wheel) .5" closer to the center so even if they weigh the same there might be a slight advantage. At any rate, I bet the difference in weight between the two sizes is less than most believe at this point. I'm getting the 19s, BTW. I looked for tire weights (18s vs 19s) and couldn't find anything.
www.tirerack.com
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      04-09-2008, 10:27 PM   #15
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Thanks. According to the weights listed on The Tire Rack, the 19" rears are 1-2 lbs lighter than the 18" and the fronts are 0-1 lb lighter than the 18s. They have several listed of each size so I'm not sure which weight to use, thus the range. I bet the combined tire/wheel weight between the 18s and 19s will be nearly negligible.
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      04-10-2008, 01:18 AM   #16
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Quote:
Originally Posted by JEllis View Post
Honestly the only real option that will add any perceptible difference in weight are the 18's vs 19's. The 18's save about 4-6lbs per corner in unsprung weight. That is getting close to 100lbs. If you think about it thats like riding with a trim/short girl in the passenger seat.

Jason

this is unfounded. the 19's wiegh less than we thought thanks to greg for wieghing them.

moonroof 56#
DCT 45 #
other misc. options 5#

total 106 #.

Last edited by sayemthree; 04-11-2008 at 02:25 AM.
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      04-10-2008, 11:33 PM   #17
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I read that the Steel roof weighs 12 lbs more than the CF roof, and getting the sunroof in the Coupe rather than CF adds 42 lbs. So in other words, getting the sunroof in the sedan should add about 30 lbs over just a plain steel roof.

To me this is real weight that is in the wrong location. Then factor in $1050 savings and I will be leaving the sunroof out.
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      04-11-2008, 02:26 AM   #18
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carbon fiber roof FTW!!!!!!!!!
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      04-11-2008, 03:02 AM   #19
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just weighting the tires on a scale will not give you the true answer.
Moment of inertia needs to be calculated for the wheel + tire.

When accelerating the available torque at the wheels will be fighting a greater resistance to angular rotation acceleration if the moment of inertia is higher and that will result in less traction on the road for acceleration.

The moment of inertia is proportional to the distance of the mass to the centre of rotation squared. So 18 to 19 inch can still make a 11% increase even if the tires weight the same.

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      04-11-2008, 06:07 AM   #20
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Quote:
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The moment of inertia is proportional to the distance of the mass to the centre of rotation squared. So 18 to 19 inch can still make a 11% increase even if the tires weight the same.

That is correct and I touched on it in my post. I still bet it is going to be close between the two stock sizes because the 19" tires look to be a pound or two lighter than the 18s. Maybe that will help offset some of what the rim difference is because the tires are even further from the center.
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