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brkf
05-19-2008, 03:39 PM
How is it that BMW's 325 and 330 e46s and 328 and 335 e90s have nearly 50:50 weight distribution?

The current e9x 328 weighs 3340 while the 335 weighs 3594.

The 328 is 50.5: 49.5 for weigh distribution while the 335i 51.5:48.5. 1% of 3300 lbs is only 33 lbs. So how is it that BMW's 3.0 TT, which weighs more than the 3.0 only upsets the balance by ~35 lbs, yet the car gains 250 lbs?

Is BMW adding weight to the back of their cars in an effort to achieve close to 50:50? Feature content arguments are questionable as only the power seats seem to add weight and if anything that weight is also concentrated in the front half of the car.

synenergy52
05-20-2008, 09:04 AM
Maybe there's other aspects of the 335i which add to the weight in the rear. Dual exhausts, heavier/beefier rear end (driveshaft/axles, etc)

brkf
05-20-2008, 10:55 AM
Maybe there's other aspects of the 335i which add to the weight in the rear. Dual exhausts, heavier/beefier rear end (driveshaft/axles, etc)

Perhaps. Find it odd we've not seen more responses. Isn't there one BMW engineer or uber-bimmer geek that can answer how this happens?

AzNMpower32
05-20-2008, 03:28 PM
I've always wondered more about how BMW keeps their SAVs 50/50. I mean, I know the battery and spare tire is one thing, but geez. Perhaps the fact the wheels are pushed out to the far corners and there is little hangover has something to do with it.

Jspeed
05-21-2008, 10:31 PM
The current e9x 328 weighs 3340 while the 335 weighs 3594.

The 328 is 50.5: 49.5 for weigh distribution while the 335i 51.5:48.5. 1% of 3300 lbs is only 33 lbs. So how is it that BMW's 3.0 TT, which weighs more than the 3.0 only upsets the balance by ~35 lbs, yet the car gains 250 lbs?

Let's try some math...

According to the numbers given, the 328 has 1687 lb over the front axle and 1653 lb over the rear axle. The corresponding figures are 1851 and 1743 for the 335. The 335 is 164 lb heavier at the front and 90 lb heavier at the rear.

Now let's isolate the weight difference of the engines. The N54 (412 lb) is 57 lb heavier than the N52 (355 lb), so as far as the rest of the car is concerned, the 335 is 107 lb heavier at the front and 90 lb heavier at the rear.

This sounds quite reasonable.

plien69
05-22-2008, 09:09 AM
I've always thought that BMW design philosophy included pushing the front wheels as far forward as possible, in order to get as much engine as possible behind the front axle/strut towers.

If you look at a lot of other cars and try to visualize where the engine is, many have the engine in front of the front axles. Not only does this increase weight in front by itself, it also -- by way of levering forces -- lightens the weight on the rear axle.

In addition, RWD design pushes more weight rearward as well, with the driveshaft and rear axle assembly.

brkf
05-25-2008, 12:49 AM
Let's try some math...

According to the numbers given, the 328 has 1687 lb over the front axle and 1653 lb over the rear axle. The corresponding figures are 1851 and 1743 for the 335. The 335 is 164 lb heavier at the front and 90 lb heavier at the rear.

Now let's isolate the weight difference of the engines. The N54 (412 lb) is 57 lb heavier than the N52 (355 lb), so as far as the rest of the car is concerned, the 335 is 107 lb heavier at the front and 90 lb heavier at the rear.

This sounds quite reasonable.


What's the extra weight at the back?

Pinecone
05-27-2008, 07:00 AM
It is more weight overall.

But the answer to the original question is yes, BMW has been known to add weight to the rear of the car. The M Roadster/Coupe (Z3 version) has a pair of "cowl shake elimantors" under the rear bumper cover. These are weights that help get the near 50/50 wieght distribution.

And BTW 50/50 weight distirbution is more of a marketing tool that anything real. Most race cars aren't 50/50 by design.

mapezzul
05-27-2008, 07:10 AM
It is more weight overall.

But the answer to the original question is yes, BMW has been known to add weight to the rear of the car. The M Roadster/Coupe (Z3 version) has a pair of "cowl shake elimantors" under the rear bumper cover. These are weights that help get the near 50/50 wieght distribution.

And BTW 50/50 weight distirbution is more of a marketing tool that anything real. Most race cars aren't 50/50 by design.

The 135i has weight added as well...

mapezzul
05-27-2008, 07:12 AM
What's the extra weight at the back?

Wheels, tires, brakes,and exhaust.

kyfdx
05-27-2008, 09:59 AM
Perhaps. Find it odd we've not seen more responses. Isn't there one BMW engineer or uber-bimmer geek that can answer how this happens?

Not an engineer or an uber-geek.. but, in the past, BMW has used lighter weight suspension materials upfront (aluminum), and regular steel in the back.. Even though aluminum all the way around would be lighter (and more expensive!), they do that to keep the weight balance as close to 50/50 as possible..

I'd think they could probably do the same thing with body panels (composite fenders upfront, aluminum hoods, etc)..

I don't have any specifics on the current models, though..