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      08-29-2010, 04:24 PM   #89
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shereef, i'm guessing ur interior refinish was done not with the aim to reduce weight, but as a matter of increased space, luxury and sound reproduction. it's a top-notch, cleanly done job and i wouldn't be concerned at all with lost stiffness/rigidity unless u're a closet track monster at heart!
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      08-29-2010, 04:56 PM   #90
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Quote:
Originally Posted by Shereef_Osman View Post
Nothing rigid about the parts that were removed. We would have removed everything but I didn't want to have to deal with a harness everyday. Thanks for the smart ass comment non the less.
apparently a lot of people here agree with my comment
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      08-30-2010, 09:13 AM   #91
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Hmmm. If we accept that removel of the piece doesn't affect rigidity of the car while driving, and we believe that BMW would have used some other material if the panel was not structural, it begs the question of what the panel is intended to do!

Most intriguing!

In the interest of discussing ( and not to piss off anyone!) do folks think that it may have been intended to prevent the cabin from splaying apart in a rear-end collision? If its not for rigidity of the car while driving, tha's all I can think of.

Cheers!
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      08-30-2010, 09:46 AM   #92
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Quote:
Originally Posted by Shereef_Osman View Post
Here you go!
Woah, man, first off, welcome to the forum. Second, if you haven't already, you need to post up some kind of documentary on what you've done with your car. Major work there! Definitely worth a run down of how it went, weight loss or not. That back area look great, very well finished and professional looking. How did you tie the console in - that would be my biggest question. Excellent work, all structural and weight talk aside.
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The thought that the bulkhead was left over from the roadster is an intersting one, I'm not sure it's a legitimate one. I'd like to hear from a BMW engineer on that one. On one hand, I can see the company leaving it for the reason of not having to deal with removal and an entirely different interior design, bulk-head forward (IIRC, the coupe and roadster interiors from the bulk head forward are very similar, no?). On the other hand, I thought the coupe was structurally a different design than the roadster (can't claim to know the details though....) so if it's a different design, why wouldn't they remove the bulkhead if they could?

All I know is that on the Z4MC race car that our friend had, they left the bulkhead and built the cage integral with it. I don't know why they didn't do it like in the white coupe above - seems like that might have been easier - however, we did have to deal with the oil sump being back there. The rear compartment on his Z4MC was a bit more open and accessible. And.....we know that with out all the extreme cross bracing that the cage held up in a total loss wreck...which leads me to believe that the builder of the race car believed that the bulkhead had a definite purpose in the structure of the car with a cage and in a race application.

All that said, sure would be a different animal with out the bulkhead - sort of Corvette-esque being able to reach into the rear compartment from a front seat.
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      08-30-2010, 10:04 PM   #93
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Quote:
Originally Posted by Finnegan View Post
That's one hard-core entertainment set-up! It sounds like the main structural component--the bottom of the bulkhead--was left intact. And you did your homework.

I'd have more concerns about the mod if this were the roadie however. The coupe has some inherent structural advantages, so if there is an "issue" it's probably minimal.

Like I said before, I really like the look and enhancements.

It does sound like, if you wanted to cut weight, this type of mod could help. And if you're uber worried about torsional stiffness, some custom "scaffolding" could probably address that and stiff provide net weight savings.
I agree, definitely wouldn't touch it in a roadster. Thanks for the compliments!

If you really wanted to cut weight, this could easily lead to at least 100 pounds if done properly with a harness and roll bars etc.
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      08-30-2010, 10:09 PM   #94
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Quote:
Originally Posted by r4gs View Post
shereef, i'm guessing ur interior refinish was done not with the aim to reduce weight, but as a matter of increased space, luxury and sound reproduction. it's a top-notch, cleanly done job and i wouldn't be concerned at all with lost stiffness/rigidity unless u're a closet track monster at heart!
I am a track junkie, lol, my poor M has been to the track more than I would have liked, probably like 20 times in the last year and a half. Until the middle of last year I had an E30 that I used for my track car, then I decided to build it up over the winter and obviously it wasn't finished in time, so the M has been my replacement. Last week I actually checked the mileage and I did 196km at Shannonville, something like 50 laps! Lol If one day the M turns into my track car, I would defnitely remove the whole bulkhead and put in some roll bars for safety / stiffness.
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      08-30-2010, 10:16 PM   #95
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Quote:
Originally Posted by onebluemcm View Post
Woah, man, first off, welcome to the forum. Second, if you haven't already, you need to post up some kind of documentary on what you've done with your car. Major work there! Definitely worth a run down of how it went, weight loss or not. That back area look great, very well finished and professional looking. How did you tie the console in - that would be my biggest question. Excellent work, all structural and weight talk aside.
__________________________________
The thought that the bulkhead was left over from the roadster is an intersting one, I'm not sure it's a legitimate one. I'd like to hear from a BMW engineer on that one. On one hand, I can see the company leaving it for the reason of not having to deal with removal and an entirely different interior design, bulk-head forward (IIRC, the coupe and roadster interiors from the bulk head forward are very similar, no?). On the other hand, I thought the coupe was structurally a different design than the roadster (can't claim to know the details though....) so if it's a different design, why wouldn't they remove the bulkhead if they could?

All I know is that on the Z4MC race car that our friend had, they left the bulkhead and built the cage integral with it. I don't know why they didn't do it like in the white coupe above - seems like that might have been easier - however, we did have to deal with the oil sump being back there. The rear compartment on his Z4MC was a bit more open and accessible. And.....we know that with out all the extreme cross bracing that the cage held up in a total loss wreck...which leads me to believe that the builder of the race car believed that the bulkhead had a definite purpose in the structure of the car with a cage and in a race application.

All that said, sure would be a different animal with out the bulkhead - sort of Corvette-esque being able to reach into the rear compartment from a front seat.
Thanks! This forum has been a great wealth of information, lots of great people on here.

I have been meaning to keep a log of all my modifications but never really got round to it. I will have to get something going though. I'll try to take some more pictures of the car so at least you can get some idea of how things were done in terms of the console area.

As I said I checked with two shops and they both said the same thing, so I believed them. But in truth, is it weaker? Possibly. It is noticeably weaker? Did it affect the performance? From what I have noticed, not in the slightest!
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      09-06-2010, 01:22 AM   #96
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Sorry, but I am not sure this is accurate, so I'll just post it up. iirc the S2000 is heavier, infact I believe it to be a different GVW measurement being theoretical, not actually true. Something about assuming two occupants, a full tank of gas AND calculated weight based on cargo space. I took my 7'er to a truck scale and it was substantially less than what other people, and wiki, said the GVW would be. The plate on my door said 4700lbs, but I'll tell you what, it was a lot less than that but I am not exactly trusting scales made for vehiles over 14,000lbs of GVW.

A friend of mine that is studying to be a BMW tech out at UTI looked at his E39 M5 and I think did the same thing, he was taught the same thing, added weight based on those factors, so a trunk'd car may not be the same as a hatchback for that theoretical load.

Has anyone *actually* measured or is this all spitballing trusting plates, manuals and popular opinion?
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      09-06-2010, 12:53 PM   #97
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Here's some weight savings that I've done to mine…

Cobra Suzuka seats (including custom floor mounts) = -70 lbs
Morr VS8's : 8 lbs a wheel lighter ( i believe ) = -48 lbs
Braille 15lb battery = -30 lbs
SS Powerloop mufflers = -20 lbs
Removed secondary cats / replaced with stainless tubing = -12 lbs

So just this stuff equals +-180 lbs less than stock. You really notice a big difference in acceleration, especially on the freeway. I also keep my windshield washer tank empty ( living in so cal you never need it anyway / I never drive it in the rain ) and I also for the most part only fill my gas tank up half way. I still don't understand why I do that, but I do… hahahaha
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      09-07-2010, 12:16 PM   #98
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Your MORR tire weight savings calculation is a little off at -48lbs, if indeed each rim is 8 lbs lighter. 4 x 8lbs = 32 lbs lighter.

You may be counting tires as well for that total -48lbs lighter total, though, but right now it doesn't add up.

Looks like you've saved a lot of weight w/o stripping the interior. Good job.
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      09-07-2010, 04:31 PM   #99
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Quote:
Originally Posted by esqu1re View Post
Your MORR tire weight savings calculation is a little off at -48lbs, if indeed each rim is 8 lbs lighter. 4 x 8lbs = 32 lbs lighter.

You may be counting tires as well for that total -48lbs lighter total, though, but right now it doesn't add up.

Looks like you've saved a lot of weight w/o stripping the interior. Good job.
Brainfart... my bad. I actually have the 2317 battery as well ( 17 lbs ) stock battery is 49 tho... so still a big savings.
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      09-07-2010, 07:01 PM   #100
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Pee before driving: -2lbs
Haircut: -1lbs
Donate kidney: -2lbs
Drive naked: -2lbs
Date anorexic midget: -40lbs
Fasting: -10lbs (your milage may vary)

I feel light headed, but I'm fast!


But in all seriousness, that is some great weight savings there man! Being in SoCal, you could of course pull the A/C and heater core. Out of all that, I would probably have kept the battery for the weight in the rear, I imagine the rear getting a bit light in sharp cornering.
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      11-29-2010, 10:12 PM   #101
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Excellent thread. Does anyone know what a typical variance is between the advertised weight and the actual delivery weight?

My car should weigh 2,865 lbs, but is coming in at 2,884 lbs. That is only 19 lbs difference, and could be scale error, a heavier than expected car, or both. I was just wondering what a normal difference might be between delivery and advertised-- especially since my measurement was on a nearly empty tank and the consensus here is that BMW does "wet" weights.

The 2004 Z4 3.0i is supposed to weigh 3,009 lbs. Mine came with the sport/premium packages.

I weighed mine with a nearly empty tank and after losing weight from the following changes:

Battery -32
Wheels -41
Springs -6
Seats - 70
Camber plates +5

Theoretical = 2,865
Actual = 2,884

Thanks
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      11-30-2010, 11:48 AM   #102
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Quote:
Originally Posted by shift@red View Post
Most manuf. besides Ferrari claim wet weight.
Porsche weights are dry.
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      12-23-2010, 01:47 AM   #103
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After exhaust mufflers, coilovers, wheels, driver bucket seat, and taking out some of the tools above the battery, my car weighed in @ 3180 lbs. with 1/4 tank of gas.
I also did a full tank weighing with the above setup, and it came in @ 3260 lbs.

Since then, I've gotten a different set of wheels/tires, and have swapped out the stock headers. I will report back with my weight findings, since I have a weigh station nearby

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      02-03-2011, 09:03 PM   #104
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With full tank of gas and all the mods listed in my signature (excluding APR splitter), my car weighed in @ 3220-3240 (scale is + 20 lbs.)
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      02-03-2011, 11:55 PM   #105
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hmm, I thought the seats would make a bigger difference
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      02-04-2011, 12:38 AM   #106
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Quote:
Originally Posted by Roffle Waffle View Post
hmm, I thought the seats would make a bigger difference
I only swapped out the driver's seat. Left the passenger seat alone, since I didn't want to deal with the airbag stuff. Plus, I only had one bucket seat available from my MR2
The OEM heated and powered seat weighs in at almost 60 lbs.
And typical bucket seats weigh in at around 15 lbs. excluding mounting hardware, etc. so a full seat with hardware is probably around 20 lbs. total give or take. That means a weight savings per seat of about 40 lbs. or so.
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      02-04-2011, 01:05 AM   #107
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if you swap the battery with the new Porsche GT3 9 pound lithium battery (2.5k) you save like another 45 pounds right there....im just saying
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      02-04-2011, 07:39 AM   #108
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LoL, has anyone done this on a Z4M yet? Link to the batt for purchase? Are specs the same? I'd be down to lose some weight =P
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      02-04-2011, 09:43 AM   #109
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Argh. With a full tank of gas, yours is still in the 3200's. Mine is pretty much stock, and it must weigh 3300+ with a tank of gas. Sad face.
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      02-04-2011, 10:00 AM   #110
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Quote:
Originally Posted by Z4-Villalona View Post
if you swap the battery with the new Porsche GT3 9 pound lithium battery (2.5k) you save like another 45 pounds right there....im just saying
interesting... didnt realize the standard bat weighed that much. Any cons to this?
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