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      09-17-2014, 09:57 AM   #1
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magnetic vs non-magnetic panels?

Of course the front and rear bumpers are plastic, but I noticed that the hood and side panel (where the side turn indicators are), while metallic, are not magnetic. The other body panels are metallic, save for 1 part of the roof. Is there a reason for this...?
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      09-17-2014, 12:37 PM   #2
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Sure is - aluminum. Aluminum is not magnetic, and saves weight. The hood and roof I was aware of, but I wasn't aware of the side panel(s) you're referring to being aluminum (aluminium for all our UK Zed owners). Anyone know if that's indeed true?
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      09-17-2014, 01:46 PM   #3
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It's true that it's aluminum for the side panel where the blinkers are: the hood, I think the trunk and also 1 part of the roof are also. Of course, the bumpers are plastic.
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      09-17-2014, 03:42 PM   #4
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All Looo minnn eeeuuummmm
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      09-17-2014, 05:08 PM   #5
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All Looo minnn eeeuuummmm
A fine Jony Ive impression sir.
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      09-17-2014, 05:54 PM   #6
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I did not know the Z'ed body panels were Aluminum. I thought the top was a fiberglass composite?

Am I incorrect ?
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      09-18-2014, 08:45 AM   #7
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Originally Posted by BMWZ4RIDER View Post
I did not know the Z'ed body panels were Aluminum. I thought the top was a fiberglass composite?

Am I incorrect ?
The top is not metal for the most part I do think it is a composite material. However i think the bonnet and some panels are Al
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      09-18-2014, 11:34 AM   #8
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Quote:
Originally Posted by rking117 View Post
The top is not metal for the most part I do think it is a composite material. However i think the bonnet and some panels are Al
There aren't any composite body panels on our Z4s. Unless of course you've replaced what the factory put on there with some aftermarket bits .

The hood and trunk lid are aluminum, and this is also a carry over from the E85 - they were aluminum on those as well. The folding hard top is also aluminum, and thin aluminum at that.

What I wasn't aware of (and seems to be speculated/confirmed about in this thread) is that the side panels containing the turn indicator and Roundel are also aluminum.
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      09-18-2014, 11:59 AM   #9
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Quote:
Originally Posted by tranquility View Post
It's true that it's aluminum for the side panel where the blinkers are: the hood, I think the trunk and also 1 part of the roof are also. Of course, the bumpers are plastic.
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Originally Posted by mbetoni View Post
The hood and trunk lid are aluminum, and this is also a carry over from the E85 - they were aluminum on those as well. The folding hard top is also aluminum, and thin aluminum at that.

What I wasn't aware of (and seems to be speculated/confirmed about in this thread) is that the side panels containing the turn indicator and Roundel are also aluminum.

Actually, I should probably clarify that those parts are not metallic, that's all I know and should be my only claim. As to the actual material/composition, e.g. aluminum or otherwise, not sure.
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      09-18-2014, 10:43 PM   #10
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Quote:
Originally Posted by tranquility View Post
Actually, I should probably clarify that those parts are not metallic, that's all I know and should be my only claim. As to the actual material/composition, e.g. aluminum or otherwise, not sure.
The fender (side panel where the blinker is located) is aluminum. I had to order a new fender (OEM from BMW), and I forgot where I saw it (it was either the catalog or on the description of the item) but it was listed as "Al" for aluminum.
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      09-19-2014, 01:37 AM   #11
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If there is so much Al.. why is the car still 3500lbs
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      09-19-2014, 03:44 AM   #12
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If there is so much Al.. why is the car still 3500lbs
Yes, why so heavy? Why doesn't it have a more powerful engine or more enhanced for the price we paid? Why doesn't it have LSD? Why does it have RFT? Why is the leather so crappy? Why didn't they get the paddle setup right the 1st time (i.e. -/+ is best!)? Why didn't they get the roof mech right the 1st time? Why didn't the lousy fuel injectors get extended warr?

Ok, rant over.
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      09-19-2014, 02:18 PM   #13
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Quote:
Originally Posted by nicknaz View Post
If there is so much Al.. why is the car still 3500lbs
I might have been sitting in it when it ran across the scales. hahaha
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      09-19-2014, 06:38 PM   #14
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Quote:
Originally Posted by tranquility View Post
Yes, why so heavy? Why doesn't it have a more powerful engine or more enhanced for the price we paid? Why doesn't it have LSD? Why does it have RFT? Why is the leather so crappy? Why didn't they get the paddle setup right the 1st time (i.e. -/+ is best!)? Why didn't they get the roof mech right the 1st time? Why didn't the lousy fuel injectors get extended warr?

Ok, rant over.
Sort of off-topic, but I'm not even convinced it is done right now. I was speaking with the manager of a Certified BMW Repair Center and he used to have an E93. Said the roofs on the BMWs are pretty good, but issues will really start to show up after 5-6 years. I believe him - only a year in and my roof hasn't stopped rattling despite many dealership visits. Even went as far as to say that Mercedes has the best (hardtop) roof and is rock solid. Test drove an SLK before the Z4, he's not wrong. So quiet you can hear a pin drop. And then he challenged me: How much do you think a replacement roof is?




















$20,000
Really makes you reconsider leasing as opposed to purchase as a keeper.
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      09-19-2014, 06:51 PM   #15
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Quote:
Originally Posted by tranquility View Post
Yes, why so heavy? Why doesn't it have a more powerful engine or more enhanced for the price we paid? Why doesn't it have LSD? Why does it have RFT? Why is the leather so crappy? Why didn't they get the paddle setup right the 1st time (i.e. -/+ is best!)? Why didn't they get the roof mech right the 1st time? Why didn't the lousy fuel injectors get extended warr?

Ok, rant over.
I know you were joking, but I agree completely.. especially the weight/power/LSD.. I will report back on the replacement in a few months
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      09-19-2014, 07:21 PM   #16
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Nick, have you decided if it's going to be the stingray yet?

Too bad the C63 won't be out by the time your lease is up, or I think it would be a serious contender!
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      09-19-2014, 07:32 PM   #17
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Quote:
Originally Posted by CedarZ4 View Post
Nick, have you decided ...
Cedar, no decisions yet other than I would like the car to trap 120mph bone stock (incl tires) from the factory.

Definitely lots of non-magnetic / Al on the contender cars though.. just like E89

see that.... back on topic
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      09-20-2014, 11:36 AM   #18
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Quote:
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I know you were joking, but I agree completely.. especially the weight/power/LSD.. I will report back on the replacement in a few months
Sadly enough, I wasn't and feel that they were valid rants. Still a great car, but wished that BMW gave us more 'value' for the $$$ we spent on them.
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      09-20-2014, 01:08 PM   #19
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Quote:
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If there is so much Al.. why is the car still 3500lbs
Because it's a modern roadster, built for today's market and focusing on tomorrow's sensibilities.

Open-topped cars were traditionally wobbly affairs, so compromised for handling and ride, not to mention safety. That won't fly now, so the structure beneath those alloy panels is built up to a strength rating, instead of down to a weight. Make a rigid car first, then add lightness. Modern safety and comfort equipment, multiple airbags, automatic climate control, iDrive; all add weight, but just try selling a car without them...

Instead, the weight saving is strategic; bonnet/hood, trunk/bootlid, front wings, these overlap the ends of the wheelbase and lowering their weight concentrates more weight inside the wheelbase, improving handling. The plastic bumpers/fenders further this philosophy, whilst being cheaper to replace after a bump. The light alloy roof lowers the centre of gravity when raised and demands smaller, lighter motors to open and close it; ditto the boot/trunklid which opens to stow the roof. The doors are all-steel aren't they? This greatly improves rigidity in a crash as steel is less flexible than aluminium/aluminum; with the doors open it's just the floorpan that has to take all the punishment. Steel is also better for side-impact protection, not to mention feeling more weighty and sounding more solid when you close the doors; perceived quality is very important in the showroom. Does the suspension use any alloy components? Do the brakes have separate alloy hats/bells? These measures would help reduce unsprung weight which is very useful if kept to a minimum.

At the end of the day, the car can't be all-that light as an all alloy construction, or composites like carbon fibre, would simply make it too expensive for its market segment. Being open-topped requires the roll-over hoops (high strength steel?) and reinforced windscreen frame and glass (triple laminated?). These add significant weight. The Run Flats are due to packaging; the small rear end has to contain BMW's sophisticated rear suspension, the (small) fuel tank, the entire gubbins to stow the roof, usable boot/trunk space, the driveshaft and diff,, the enclosures for the subwoofers behind the seats if fitted, enough room to recline the seats themselves for comfort... there's nowhere for a spare wheel, even a space saver. The car I'm looking at has normal tyres, thankfully; runflats would be murder on our roads.

The lack of LSD is quite vexing. The obvious reason is BMW don't want the car competing with their more elite M Power machinery, but I like to think it's to make the car more of a GT; LSDs are quite twitchy I've heard.
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      09-20-2014, 02:25 PM   #20
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^Cmon, the Z4's wt is way too much, nothing can justify that; they're just being lazy and cost-cutting, I'm sure that they could've made it a LOT lighter.
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      09-20-2014, 03:33 PM   #21
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Again, it comes down not just to cost but not wanting to make it "too good" or the more expensive models lose their allure.

If there were an M version of the E89, you'd probably see a lot of carbon panels to reduce weight, starting with the entire roof shell.
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      09-21-2014, 03:15 AM   #22
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Quote:
Originally Posted by Visionist View Post
Again, it comes down not just to cost but not wanting to make it "too good" or the more expensive models lose their allure.

If there were an M version of the E89, you'd probably see a lot of carbon panels to reduce weight, starting with the entire roof shell.
Boxster costs the same and is 500lb lighter. I guess BMW was trying to make a discount SL and not a boxster competitor.
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