Z4M - carrying a few too many lbs?

Trav · Post by **Trav** » Tue Nov 27, 2018 8:52 am

Also look on fastestlaps.com at the torque to weight ratio. You need to look at the value of your weight losses against adding more Nm of grunt. Remove a bit of weight and add a bit of grunt. Cost and discomfort goes up a lot the more of each you do. Look where you get best value.

wspohn · Post by **wspohn** » Tue Nov 27, 2018 6:04 pm

Very hard to seriously lighten a modern car while retaining functionality.

One of my old English race cars was 1700 lbs and the other was just under 2000. Today with all the added collision measures (side intrusion beams in doors etc.) mod cons (things like motorized seats) and such, the only ones that can be considered to be relatively light weight are Lotus and the Miata. Most sports cars are up around the 3,000 mark, and the added weight takes a toll, although the extra 150 lbs or so over a Cayman or Solstice isn't going to kill a Z4. What is does is make the modern sports cars less agile and heavier feeling in terms of handling.

If you have ever driven a Lotus Europa (1600 lbs) in anger will be able to appreciate the difference. Lightening a street car like the Z4 is usually a thankless job - limited results and often reduced resale value. Building a dual purpose street/track car would be the only exception to that.

Vanne · Post by **Vanne** » Mon Dec 03, 2018 2:03 pm

doing some of this atm. stripped the rear, 11 pound braile batt and holder, and removing all 3 modules that are on the rear bulk head. removing the air pump and radio/nav/speakers. plus the barage of sensor mounts that are mounted on the rear wheel wells.

looking at changing door cards, but that will be Alcantara project in itself.

MrPT · Post by **MrPT** » Tue Dec 04, 2018 12:24 am

Vanne wrote: ↑Mon Dec 03, 2018 2:03 pm doing some of this atm. stripped the rear, 11 pound braile batt and holder, and removing all 3 modules that are on the rear bulk head. removing the air pump and radio/nav/speakers. plus the barage of sensor mounts that are mounted on the rear wheel wells.

looking at changing door cards, but that will be Alcantara project in itself.

Do you know how much the CF roof saved you in the end? I know it’s not a huge amount but it’s the highest part of the car and I don’t think the price is too silly for a moderate saving.

Vanne · Post by **Vanne** » Tue Dec 04, 2018 1:45 am

savings were 15.3 kgs. carbon roof was 1.9kgs before clear coat, and the oem e86 roof weighs about 17.3 kilos.

There is a hell of a lotta weight in the standard oem battery and tray.. 25kgs savings (thats a few big macs)

there is another easy 7kgs in the rear sub woofers alone.

nav and Audio:
04.8 lbs-Harness
01.0 lbs-misc brackets
04.2 lbs-2 Kick panel Speakers
14.2 lbs-2 Rear subwoofers
00.2 lbs-GPS antenna
09.0 lbs-Amps/amp brackets
03.4 lbs-4 mid range speakers
00.2 lbs-2 tweeters
03.6 lbs-GPS/DVD drive
02.4 lbs-Pop-up display
02.6 lbs-Head unit

MrPT · Post by **MrPT** » Tue Dec 04, 2018 9:32 am

Vanne wrote: ↑Tue Dec 04, 2018 1:45 am savings were 15.3 kgs. carbon roof was 1.9kgs before clear coat, and the oem e86 roof weighs about 17.3 kilos. There is a hell of a lotta weight in the standard oem battery and tray.. 25kgs savings (thats a few big macs)

Decent savings. I'd be wary of the capacity of a lightweight battery, but I've seen people install a couple of Brailles in parallel across the rear bulkhead, which is a really neat installation and probably gives you a bit of safety margin for trips abroad etc.

Vanne · Post by **Vanne** » Tue Dec 04, 2018 1:30 pm

i also have the tv/media system box on the bulkhead, that puppy is at least 3 kgs.

I have the braille 11lbs batt, its big enough. But it does need to live on a tender, or hooked up to another batt while in storage.. (should last 2 weeks without anything hooked up to it)

So shouldn't be too much of a drama. Its not a daily driver for me.

TomK · Post by **TomK** » Tue Dec 04, 2018 2:28 pm

Vanne wrote: ↑Tue Dec 04, 2018 1:45 am the oem e86 roof weighs about 17.3 kilos.

you sure about that? 17kg for a small roof panel seems quite a lot (a lot more than a wing for instance) and everyone else I can find on the internet who has done this says they weigh about 7 and the saving is around 5kg max?
If it really is that much then great, I'll get it done!

Vanne · Post by **Vanne** » Tue Dec 04, 2018 3:41 pm

quoting numbers from another weight thread, i asked that same question, ill let you know what the guys say.. i could ofcourse pull out my roof and chuck it on the scales, but id rather not make a huge mess in my parts room.

TomK · Post by **TomK** » Tue Dec 04, 2018 4:58 pm

That guy Z4MGT4 has just ordered a BMW one from the other thread , I'll drop him a pm and see if he can get the package weight..

mmm-five · Post by **mmm-five** » Tue Dec 04, 2018 5:00 pm

bmwfans.info claims it weighs 17.5lbs, or 7kg.

Argenta · Post by **Argenta** » Tue Dec 04, 2018 5:04 pm

That small piece of aluminium being the roof cannot possibly weigh 17kg's...

TomK · Post by **TomK** » Tue Dec 04, 2018 5:08 pm

Pretty sure it's steel, but all the same, I find it unlikely to weigh the same as a battery!

Beedub · Post by **Beedub** » Tue Dec 04, 2018 5:27 pm

i recently went to a body shop to do a correction on a loose roof panel from an rs3... which is considerably bigger... the arse holes left me to lug it around it was awkward but if it weighed more than 10kg ill eat my shoe. No way the z4 roof is 17kg.. just no way at all.

Argenta · Post by **Argenta** » Tue Dec 04, 2018 9:27 pm

TomK wrote: ↑Tue Dec 04, 2018 5:08 pm Pretty sure it's steel, but all the same, I find it unlikely to weigh the same as a battery!

No, it’s aluminium as is the bonnet.

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