EXXEL Distributions
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   BMW M3 and BMW M4 Forum > BMW F80 M3 / F82 M4 Forum > BMW M3 (F80) and BMW M4 (F82) General Forum

Post Reply
 
Thread Tools Search this Thread
      03-24-2014, 07:15 PM   #67
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

Quote:
Originally Posted by mkoesel View Post
Good to see the E90 335i still in service there, doc. Over 100k miles? Nice to see you here on the F8x forum.

I'm sure you're right about aftermarket racks for the CF roof. I'd still prefer the OEM rails. If the CF roof does rule out the use of OEM brackets, it sure would be nice to know why.
Stress fractures and liability from a rack flying off seem a possibility. I have travelled at highly illegal speeds (I know, shame, shame!) with a support rack & windsurfing equipment. I have complete trust in the metal attachments. Having seen carbon fibre fatigue and explode I would be more cautious. Imagine a fishing rod tip. And think of the speeds that M3 drivers go...

That said, there would seem to be reasonable engineering design solutions to the material properties. E.g., large diameter bolt attachments embedded in material with higher ductility (e.g., spectra 5000 cured in appropriate resins).
Appreciate 0
      03-24-2014, 07:50 PM   #68
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

Hey I just noticed that the Moto GP safety car has a light bar that looks to be mounted into the roof -- assume it's carbon.

http://f80.bimmerpost.com/forums/sho...7#post15659657
Appreciate 0
      03-26-2014, 12:02 PM   #69
dpmenzer
Enlisted Member
15
Rep
39
Posts

Drives: 2008 BMW M6
Join Date: Jan 2014
Location: Massachusetts

iTrader: (0)

For what it is worth, it is not possible to have a roof rack from BMW or any 3rd party for my 2008 M6 with carbon fiber roof. It is a PIA, as I can't take my Colnago's when we go on vacation. But having seen the way you can deform the roof if you over tighten the BMW mounts (on my ex-545), I'm sure you would be looking at a new $3k carbon fiber roof.
Appreciate 0
      03-26-2014, 12:15 PM   #70
mkoesel
Moderator
United_States
7506
Rep
19,370
Posts

Drives: No BMW for now
Join Date: Jun 2006
Location: Canton, MI

iTrader: (1)

But as far as I am aware the E92 M3 with the CF roof was able (and designed) to work with the OEM roof rails. So it would be nice to know what it is about the new one that has changed. Someone mentioned the CF cross brace as a possibility. It would be nice to get confirmation if that's the case.
Appreciate 0
      03-26-2014, 10:59 PM   #71
GregW / Oregon
Commander-In-Chief
2067
Rep
8,898
Posts

Drives: 2023 M2 Coupe, 2020 GLE 450
Join Date: Nov 2005
Location: Lake Oswego, OR

iTrader: (3)

Garage List
Quote:
Originally Posted by mkoesel View Post
But as far as I am aware the E92 M3 with the CF roof was able (and designed) to work with the OEM roof rails. So it would be nice to know what it is about the new one that has changed. Someone mentioned the CF cross brace as a possibility. It would be nice to get confirmation if that's the case.
I mentioned that it has them, but the rack points are above steel structure, just like on the E9X. I seriously think you could replace those 4 screws with the previous ones and be good to go. I never said that if you have problems, though!
Appreciate 0
      03-27-2014, 06:39 AM   #72
mkoesel
Moderator
United_States
7506
Rep
19,370
Posts

Drives: No BMW for now
Join Date: Jun 2006
Location: Canton, MI

iTrader: (1)

Quote:
Originally Posted by GregW / Oregon View Post
I mentioned that it has them, but the rack points are above steel structure, just like on the E9X. I seriously think you could replace those 4 screws with the previous ones and be good to go. I never said that if you have problems, though!
Exactly, Greg. The fact that the car has the same mount points located on the outer, steel part of the roof structure regardless of the roof type (just like the E92 did) is what makes it such a curious situation. I wonder what it is about the CF roof this time around that the engineers decided not to provide the mounting hardware and not officially allow the roof bars to be used.

Like you, I would guess one could put the bolts in and get it to mount up just fine. The question is what, exactly is the risk involved in doing so?
Appreciate 0
      03-27-2014, 09:45 AM   #73
dth656
First Lieutenant
36
Rep
394
Posts

Drives: e90 330i
Join Date: Dec 2006
Location: ASCII

iTrader: (0)

i'm not as familiar with anisotropic materials like carbon fiber, but i don't think that the CF (or even steel) roof panel would bear much load in normal situations. maybe some tensile and compression forces as it helps keep the roof frame "square"? any vertical loading from bikes/racks, etc would be applied to the steel structure around the CF roof panel (and the steel A, B and C pillars).

if it does fail, however, stressdoc is right: CF usually fails pretty catastrophically, as opposed to the ductile failure of steel and other metal alloys.


it's a concern for me as well--i was cross shopping the F80 w/ the new STi, and was upset to find out that the new STi may not have roof attach points either.
__________________
go bears
Appreciate 0
      03-28-2014, 08:49 AM   #74
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

I don't think it's the vertical loading (weight) that is the problem. When you crank a rack down it can exert a lot of compression across the roof -- I notice that sometimes the sunroof will not close on my E90 when I have a rack on tight. That could begin to fatigue the carbon fibre structure or perhaps even cause micro fractures on the surface resin. This could be fixed by having a rack with a cross bar attachment that could float (move) relative to the base support.

Better yet, replace carbon fibre with a proper ceramic!
Appreciate 0
      04-29-2014, 08:11 PM   #75
pbar
Captain
pbar's Avatar
1381
Rep
756
Posts

Drives: 992 GTS, Tesla M3P
Join Date: Oct 2012
Location: San Francisco

iTrader: (0)

This is *really* not good news.

I currently drive an E92 M3 and occasionally need to transport my single scull to races... (it's a 25 foot long carbon fiber racing shell weighing 10kg.)

For the past 4 years I've used roof bars on my E92 and this has worked perfectly.

I have an M4 ordered for June production and now I probably have no way to get to races.

Well done BMW.
Appreciate 1
zamboni1124.50
      04-29-2014, 10:09 PM   #76
GregW / Oregon
Commander-In-Chief
2067
Rep
8,898
Posts

Drives: 2023 M2 Coupe, 2020 GLE 450
Join Date: Nov 2005
Location: Lake Oswego, OR

iTrader: (3)

Garage List
Quote:
Originally Posted by stressdoc View Post
I don't think it's the vertical loading (weight) that is the problem. When you crank a rack down it can exert a lot of compression across the roof -- I notice that sometimes the sunroof will not close on my E90 when I have a rack on tight. That could begin to fatigue the carbon fibre structure or perhaps even cause micro fractures on the surface resin. This could be fixed by having a rack with a cross bar attachment that could float (move) relative to the base support.

Better yet, replace carbon fibre with a proper ceramic!
On the E92 the CF roof does not bear weight or stress from the stock roof bar mounting points as those are borne by the steel structure underneath. The F82 looks no different in construction. We really need an answer on this from BMW.
__________________

Greg Lake Oswego, Oregon, USA
2023 M2 Coupe - Brooklyn Grey/Cognac/CF, 6MT; 2020 MB GLE 450
Appreciate 0
      04-29-2014, 10:32 PM   #77
Reid
Lieutenant
Reid's Avatar
253
Rep
551
Posts

Drives: white cars
Join Date: May 2008
Location: HI

iTrader: (1)

Quote:
Originally Posted by pbar View Post
This is *really* not good news.

I currently drive an E92 M3 and occasionally need to transport my single scull to races... (it's a 25 foot long carbon fiber racing shell weighing 10kg.)

For the past 4 years I've used roof bars on my E92 and this has worked perfectly.

I have an M4 ordered for June production and now I probably have no way to get to races.

Well done BMW.
You should have time to change your order to a sunroof equipped car.
Appreciate 0
      04-29-2014, 10:41 PM   #78
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

The seasucker system looks good.
Appreciate 0
      05-04-2014, 05:03 AM   #79
Ragged Edge
First Lieutenant
Ragged Edge's Avatar
Canada
365
Rep
358
Posts

Drives: '16F80,TR6,Defender,PA23-250T
Join Date: Mar 2014
Location: CYVR

iTrader: (0)

Garage List
2016 BMW M3  [0.00]
Quote:
Originally Posted by stressdoc View Post
The seasucker system looks good.
Fantastic! Great find stressdoc! I will happily order the cf roof
Appreciate 0
      05-04-2014, 11:49 PM   #80
stressdoc
Moderator
stressdoc's Avatar
Dominica
616
Rep
10,854
Posts

Drives: BMW i8; Toy 4runner TRD pro
Join Date: Jun 2005
Location: Waco TX

iTrader: (0)

Quote:
Originally Posted by Ragged Edge View Post
Fantastic! Great find stressdoc! I will happily order the cf roof
Bonovox gets all credit for this.

http://f80.bimmerpost.com/forums/sho...d.php?t=977158
Appreciate 0
      05-07-2014, 10:45 PM   #81
Holset
Captain
Sweden
267
Rep
625
Posts

Drives: F90 M5 Comp LCI
Join Date: Feb 2012
Location: Sweden

iTrader: (0)

I haven't read the whole thread so excuse me if i missed something but what are these little slots if not for roof racks?


Appreciate 0
      05-07-2014, 10:53 PM   #82
GregW / Oregon
Commander-In-Chief
2067
Rep
8,898
Posts

Drives: 2023 M2 Coupe, 2020 GLE 450
Join Date: Nov 2005
Location: Lake Oswego, OR

iTrader: (3)

Garage List
Quote:
Originally Posted by Holset View Post
I haven't read the whole thread so excuse me if i missed something but what are these little slots if not for roof
Good question!
Appreciate 0
      05-07-2014, 11:34 PM   #83
Arcoril
Second Lieutenant
United_States
112
Rep
210
Posts

Drives: 991 C2S, AP2 S2000
Join Date: Jun 2010
Location: Torrance, CA

iTrader: (0)

Quote:
Originally Posted by Holset View Post
I haven't read the whole thread so excuse me if i missed something but what are these little slots if not for roof racks?
They're parts binned from the standard F30/F32. There are no mounting holes underneath based on what we've seen on uae's car:

Appreciate 0
      05-08-2014, 12:05 AM   #84
Holset
Captain
Sweden
267
Rep
625
Posts

Drives: F90 M5 Comp LCI
Join Date: Feb 2012
Location: Sweden

iTrader: (0)

Quote:
Originally Posted by Arcoril View Post
They're parts binned from the standard F30/F32. There are no mounting holes underneath based on what we've seen on uae's car:

Ok i see.
Maybe if were lucky thats just on the pre production cars and the real production cars have functional ones.
Appreciate 0
      05-08-2014, 02:36 AM   #85
crypticc
Captain
United Kingdom
73
Rep
963
Posts

Drives: e92 M3 DCT + Comp
Join Date: Dec 2011
Location: London, UK

iTrader: (0)

Quote:
Originally Posted by curehead View Post
Does anyone know if a roofbox can be installed on the M3 carbon roof? I checked out the M3 at the local dealer and it looks like nothing can be screwed into the roof, even though it has these removable flaps. My dealer did not know and is checking with the central office, but thought someone might know or be interested in this, even though this is a very specific issue.

cheers
Had anyone noticed the press out in curehead photo is in different place and not central compared to the past two above this one? I wonder if there was a spec change and then they found the holes didn't line up anymore so binned that function rather than remaking the moulds.
Appreciate 0
      05-08-2014, 02:50 AM   #86
curehead
Second Lieutenant
curehead's Avatar
Luxembourg
78
Rep
206
Posts

Drives: F80 M3
Join Date: Jan 2014
Location: Luxembourg

iTrader: (0)

Quote:
Originally Posted by crypticc View Post
Had anyone noticed the press out in curehead photo is in different place and not central compared to the past two above this one? I wonder if there was a spec change and then they found the holes didn't line up anymore so binned that function rather than remaking the moulds.
I took the picture of the rear left flap of an M3. Maybe UAE took it of one of the front flaps. I remember that the roof under the M4 flaps also looked every so slightly different. In any case, none of them had screwholes.

Last edited by curehead; 05-08-2014 at 05:57 AM..
Appreciate 0
      05-08-2014, 03:22 AM   #87
crypticc
Captain
United Kingdom
73
Rep
963
Posts

Drives: e92 M3 DCT + Comp
Join Date: Dec 2011
Location: London, UK

iTrader: (0)

But the hole should be central like the one in Alessandro's picture. Interesting your one hadn't been drilled out but the other had been but filled with a blank. Hence my thought about a manufacturing spec change done inconsistently so they just goto lowest common denominator and remove the function altogether.

Either that or its an option.
Appreciate 0
      05-08-2014, 07:05 AM   #88
mkoesel
Moderator
United_States
7506
Rep
19,370
Posts

Drives: No BMW for now
Join Date: Jun 2006
Location: Canton, MI

iTrader: (1)

Quote:
Originally Posted by Holset View Post
Ok i see.
Maybe if were lucky thats just on the pre production cars and the real production cars have functional ones.
By "uae's car", he meant "uae247's car". This is the car that is the topic of the 1000+ post thread on this forum and it is most certainly a production car.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 03:54 PM.




f80post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST