Roof Racks with CF roof?

[crypticc]

Thread bump. Now these are coming out did anyone have a definite view? Are the bolt holes of actual production rather than pre-production cars
A). Drilled and filled with a dummy bolt?
B) not drilled at all?
C) centrally marked but off centre per pictures in this thread?

Chris

[crypticc]

? Interestingly I just completed a long driving holiday to Scotland in my e92 m3 with two bikes on roof rack (axle support for the interested).

Only when it rained hard the carbon roof picked up a nasty resonance at exactly 62 mph that only increased in pitch going faster. Needed to drop back down to 60 to remove the resonance. Didn't happen in dry weather at all at any speed.

Never occurred in my 335i coupe in any weather at any speed.

I wonder if f82 change in roof cross member to also be carbon might have caused a bigger resonance issue?

[Sedan_Clan]

Originally Posted by crypticc

Thread bump. Now these are coming out did anyone have a definite view? Are the bolt holes of actual production rather than pre-production cars
A). Drilled and filled with a dummy bolt?
B) not drilled at all?
C) centrally marked but off centre per pictures in this thread?

Chris

They aren't drilled, but they are marked. I didn't pay close enough attention to determine if they were off center or not.

[stressdoc]

I would love to see how they mounted the light bar on the Performance car.

Should have bribed Sam with a six-pack to sort that out at RA...

[crypticc]

Originally Posted by stressdoc

I would love to see how they mounted the light bar on the Performance car.

Should have bribed Sam with a six-pack to sort that out at RA...

[crypticc]

Rack mounting point for the front. But what about the back? My money is on them being off centre?

[Sedan_Clan]

Originally Posted by crypticc

Rack mounting point for the front. But what about the back? My money is on them being off centre?

American dollar or the Euro? If we're betting, I want it in American dinheiro yo!

[mkoesel]

Looking at that picture in post #83 above again, it occurs to me that the roof panel actually continues below the black trim piece where the access door resides.

Did the E92 M3 CF roof panel do the same?

I ask because, if you look at the F3x, you'll see that the nuts that you screw the roof-rail mounting bolts into are actually welded to that area of the roof panel (which is steel in that case, obviously). It seems to me that, with the CF roof, there's simply nothing to weld those nuts to. So perhaps there's nothing about the structural worthiness of the roof itself that prevents the rails. If so, it might be that they just don't support them because they didn't want to engineer an M3/M4 specific solution to attach those nuts to the car. But maybe the aftermarket could figure it out?

[Sedan_Clan]

Originally Posted by mkoesel

Looking at that picture in post #83 above again, it occurs to me that the roof panel actually continues below the black trim piece where the access door resides.

Did the E92 M3 CF roof panel do the same?

If I remember correctly it did.

[GregW / Oregon]

Originally Posted by mkoesel

Looking at that picture in post #83 above again, it occurs to me that the roof panel actually continues below the black trim piece where the access door resides.

I ask because, if you look at the F3x, you'll see that the nuts that you screw the roof-rail mounting bolts into are actually welded to that area of the roof panel (which is steel in that case, obviously). It seems to me that, with the CF roof, there's simply nothing to weld those nuts to. So perhaps there's nothing about the structural worthiness of the roof itself that prevents the rails. If so, it might be that they just don't support them because they didn't want to engineer an M3/M4 specific solution to attach those nuts to the car. But maybe the aftermarket could figure it out?

The CFRP panel mounts to flanges on the steel greenhouse sides which would seem to be under where the roof bar mounting points are. I posted this assembly pic in post #40.

[stressdoc]

Maybe a speed limiter that is linked to a sensor on the mount would resolve BMW's legal liabilities here. But damn, the smug feeling of passing lesser transformers with a Windsurfer & equipment on top is sooo sweet...

[Brady1984]

Can someone who has taken delivery of a production car please take a look and put this to bed once and for all?

[mkoesel]

Originally Posted by GregW / Oregon

The CFRP panel mounts to flanges on the steel greenhouse sides which would seem to be under where the roof bar mounting points are. I posted this assembly pic in post #40.

Right Greg, but what I'm saying is, if you take a look at the F3x, the nuts are welded to the roof panel itself. And since you can't weld to carbon fiber, obviously, we get no nuts on the F8x with CF roof.

So, my question is, how did the E92 M3 get around that?

Originally Posted by Sedan_Clan

If I remember correctly it did.

Ok, so if that's the case, what did the roof rail bolts screw into?

[Sedan_Clan]

Originally Posted by mkoesel

Right Greg, but what I'm saying is, if you take a look at the F3x, the nuts are welded to the roof panel itself. And since you can't weld to carbon fiber obvious
Y, we get no nuts on the F8x.

So, my question is, how did the E92 M3 get around that?



Ok, so if that's the case, what did the roof rail bolts screw into?

Good question! I no longer have my E9X to take a look, but I've seen many, many E9X M3's with roof racks.

Maybe this thread will help: http://www.m3forum.net/m3forum/showthread.php?t=442651





...and this guy is bold

[mkoesel]

^^^ love it!

I read back through the thread and Greg posted a picture of his E92 mounting nuts in post #51 (thanks Greg). It looks like the nut is actually the head of a bolt that itself screws into something else (?).

So we have a variety of pics in this thread:

- E92 M3 mounting point (post #51)
- F8x with bolt in mounting hole (post #41)
- F8x with no bolt at all (post #17, #83)

It would be great to get E90 (or E92) and F80 3 Series pics too. I suspect the E90 looks like the E92 M3 in post #51 with a bolt that has a threaded head, while (as I said in my earlier post) the F80 has a nut welded on. I think that's the reason for the change in support for he rack with CF roof.

[stressdoc]

It's hard to tell from the photo of the light bar, but a couple guesses: First, it looks like they use the front mounting point -- for sure we can see the rear mount flap. So there is some way to install an anchor in the existing spot in the front mount, perhaps similar to the implanted threaded star bolt in the E92 M. Second, the mount on the light bar seems to have just one bolt (like the E92 M), but cannot tell without a better close up, ideally of the inside of the mount to see what the anchor looks like.

[mkoesel]

Agree, stress, it does look like they've made use of the front rack mounting point.

The thing is, this is a one-purpose car so they may have just drilled straight through the whole roof panel and rail assembly and put a bolt through into the cabin. Though I'm obviously speculating, the point is, it might not be suitable for us. Also, that's just a light bar so it doesn't confirm that the roof is up to the task of bearing a heavy load.

Still, I agree it would be great to see just what they did there.

Edit: you know, on closer inspection, that light bar is pretty far back and quite near the rear mount. Looking at the E92 pictures above, it appears that the front mount would likely be closer to the A pillar on the F82 than where the light bar is positioned.

[shivaswrath]

Originally Posted by Kanuck

I know I will be flamed for even asking this question, but for the occasional time I want to transport bikes with new M3, does the CF roof have the fittings for a roof rack?

LOL id flame them back, M3 has a mechanical diff dammit=snow traction power!!

There are little flip covers on the CF roof, BMW gets us :-)

[stressdoc]

Originally Posted by mkoesel

Agree, stress, it does look like they've made use of the front rack mounting point.

Edit: you know, on closer inspection, that light bar is pretty far back and quite near the rear mount. Looking at the E92 pictures above, it appears that the front mount would likely be closer to the A pillar on the F82 than where the light bar is positioned.

We should be able to pin this down by comparing photos. The rear flap is visible; the light bar is not that far from it, but I don't have a good sense of how much distance there is between the rear & front flaps. Makes sense that they would optimize location of the light bar rather than worry about pre-existing mounting points.

It is indeed a special car, and has a ton of serious mods like a roll cage, so this may be a one-off deal where they just drilled through the roof... But it might indicate something about the feasibility of modifying the roof ourselves if the light bar mounts work at high speeds without affecting the roof.

[minus9]

I stopped by a local dealership at lunch and they had their launch M4 on the floor.
The front and rear roof slots were there, but neither had threads in them.
Here is a phone photo of the rear:

View post on imgur.com

[crypticc]

Originally Posted by minus9

I stopped by a local dealership at lunch and they had their launch M4 on the floor.
The front and rear roof slots were there, but neither had threads in them.
Here is a phone photo of the rear:

View post on imgur.com

Ta. There's a definite 'impression' there. I reckon BMW changed their mind for some reason.

On my e92 the threaded bolt receives a bolt with threads at both ends. The shorter of the two threads pulling into the car and the longer standing proud to receive the roof rack. The feet of the rack itself offers over that and settle either side of the bolt. A nut pulls onto the bolt and in doing so pulls the feet into the STEEL directly below the flap. That material we see under the flap is what takes the load both uniformly and twisting.

This is pure guess work but I would think BMW found the forces involved would shatter CFRP and so removed the hole to receive the threaded nuts you'd get in an e92. It may have been late enough I'm the design for them to tweak target than redo the roof molds completely. We get to see a piece of the original design through that flap.

What a shame. Nothing like cooler than a performance car with loads of sporty gubbins on a roof rack. Oh and it's useful too.


Chris

[SoN][c]

I specifically asked a sales person if a roof rack could be installed and he said yes. He showed me the mounting points that you can see in this pic. The flap opens up on each side and I suppose there is a connection mechanism that locks in: