Dubai Build (& CF Roof Discussion)

[Jake]

Just ran across this during some lazy surfing. I searched here but didn't see it posted so here it is.

http://www.crankandpiston.com/201112...-perfection-1/


Kind of interesting.

Jake

[JOEBMW]

Interesting build for sure. I am curious to see the final product.

[xworks]

Good find Wonder how much the carbon roof would cost?

[Ironhead]

Yeah, builds like that make me jealous. That thing will cost well over $100K before it is done.

[Jake]

IMO, a CF roof in a caged car makes more sense than a CF drive shaft. I don't know why we don't see it more often. I have a new steel roof in storage I've always wanted to get copied in CF. It's a fairly simple piece to copy, but the fab work to install is not for the average Joe.

Jake

[///schwartzman]

IMO, a CF roof in a caged car makes more sense than a CF drive shaft. I don't know why we don't see it more often. I have a new steel roof in storage I've always wanted to get copied in CF. It's a fairly simple piece to copy, but the fab work to install is not for the average Joe.

Jake

Nice find, thanks for sharing!

I agree, the lower CG from the CF roof would improve the handling on M3 greatly and the ease of installing the cage would be a godsend. I view the driveshaft as serving a similar purpose in the grand scheme of things, analogous to potential & kinetic energy, respectively. I'm pretty sure Keith @ Competition Concepts could do it with his experience with bikes etc. Jake is your roof an M3 spec non-sunroof?

[Jake]

Hi Rich. IIRC the roofs are the same. Its just the upper skin and only extends down the pillars an inch or so, but it does continue under the rear window cap. I'll take a closer look when I get home. I'd happily provide it as a sample if someone wanted to make a mold.

Jake

[Jake]

Pics from the article. The new non-sunroof top I have appears to end at the same point this CF top stops.











Jake

[Brendan]

IMO, a CF roof in a caged car makes more sense than a CF drive shaft. I don't know why we don't see it more often. I have a new steel roof in storage I've always wanted to get copied in CF. It's a fairly simple piece to copy, but the fab work to install is not for the average Joe.

Jake

CF can be a DIY if you take your time... Not BMW content, but good reading if you're looking for inspiration:

http://forums.corral.net/forums/lounge/660756-sub-2500-lbs-96-mustang-cobra-project.html

- Brendan

[Mike K.]

CF can be a DIY if you take your time... Not BMW content, but good reading if you're looking for inspiration:

http://forums.corral.net/forums/loun...a-project.html

The roof is a very large section to tackle if your not experienced in vacuum forming parts. Also as the link points out, you spend a significant amount of time on a mold to make one part. Laying up the roof may take a couple of hours, but you'll have 80 - 120 hours in making a proper mold. Also you'll need some type of structure to prevent the roof from vibrating on the track & ripping itself out of the car.

My FG hood vibrated so bad that we where taping the leading edge to prevent it from ripping off at 120 mph. We did reinforce the underside with CF & marine foam to stop the problem. Venting was the next step.

Mike K.

[Brendan]

I didn't say it wouldn't be a lot of work. Like a lot of things - it's pretty straightforward if you think about it, but VERY time consuming...

Another thing the link points out - he is completely self taught in composites, etc. He's pretty much a gearhead like a lot of us.

Brendan

[Jake]

I'd glue it to a vertical rib off the main hoop. That plus its natural convex shape should keep it stable at speed I should think.

Jake

[TR-Spider]

I agree, the lower CG from the CF roof would improve the handling on M3 greatly---.

well, no it would not. Maybe marginal, but no way "greatly".
Simply as it lowers the CG not much.
That is one of the myths around...see http://www.s14.net/forums/showthread...highlight=roof

This carbon roof skin is kind of a fashion item, however, it's a nice one.

Thomas

[///schwartzman]

Ok, the physics of this CF vs sheet metal center of gravity debate can go on and on. In the case of most e30 M3's my point is, we would lose the weight of all sunroof parts, in addition to less than half the weight of the steel counterpart. Factor in the added rigidity the benefits become more than just a static calculation. It could foreseeably reduce the necessity for adding other (weight) bracing, while dynamically improving handling.

Cues from the McLaren F1 and a host of modern day CF monocoque designed cars are using the exotic material for its reduction in weight, increased strength & rigidity for good reason. We'd have analyze dynamic roll / track data including lap times to assess the benefits attributed to the addition, but what is undisputed however negligible has been proven, thus not myth, fact.

All in all, if one can afford to have it done right I'm an advocate. I was taught in physics "weight is the enemy of speed!" (acceleration, overcomming gravity and the whole enchilada... And it's damn sexy, painted or not.

[Brendan]

Ok, the physics of this CF vs sheet metal center of gravity debate can go on and on. In the case of most e30 M3's my point is, we would lose the weight of all sunroof parts,

You can lose the sunroof parts pretty easily without replacing the roof skin. My car has just a single metal skin welded / bonded in with the entire inner cassette and all bolt on parts removed.

Rigidity won't be an issue for an already caged car.

Really - it is pretty fricken cool, but there's other places where it'd make a much bigger difference. I'd be interested to remove the entire front radiator support and fit a removable CF front clip forward of the struts. Now that would save some weight out front...

- B