CF doors by Carbon Microsystem

[usdmej]

What do you mean by that? Was it reverberating while you drove or just if you pushed against it that it would flex?

The doors are shorter so not as long of a span to bridge, maybe not the same issue in that case?

I was in a group buy organized by some E92 guys and one of them showed me on their doors. If you place your hand on the outer door skin and push in you can easily get it to cave in about half an inch (it pops back every time)

Tried it on my e46 coupe cf door and it did the same. I applied the same amount of pressure to my stock doorand it barely moved, although I suspect if you were able to cave in your metal door skin that much it would not pop back and become a dent

These doors are significantly lighter than even stripped down cf doors made by very well known brands. I don't think they'd lose any business if they added a few pounds of heft/rigidity to them

[bigjae46]

What do you mean by that? Was it reverberating while you drove or just if you pushed against it that it would flex?

The doors are shorter so not as long of a span to bridge, maybe not the same issue in that case?

Maybe flutter when driving. Long relatively flat spans of carbon needs to be stiffened with either a core or a curved structure bonded to the back. My hood only has the inner skin in the corners where the hinges bolt to. It flutters quite a bit. I can either make the outer skin a lot thicker (heavier) or add more of the inner skin like the OE hood.

[Bry5on]

I was in a group buy organized by some E92 guys and one of them showed me on their doors. If you place your hand on the outer door skin and push in you can easily get it to cave in about half an inch (it pops back every time)

Tried it on my e46 coupe cf door and it did the same. I applied the same amount of pressure to my stock doorand it barely moved, although I suspect if you were able to cave in your metal door skin that much it would not pop back and become a dent

These doors are significantly lighter than even stripped down cf doors made by very well known brands. I don't think they'd lose any business if they added a few pounds of heft/rigidity to them

Do you have door bars in yours? I don't have an idea of what the gap is like between the door bar and the door skin, but some urethane windshield adhesive could give it some stiffness back.

Would be much better to have some core material in there though, to your point.

[George Hill]

I was in a group buy organized by some E92 guys and one of them showed me on their doors. If you place your hand on the outer door skin and push in you can easily get it to cave in about half an inch (it pops back every time)

Tried it on my e46 coupe cf door and it did the same. I applied the same amount of pressure to my stock doorand it barely moved, although I suspect if you were able to cave in your metal door skin that much it would not pop back and become a dent

These doors are significantly lighter than even stripped down cf doors made by very well known brands. I don't think they'd lose any business if they added a few pounds of heft/rigidity to them

Maybe flutter when driving. Long relatively flat spans of carbon needs to be stiffened with either a core or a curved structure bonded to the back. My hood only has the inner skin in the corners where the hinges bolt to. It flutters quite a bit. I can either make the outer skin a lot thicker (heavier) or add more of the inner skin like the OE hood.

Would be much better to have some core material in there though, to your point.

My CF Roof has a fairly large span that is "unsupported" and will definitely flex if its pressed on. To my knowledge it doesn't flutter or anything like that which is why I asked about the door skin a similar but slightly smaller size. I don't know enough about CF in this application but if its not fluttering or "moving around in the wind" then what would be the advantage by adding more material?

Do you have door bars in yours? I don't have an idea of what the gap is like between the door bar and the door skin, but some urethane windshield adhesive could give it some stiffness back.

I assumed the skin would have some bonding material between it and the crash bar as well.

[Bry5on]

My CF Roof has a fairly large span that is "unsupported" and will definitely flex if its pressed on. To my knowledge it doesn't flutter or anything like that which is why I asked about the door skin a similar but slightly smaller size. I don't know enough about CF in this application but if its not fluttering or "moving around in the wind" then what would be the advantage by adding more material?




I assumed the skin would have some bonding material between it and the crash bar as well.

I imagine the primary benefit is in-cabin acoustics. Sound damping on the doors makes a big difference and you’ll have a much better time starting with a stiffer structure. Adding a core could also make it much stronger in a side impact, but that’s harder to prove/quantify.

It may sound counter intuitive but I’ll definitely be adding sound damping material in mine, so it would be extra nice to have the better starting point. Sound deadening in the doors makes a pretty substantial difference. I’ll take what I can get though.

edit: also a nicer door closing sound. Ha

[Carbon Microsystem]

Happy to see the development work!

My only nitpick from when i had my doors was that the outer skin in carbon was much more flimsy than stock, I think the touring guys would appreciate a little more material to stiffen it up at the expense of some weight

Usually we make the outer part with three layers of carbon and one layer of carbon-kevlar. At the customer's request, for an additional fee, we can make it thicker.

When we made a car for drifting, to reduce weight we made doors in two layers of carbon. The door weight was 2.1 kg

[Carbon Microsystem]

I will write a little about using carbon doors on my car.

I did not notice any difference in sound insulation. All doors are made together with internal ribs, so the doors do not rattle when driving.

The only thing I do not like is that due to the low weight, I can not always close the door the first time. There is not enough weight to press the rubber seal, but perhaps this is a feature of Toyota and so far none of our BMW customers have complained about this.

Otherwise, the doors are the same as metal ones.

Yes, the doors bend a little if you press on them, but this does not affect their strength. There is no need to compare metal and carbon, these are absolutely different materials. They should not be the same.

As I wrote earlier, we can double the amount of material in the production of doors, but I do not see any need for this. This solution is good for a carbon roof, but not for doors.

[Bry5on]

I will write a little about using carbon doors on my car.

I did not notice any difference in sound insulation. All doors are made together with internal ribs, so the doors do not rattle when driving.

The only thing I do not like is that due to the low weight, I can not always close the door the first time. There is not enough weight to press the rubber seal, but perhaps this is a feature of Toyota and so far none of our BMW customers have complained about this.

Otherwise, the doors are the same as metal ones.

Yes, the doors bend a little if you press on them, but this does not affect their strength. There is no need to compare metal and carbon, these are absolutely different materials. They should not be the same.

As I wrote earlier, we can double the amount of material in the production of doors, but I do not see any need for this. This solution is good for a carbon roof, but not for doors.

Thanks! No need to double up on material, we can always 3D scan and print/bond some lightweight plastic stiffeners to the inside if we need to. Those would do more per pound than extra layers of carbon for stiffness if needed.

[Carbon Microsystem]

The difference in weight (Kg) between a metal door and a carbon door for a BMW E46 Sedan/Touring.

The final weight of the carbon door will be slightly higher, since all the internal elements have not yet been installed.

[Carbon Microsystem]

The front carbon doors for the E46 Sedan/Touring are almost ready.

[Bry5on]

You guys move quickly!

[Carbon Microsystem]

The rear carbon doors for the BMW E46 Touring are already partially ready.

[bigjae46]

Adding a core could also make it much stronger in a side impact, but that’s harder to prove/quantify.

A core would make the part stiffer and will deflect less, not necessarily stronger. Once the part yields it will lose its strength faster. A single side impact is one thing. But if there is a side impact which causes the car to hit a guard rail, there will be no strength left in the door structure when it hits the guard rail. Kevlar will help to keep the structure together for follow on impacts.