stevepow

I'd go for a leather wheel - they feel the best to me. We have wood in the Lexus and I hate it - hard and cold as a stone. Wood seems best in boats, not cars - although the wood in the white cab looks nice, but I'd still do a leather wheel and shifter and armrests and...ok...I'm not a wood in cars fan, I reckon.

ddub

this may be a stupid question, but does porsche use real carbon fiber and wood for these options or are they just plastic veneer? I would hope it's the real deal.

djcxxx

I had the same problem w/ my Techart carbon/leather wheel on an 06 Cayman S. It will get worse. Make a claim and consider changing to all leather. The veneer is thin and the epoxy resin heats in the sun, softens and cools. After several cycles it cracks. Carbon fiber is essentially a fabric with tensile and elastic properties based on the characteristics of the fibers. Like fiberglass which can be made w/ a variety of woven fabrics (including Kevlar), the fabric is saturated w/ an epoxy resin which can be laminated into various shapes. The epoxy resin provides the shape while the fabric supplies the strength. These laminates can be used as veneers over other materials, or as the entire part, such as a boat hull.

MyEmily

How much is that steering wheel option cost? Such as fundamental flaw / defects, Is the steering wheel make in China? Can't see the epoxy coating failed so quickly. Must have strong grip to crack it

OCBen

That's when it's used as structural material.

In the application here it is purely cosmetic -- just for looks -- and it is not being used in the typical structural material application. So I doubt the typical layup of resin and fabric is being followed. If you look closely at one of these cosmetic coverings you'll notice that the outer fabric layer has a three-dimensional look to it, which suggests that the outer layer is not impregnated with epoxy resin. I believe it's intentionally constructed this way just to create this unique look. You could do the same thing using burlap and cover it up with a thick acrylic coating. I just don't think there would be many buyers of the burlap look, or any other fabric material for that matter.

Carbon-fiber composite materials are typically used when trying to minimize weight while increasing strength, neither of which are called for in cosmetic applications.

djcxxx

Yes I understand your point OCBen. Too bad really, because even for a purely cosmetic veneer a proper layup would wear much better and it's not as though the parts were inexpensive to justify the corners cut.

OCBen

I don't really think you understand my point or understand the process here, with all due respect. There were no "corners being cut" in the production here that any of us can see. A proper layup would not wear any better here either, as the failure is clearly seen to be in the clear plastic coating (acrylic I believe) that covers the cloth material. And not anything to do with the fact that carbon-fiber cloth was being used.

Typical resins used in these composite materials have a yellowish to brownish tint and they serve to fill in the space between the actual fibers, hence the term impregnation, much like cement is used in the making of concrete, another composite material. What you see cracked is not the resin of the composite or any part of the carbon-fiber material at all. The transparent acrylic plastic, which looks to be about a hundred thousandths of an inch thick, is what cracked and failed. It had nothing to do with any failure of the underlying shiny cloth, which all it has to do is just look pretty. What little resin is being used is probably just enough to give the part its shape for ease of assembly.

If I had to speculate, I would say that failure occurred as a result of thermally induced stresses. The wheel is too new for failure to occur as a result of degradation of the plastic (decades typically). The only other possible cause of failure would be from externally applied mechanical forces, but I doubt his hands are strong enough to crush the wheel just from his grip.

So if it's from thermal stresses, what could have possibly generated enough internal heat to cause the acrylic to expand beyond its elastic limit and thus crack like that? The cloth being black may have contributed to a rise in temperature from thermal radiation absorption, but I seriously doubt this to be much of a contributing factor.

If I had to guess, I would say that what little resin was used to give the part its shape was not given enough time to adequately outgas prior to encapsulating with the plastic casing. And coupled with direct solar heating from prolonged exposure to the sun, this exacerbated the problem leading to the premature failure. Composite materials using resin outgas considerably, and enough time must be allowed for these gas levels to drop off. Maybe the supplier was falling behind on his delivery schedules and couldn't keep up with demand, and so he started using composites that weren't fully cured yet. Just speculation of course.