What's wrong with this clutch and flywheel?
(hope you don't have one of these in your car!)
Recently, we have seen hybrid clutch options from some vendors. This design consists of organic material on one side and a segmented carbon or ceramic material on the other. The idea is that the organic side will help smooth the engagement, reducing the shuddering that one would expect from the segmented side.
On generally accepted principle, any chain is only as strong as the weakest link. With that in mind, temperature and hp range of this hybrid clutch is identical to organic. It would not matter if the carbon/ceramic side were more durable, the entire assembly is subject to the limits of the organic side. Therefore, no racing or slip-resistance advantage at all. As carbon/ceramic side will wear flywheel or pressure plate surface faster (even moreso in traffic situations), there is a distinct disadvantage to this setup.
Gimmick? Quite likely. The "hybrid" design appears to be more of a marketing hook rather than an actual performance advantage. The brand we examined, although it still functioned, was on the way to failure due to bad design. Flexation of the underlying clutch disk caused uneven wear of the carbon/ceramic pucks, and was not sufficiently stiff to hold the solid organic side against the pressure plate. While the underlying structural disk might have been sufficient for a full-area friction material, it clearly was not when built with the puck design.
Unless requested for "safety check" purposes, we have kept the vendor of this setup anonymous. All manufacturer markings have been blurred out
Ever wonder how to turn over $1000 worth of flywheel and clutch in to scrap? Follow these steps...
Click any pic for a larger view.
Carbon/ceramic side of clutch disk. Note individual pucks. These are the friction areas on this side of the disk.
Note excessive scoring. This clutch was mated to an aluminum flywheel with an inferior grade of steel for the friction surface. The flywheel vendor sold this clutch as a package with the flywheel, quite obviously unaware of the material characteristics. Note the scoring on the pucks.
Another view of the pucks showing scoring.
Either inferior flywheel material or flexation of the clutch disk caused dramatically uneven wear of the flywheel. Note the difference in material thickness between the inner and outer diameter. With only 6,000 miles on this clutch, it is doubtful that it would have reached 10,000 miles before failing completely. This is the "matched" flywheel. Note the blue discoloration of the friction surface's outer diameter from heat and wear. A high-grade steel friction surface would not have suffered this damage.
Like all aluminum flywheels, this unit has a steel plate bolted to an aluminum disk. However, note the placement of the 12 bolts. See that large areas of the plate are not fastened. Under high heat, this will allow the plate to buckle and lift, decreasing contact area and causing abnormal wear. That problem is also one possibility as to why the inner and outer diameters are "blued" with heat to different degrees.
Close-up view of the friction surface. Note the deep grooves. This flywheel friction surface is beyond repair. This is the opposite side of the clutch disk, the solid organic side. Note the alternating shiny and dark areas, eight of each. Not coincidentally, there are eight pucks on the other side, whose positions correlate to the shiny areas on this surface.
What we see here is the structural clutch disk plate flexing, causing the dull areas to avoid contact with the pressure plate. Effectively, only half of the organic side was in contact, meaning the other half (the shiny areas) were exposed to twice as much friction.
Same pic, circles mark the areas that were not contacting.