Hardy disk failure mode

[Allan Atherton]

I had seen how the old Vulcolan disks failed. The black rubber with fibers would break and crumble. But I had wondered how the new urethane or nylon disks would fail. (I don't know what they are made of.)

Yesterday I saw what appears to be a new-style disk that was failing. Instead of being tan like my new disk, this disk was pinkish- or reddish- tan. Several of the lobes were eroded at the drive pins, with missing material. The material had not worn away from inside the pin holes, but instead it had chipped away. I poked the eroded areas with a screwdriver, and the material of the disk felt like very hard swiss cheese. I could remove some more material on the tip of the screwdriver.

[Curt]

could all these squeaking discs be from one old supply that was inapropriate for the application and/or aged by heat and/or time in storage?

[Allan Atherton]

It is normal for the Hardy disk to sqeak. If not lubed with anything, the steel drive pegs rub hard against the rubber or urethan disk. If lubed, the noise is greatly reduced but I think there must always be a squishing sound as all those drive pegs revolve and go in and out of the disk.

[Allan Atherton]

Also, my hard tan urethane plastic Hardy disk was installed in 1998, about 10,000 miles ago, and is still good. I used a little grease then, don’t remember what kind, maybe bearing grease, maybe dielectric silicone, or maybe vaseline. And a few years later I used a spray can with a wand to shoot some white lithium grease into the holes in the disk.