Throwout bearing idea

[Peter Person]

At Cecil's CubFest 2011, Winfield Dave and I cut open a failed throwout bearing to see what it looked like inside. The obvious failure was the wrong grease was used and even if it had been the correct grease, not nearly enough.

What was really interesting was the "liner" that we found inside the casting. Not sure if it is a pervious membrane or not, but if not pervious, the oils in the correct grease would not pass thru into the graphite.

[Rick Spivey]

Sevy,

Thanks for answering my question. Now I know that not all graphite bearings will take the grease, so I guess I will only buy from reputable sources. I have seen or heard of many fast failures when the grease didn't do its job, or wasn't applied correctly. The dry graphite alone is not up to the job.

[indy61]

There are several European cars from the 50's and 60's that use the same type carbon/graphite throwout bearings. Such as the MG's and Jaguar E-Type. They don't have grease zerks and, from what I've read, are supposed to be installed dry. I would think the clutch is used a lot more on cars than tractors. I'm just curious why the Cub bearing should be soaked/greased? I'm not saying it's wrong, I just don't understand. This is a photo of a MG bearing.

[Gary Dotson]

I’ve always wondered if they are really graphite or a similar material. Graphite is a lubricant, in it’s own right. I’ve always assumed it to be a Bakelite material with some degree of graphite content. I’m also guessing that graphite content is not what it once was. Note that I’m only guessing.

[indy61]

I doubt any type of plastic would be used. When I look at Peter Person's photos it makes me wonder if a petroleum has weakened or had an adverse effect on the graphite. But I'm guessing also.