Computer hard disk drives and car transmissions

Well, I believe many transmissions have a magnet already. If you feel the need to increase that protection I would choose one that is designed to fit snugly or attached to the pan. Metallic objects like permanent magnets sitting loose in the pan would worry me a lot.

It would be safer to rig it up to the outside of the pan...could cause all sorts of havoc if something like that broke loose inside the transmission case.

JB Weld would probably hold it just fine, and when you change the filter/pan gasket all of the ferrous shavings would be piled up right above the magnet. If you know where the filter inlet is I'd put the magnet on the opposite side of the pan to keep all of the shavings out of the main oil flow.

Chris

I found three magnets inside my Corolla's transmission pan, held in place only by their magnetism. They had 1/8" layers of filings on them, and none of these magnets were as strong as the ones found inside hard disk drives.

None that I can think of. Those things are incredibly strong. You may never get them off the pan though.