I'm not trying to put an SSD in the optical bay. As I said, I've tried multiple HDDs but none of them seem to work. I know that it's possible to put an HDD in the optical bay because I bought the computer with one in it but it seems that none are recognized. I have tried multiple brands and speeds with no luck. I would like to know which specific model of HDD works in the late 2011 15" optical bay.
I'm experiencing the same issues with the HDDs in the optical bay. I've tried multiple drives (WD caviar blue 3G and a Seagate 6G) with no luck thus far. I replaced the SATA cable and that didn't help with either drive. My SSD still works fine in the main bay but I would like the extra storage.
For those of you who got the HDD in the optical bay working, which HDD (brand and model) did you use?
My MBP is a Late 2011 15" (8.2)
If I'm understanding you correctly you want to replace the HDD with a larger capacity drive. In that case, for the most part, it won't improve the performance dramatically. A solid state drive would be the biggest improvement in terms of drive speed. The overall storage size won't really speed up the machine it will just give you more room for programs and storage.
Hope that helps,