I spent about an hour disassembling (2) TOBs today; one 2013-2016 and one 2017+. Figured we would make some use out of it and share some photos and descriptions of the two since Toyobaru updated the part in 2017 and issued a TSB regarding it.
Below are some pictures along the way with what I found; along with some research I did regarding the PNs and bearing manufacturer.
The 2013-2016 bearing is from our shop BRZ, which had ~13k miles on it when we replaced the TOB during a clutch swap. The new bearing is from Subaru/Toyota, with the white dot notifying that it is indeed, an updated part.
Externally they look identical besides the white dot signifying 2017+.
Above is a photo of the non-sealed side of the bearing exposed. The PNs are identical between the two TOBs.
Here is a photo of the sealed side of the bearing once fully removed from the TOB. The PNs are identical once again (I will explain this below in further detail).
I then cut the two units apart to expose the inside of the bearing. Above is a photo I felt showed the difference in greases used well.
The white grease (2017+) felt very
Before looking at the final picture, I figure it best to describe a bit of what I found out through various PDFs published by the bearing manufacturer. It appears the bearing manufacturer only lists the physical properties of the bearing on the bearing itself; but has a vast, and much longer PN that they keep internally (or possibly supply to their customers) which describe other traits of the bearing, like tolerances, grease used, etc. The two PNs found on the bearing signify a physical size of the bearing, and then the seal used on each side. The bearing manufacturer lists 11 different "common grease codes" used in their bearings; which vary widely in makeup and operating temperature range. It then makes sense why the seals were stamped with the same numbers but the grease was quite different.
As a final "test" (read, not super scientific but it's something I could do); I took a heat gun to the two greases still in the cover. The 2013-2016 grease began to boil significantly, about 1/3 of the circumference was boiling in the picture above. The white grease did not seem to be as affected by the heat. When I turned the heat gun off, the 2013-2016 grease smoked while the 2017+ grease did not.
I believe Toyobaru honestly found the issue to be caused by grease degradation at this point. They issued a TSB for it, they updated the bearing for all 2017+ units, and the greases physically look and act differently. Only time will tell how they handle the abuse us enthusiasts put them through.
We now keep these TOBs in stock to sell with our forged clutch fork (also heavily recommended). For the remainder of August, we are offering this TOB/Clip Kit upgrade for 50% off!
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TOB Disassembly