Quote:
Originally Posted by Space King
Do you happen to know who currently supplies these diffs? Are they grown in-house, or are they from Subaru (the artists formerly known as Fuji Heavy Industries) or another brand?
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I'm fairly confident Toyota manufactures them in-house. I had a chance to visit a few different facilities in Japan a couple years ago. In one museum near Kyoto they have machining equipment for making ring and pinion gears that is still the industry standard setups. Everything else in the museum was taken off the production lines, so I'd assume that is still the same case for current production. Probably entirely manufactured in-house.
- Except the bearings, They're all KOYO at least on the diffs I have had apart. Timken bearings have also been used in some OEM Toyota diffs. I have purchased one house brand pinion bearing from NAPA and it was a Koyo bearing in a NAPA box.
Toyota has a lot of cool stuff that not even other major manufacturers have - like HUGE cold forging presses. No one else I'm aware of has capability similar to Toyota to make some types of cold forged steel parts. The world is changing and those things are less common than then once were. However - Toyota can do things like cold forge gears for transmissions - making them very strong for their weight/size. They are stronger than any other manufacturing process I'm aware of and should out perform even cryo treated hot forged gears. They also cold forge many or most of the differential gears now. It's those little differences that make a Toyota last longer than any other brand, and it's easy to quantify in terms of long run reliability, but not something obvious on the show room floor.
As far as the aftermarket - I believe Circle K in Korea is the only manufacturer of aftermarket gearing for the 5th gen and every other re-brand will have the same parts in a different color box. I personally have re-geared with Revolution brand gears and they are Circle K gears in a green box. They are not equal quality to OEM Toyota gears - but they look pretty good visually. My guess is the Circle K gears are hot forged stock, so probably weaker by some margin from OEM.