I was curious what size rearends our 4runners have in them (the front also, while I'm asking)? Someone I work with said it probably has Dana 44's or something, but I figured they were actually Toyota design. This is my first Toyota, so I don't know alot about them.

Front is the Toyota 8” clamshell.
Rear is a Toyota 8.2”

Sizes in the names refer to ring gear diameter. A Dana 44 ring gear is 8.5 so our diffs are close.

FWIW everything i've seen suggests that the toyota diffs are significantly stronger than a comparable Dana 44. Although the ring gear sizes are comparable. the Toyota housing is much stronger and the Toyota uses much larger bearings.

For example (not my photos, but are consistent with the spec measurements so I assume they are what they have claimed they are) on the left are the inner pinion bearing from a Toyota 8.25 and the right is a Dana 44. The Toyota pinion is much larger in diameter with a significantly larger bearing at the critical point of load. I haven't done the math on the diameter vs deflection under load - but it's significant. The Toyota 8.25 pinion shaft is actually larger than a typical Dana 60. And that's the primary cause of failure under load is the pinion deflecting.



Here's the carrier bearings on left from a Toyota 8.25 compared to a Dana 44:




I believe the newest JL "Dana 44" is quite different from past generations and uses a much larger pinion as well as a larger ring gear. Dana 44 comes in many different flavors. The classic D44 is not particularly strong. The Toyota 8.25 is also an updated iteration of the original 8", although it shares no parts, the design is fairly similar. The 8.25 is probably 100% stronger if not more than the 8" or a classic D44.

Thanks guys!

Good stuff! Thanks for the share

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?

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.

Agreed. It's one of the reasons I've always respected Toyota as a brand. It's one of the few companies where the engineering department actually wins internal arguments. Honda used to be a company like that in the 80's and 90's, but they've since lost the plot, IMO.