Lexmex

Tht would probably be the front differential, though some also call it a transfer case. Thing to remember about that one is that it drains ATF. You fill it through the tranny dipstick and eventually it will trickle down to this area and also where the tranny pan is. ALWAYS drain this (about .5 liters of ATF in there) along with the tranny drain plug when doing an ATF drain and flush. Is where the wrench is in this case, the are you were referring to?

Differential and transfer case are interchangeable terms.

chenxingha

Thanks, Lexmex. Yes, it is.

Now it explains the following: I drained the ATF through the drain hole on with the transmission pan and replaced the fluid with Toyota ATF Type T-IV from my local Toyota dealer (4 Qt., $5/pQ) two weeks ago, not knowing there is another box needs to be dained. The old ATF was black and thick. I was so glad that I changed the ATF. But a week after the change I checked the level, only to find the new ATF is dark again, with about 50 miles of driving. I was puzzled. Now this second drain plug at the front explains it all. I will do another ATF change next week - this time taking off both drain plugs!

Many thanks,

wing0

You'd have to do a drain and fill around 3-4 times in a roll just to get most of the old fluid out. You can't expect to get ur fluid back to cherry red just by doing the front diff too..

Gomer1

what he said. you will need to do it a few times (3-4)
I just did it a couple of weeks ago, and i will be doing it three more times when i drain the oil.

shawnst

are 15/16 and 24mm socket the same thing? (15/16 inches is about 23.8 mm)
I tried this with a 15/16 socket .. but it seemed not fitting the fill plug very well ... not sure whether I should use 24mm instead?
Thanks.

Lexmex

shawnst, it does use metric. I have run into the same issue where I pick up an english system tool and it doesn't quite fit.

shawnst

Thanks .. I will try 24mm.

Lexmex

When you get it off let me know if you have a lot of accumulation on the rear differential drain plug and an awful smell from the old fluid on the transfer cases.

Meetya

Guys, I have been watching this thread and your progress.
For your future reference, here is a (rare?) picture of the transfer case from above (engine is removed).

Meetya

Not quite. Although they perform very similar functions they are not the same unit. "A transfer case is a part of a four wheel drive system found in four wheel drive and all wheel drive vehicles. The transfer case is connected to the transmission and also to the front and rear axles by means of driveshafts."

Transfer case -- transfers torque between front and back.
Differential -- equalizes torque between left and right axles.
FWD RX (uses U140E) does not have a transfer case, just the front differential.

Meetya

These are official Lexus specs. Both (!) differentials and the transfer case use 75W90.

edbro

Edit: Disregard

Lexmex

Actually when this came up, members on this forum were calling what I call the front differential the transfer case and vice-versa. That was the reason I was referring to interchangeable. We have a similar issue with O2 and A/F sensors, and officially, as far as Lexus, the A/F sensors are before the main cat and the O2 sensor is after.

edbro

If the reservoir directly behind the transmission fluid pan is correctly called the front differential, why does the chart show that it hold gear oil? We've been saying that it is interconnected with the transmission and drains transmission fluid.

Lexmex

I agree with you, this is strange and I never understood this misstatement. Both the front differential (the one behind the tranny pan) and the transmission both use Type-IV ATF, not gear oil.

However, the transfer case for those of you with AWD shows transfer oil on its fill plug, and this without a doubt uses 75W90