View Full Version : T90 Transmission and Dana 18 Transfer case Lube Levels

06-03-2020, 07:03 AM
The T90 / Dana 18 transfer case assembly has a "balancing" lube system. The transmission gear case has an internal lube hole shared with the transfer case. The level in the transfer case is lower than the level in the transmission. As the transfer case gears rotate, they lift the lube up to the shared lube passage in the transmission. This sort of refills the transmission case. When the transfer case gears stop rotating, the lube drains back from the transmission to the transfer case. So if you drive it and it losses lube from the transfer case, the trans will keep filling it. The transmission will steal a lot of lube from the transfer case if it (the transmission) is leaking. It is a good idea to keep an eye on both levels.

Here is a good image from the CJ2A page.

Carson Childs
07-20-2020, 11:51 PM
That's a very detailed explanation of the "balancing" lube system. Might as well check out the CJ2A page. I might see more of these illustrated descriptions.