Oil Change - Transfer box/overdrive

Technical questions and answers
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Joined: Sun Sep 30, 2012 6:40 pm
Location: California

Oil Change - Transfer box/overdrive

Post by llandes »

Question for those more informed than I...

I read somewhere that when topping off or changing oil in the transfer box, one can simply top off the overdrive (if fitted) and that would also top off the transfer. Made sense until I tried it a long time ago.

Two things happened:
1. Oil did flow from the overdrive into the transfer box, but VERY slowly. Waiting for this to happen would have taken hours or days.
2. The plug in the transfer box (the one to be removed, so when full, oil will seep out) is lower than the drain plug on the overdrive unit. This made no sense to me.

It's time to top or change fluids again as I drive my Stage 1 a lot. Am I missing something or was the original theory I read correct?

I'm not understanding how the drain on the overdrive can be higher than the upper plug on the transfer box, and how the theory would work. Conversely, if I top off my transfer box separately, and then top off the overdrive (which is higher), the oil will slowly flow from the overdrive into the transfer box. In the end, it seems the transfer box level would be too high and what should have been oil in the overdrive would have slowly flowed into the transfer box - making the overdrive low on oil.

I'm confused. Can anyone set me straight?

Thank you.

1983 Station Wagon, LT95, Overdrive.

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