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Topic: Diff refill guidance (Read 384 times) previous topic - next topic

Diff refill guidance

I just want to confirm that once I've drained my differential I simply fill from the top (not the center plug) until full. Can someone confirm I'm not under thinking this?

Re: Diff refill guidance

Reply #1 –
I would use the center plug just more is not better. The full level is the center plug. Also check the vent to make sure it's clear.

Re: Diff refill guidance

Reply #2 –
Center plug is the level.

Re: Diff refill guidance

Reply #3 –
Got it, thanks guys

Re: Diff refill guidance

Reply #4 –
The full hole/proper fluid level on many differentials depends on the angle of installation.

I would suggest either verifying based on differential manufacturer's recommendation OR start by removing the "top" plug and feeling if that is the current oil level.  If not, remove the "lower" one.

Level is important, as it also lubes the axle bearings.

Re: Diff refill guidance

Reply #5 –
And have the coach itself level.

Re: Diff refill guidance

Reply #6 –
I thought that my fill level hole was a little lower than the axles . Some books advise driving in circles to fill the axles and recheck through the mid level hole .

Re: Diff refill guidance

Reply #7 –
The ring gear brings the oil up and the turning of the axles drives the oil out to the wheel bearings. Just like spinning a rod with a drill motor and the fluid climbs up.
 

Re: Diff refill guidance

Reply #8 –
I know you already did it but for someone's future reference, in my Oshkosh manual for the VC-22RD, it says to fill to carrier fill plug hole, which from the illustration appears to be about the same height as the driveshaft.