1981 d/shaft oil level

[crocket]

How do you check oil level in d/shaft? Manual says drain /fill with 150cc/ insert rod to top of shaft/ oil 2mm up rod ....shows OK. Then take for run  check later and oil level is way below top of shaft! No leaks anywhere unless going in g/box. Any ideas/

[Bob_Roller]

When you drained the shaft oil, did it look about the same amount of oil you put in ?

If little oil came out when you drained it, I would start looking where the oil was transferring to, usually the final drive .

If the amount of oil that came out looks to be the same as what you put in, don't worry about it .

The oil in the drive shaft housing lubes the universal joint and the few places on the drive shaft  where there is movement between the parts .

[Barry]

Manual says drain /fill with 150cc/ insert rod to top of shaft/ oil 2mm up rod ....shows OK. Then take for runcheck later and oil level is way below top of shaft! No leaks anywhere unless going in g/box. Any ideas/  

Most airhead owners ignore this official method as it tends not to work well. Just drain the oil (and as Bob said next time measure what comes out). Then put in a measured 100cc.  This is enough to provide adequate lubrication. If you put more in the excess will likely find it's way out someplace probably as mine did into the final drive.

These drive shafts are generally trouble free and one area of the transmission that you don't need to worry too much about. Just measure what goes in and what comes out. Any discoloration of the oil might indicate water contamination via a leaky rubber cover at the gearbox end.

[crocket]

Took bike for good run put on cr stand ,left 30 mins then drained oil from shaft housing 120mm came out. Refilled with 150cc new oil . Problem solved?

[Barry]

took bike for good run put on cr stand ,left 30 mins then drained oil from shaft housing 120mm came out. Refilled with 150cc new oil . Problem solved?  

You'll only know the answer next time you drain the oil and measure how much comes out. I would have put 120cc back in again. It's no big deal though just check your final drive level now and then see if migration from the drive shaft causes  the level to rise over time.

[crocket]

Did find out where excess oil from shaft was going....in g/box (must be through "vee" vent breather on bottom of g/box rear cover) so will check g/box oil level and and drain out excess.

[badbmwbrad]

At last summer's BMW MOA rally in Bloomsburg, Tom Cutter (Rubber Chicken Racing Garage) advised the BMW Owner's manual has a bad translation of the correct method to check shaft tube oil level.  

If you're filling the shaft housing from empty, add only enough oil until the actual level touches the bottom of the coupling.  The correct way to check oil level is to turn the rear wheel which will rotate the shaft coupling through the oil.  

A film of oil will coat the coupling as it revolves.  Poke a piece of wire rod into the fill hole onto the top of the shaft coupling and observe the end of the rod becomes oil wetted (the 2mm spec is just an estimate of the oil film thickness).  This demonstrates the actual oil level is just touching the bottom of the coupling.

Note - The actual shaft housing oil level is inaccessible for checking from the oil fill hole because the coupling blocks it.

How do you check oil level in d/shaft? Manual says drain /fill with 150cc/ insert rod to top of shaft/ oil 2mm up rod ....shows OK. Then take for run  check later and oil level is way below top of shaft! No leaks anywhere unless going in g/box. Any ideas/

[Barry]

Tom Cutter (Rubber Chicken Racing Garage) advised the BMW Owner's manual has a bad translation of the correct method to check shaft tube oil level.

Now that actually makes sense. And it explains why so many shaft drives have been overfilled for the last 30 odd years.