Drive shaft oil

[davidpdx]

     I am getting my bike ready for a trip down to California and while checking all my fluids I noticed that the drive shaft oil was low. It has been in about a year so I thought I would drain it. When it came out it looked like dirty milk. I did ride about 150 miles in the rain at highway speed a few weekends ago on the way to the John Day rally but I am wondering how it could have gotten in. My rubber boot has some deep cracks in it but would that let water into the drive shaft?

[Bob_Roller]

It could allow water in .

Have you checked your transmission oil, it's quite common to get water into the transmission, by the speedometer cable boot at the transmission .

Check your trans oil and see if it looks the same .

[Luca]

+1 on trans oil.  Water will fry those bearings quick.  Also, I've heard on this forum that a leaky odometer reset button can leak water through the gauge, down the speedo cable, and into the trans.  Something to worry about

The driveshaft boot can indeed let water in the swingarm, and it's the most likely suspect.  Not a whole lot of oil in there, so it doesn't take much water to make it look pretty bad.  The only other ways water could get in is past the gasket between the swingarm and final drive (not very likely) or from a leaking transmission output seal (from a transmission with contaminated oil in it).

If your trans oil level is good and the oil clean, that rules out leaking contaminated oil from the transmission.

My final drive tends to overfill a bit from the swingarm and leave the swingarm low, but the swingarm will never run dry.  Some people don't put the full spec'd amount of oil in.

[Barry]

If your driveshaft oil is a mix of oil and water and it's low, that suggests you may have lost some oil somewhere. I would check to see if any of the contaminated oil has migrated to the final drive or gearbox. Migration of oil from the driveshaft is not that unusual.

[davidpdx]

I checked both the final drive oil and the gear box oil and they both looked good and not over serviced so I am betting it got in through the rubber boot. Guess I know what I will be doing next winter. Thanks for the help.

[Luca]

In the meantime you might be able to discourage water from getting in by putting a thin film of grease over the boot and at its ends.

[montmil]

In the meantime you might be able to discourage water from getting in by putting a thin film of grease over the boot and at its ends.

Or lift the boot up and pack the interior with a marine-grade, waterproof grease.