2018-04-19 Final Drive Vent - Leak

2018-04-19 Final Drive Vent - Leak

After sitting for ~45 days on center stand, the overtime ended, time to check Uncle Dutch out. Gasp. Oil in the rim coming from the final drive.

And the wood floor is wet too.

It appeared the leak is coming from this vent hole. Not sure what volume the passageway vents. Thinking it might be the drive tube shaft, I replaced the oil with 150cc not 200cc then sprayed a little BrakeKleen in the hole. After another 5 days, no weeping from the hole, but the rim is wet with oil again.

This bike has a non-BMW final drive plug. This is the fill hole, not the drain plug.

My career as an I&C technician had me familiar with the name 'Circle Seal'. Typically, a relief valve of some type.

Thinking it might simply be leaking from the plug threads, I sourced a couple of new crush washers. Still leaked. Note that the bike is setting in a wooden building where indoor temps are hitting low 90 degrees F.

Turns out a Yamaha FJR1300 oil drain crush washer is just about perfect.

Here's the Circle Seal 4D-15 relief valve. I cleaned it, adjusted it for a low pop-off pressure (~5 psig).

I called Scottie at Scotties Work Shop but the phone connection wasn't all that good and I don't hear so well either.. but I did get the message of "I will do what I can to help! 

What I don't know is what came stock for this plug. I looked at MaxBmw fische, but that component is not listed.

My Uncle Dutch worked at Douglas aircraft. I'm thinking he found the RV, cut the threads down (look closely, it's a fine cut via machine, not a hacksaw) and this was either a hand-made nifty item or perhaps it was available back in the day? CircleSeal link.

This is a 1969 R60/2.

Hopefully someone will see this and provide some old school wisdom.. :)

Thanks for Reading,