I recently got a 1944 M20 and I was changing out all the oils for it. I did the primary chain case, oil tank, and then the gearbox. The manual says 1 pint for the gearbox so I did about 550ml. I didn't even notice at first that my oil was quickly overflowing from the top of the fill hole. It seemed the gearbox couldn't take anywhere near that much oil so after it was full I just drained a decent bit out then closed it up. Anyone know what if the capacity isn't actually 1 pint or if something else could be wrong? I would imagine over-servicing the gearbox could damage it. Also I did indeed verify I was refilling the gearbox (lubrication point 14 in the chart within the manual.) Any advice or information would be greatly appreciated.
It says 'KEEP FULL'...Fill it up until the oil is part way up the filler 'spout'....You won't get a full pint into the gearbox...If you don't have a sealed bearing fitted at the drive end of the gearbox check the oil level frequently as it can drop very quickly, particularly if the field stand is used regularly.....About every 250-300 miles...Ian
That's embarrassing if my cap really does say that and I never noticed. What seal bearing are you referring to? That must be what's happening because it's leaking out a lot and it is currently on the field stand. It sounds like I should buy one and install it. I appreciate the patience as I am new to this bike and I'm trying to learn to fix it up.
Christien what some of us do during a gearbox rebuild is replace the open ball bearing at the drive end with a double lip sealed bearing. (It's a standard replacement)
Personally I remove the inner seal (it just hooks out with a thin screwdriver) so that lubrication to the bearing is as standard. (Others have a different opinion about that)
The bearing number is 6205 2RS....'2RS' refering to 2 rubber seals....It's a metric bearing so readily available from any bearing supplier...It's not something that can be easily fitted, requiring the removal and complete strip down of the gearbox...
I would say best done at a time when the gearbox requires other work...Ian
Thank you all for the information! I think I'll make a different post about bearing selection then because there definitely seems to be a lot of different options.
My apologies..I gave you the wrong information....It's a 6207 2RS...I don't know how I got that wrong, I've built scores of those gearboxes!!..:blush: ...Ian
