Gear box Seal

[wally]

Hi, Hoping the answer is no; do I need to remove the engine from my plunger, engine number A10 12229 to replace the gear box/chain case seal? On the side stand oil leaks into the clutch. Is there a quick fix?   Regards to all.

[duTch]

 Yes.... - for impending sorrow

....however...(and the answer is likely still not 'no'),.....

 If oil is leaking into the chaincase, only place I can see it's likely coming from is the gearbox through the sleeve bush, so the only way to fix that is pull the motor/g-box out...and the box apart.... ...or from the engine crank seal you can do by just removing the engine sprocket/cush drive...
 On the other hand, if oil is leaking out from the chaincase, I think you still need engine/box out, same if it's the Gear box seal as the topic title suggests...

 unless with the gearbox seal/sprocket you have a mod., like the unit models- with a removable seal plate.
 

[morris]

In my world quick fixes usually end up in big fixes....

Have a look at the gearbox oil level though.
If, as Dutch suggests, oil is leaking via the main shaft when the bike's on the sidestand, the box may be overfilled

[duTch]

 Actually, I just rethunk that a bit- the sleeve gear/bush doesn't go through the seal anyway, stops shy of the case, so the only place extra oil comes from must be the crank...? (in which case the answer would be 'no'- you may get off lightly)
 
You say "oil leaks into the clutch', not into the clutch/chain case ? Do you have the cover on the basket ? (I don't, and I think it's unlikely much oil would reach the plates, with centrifugal action flinging oil away, and the cover flange- even without a cover- would inhibit much oil flowing in at standstill..?  )

 curious...maybe just too much oil in there.!
 

[muskrat]

G'day Wally.
The only way g/box oil will enter the clutch is via the clutch push rod. Doubtful. Primary case oil will find it's way in via the rollers, but only a small amount.
The most common problem with plungers is a wet sumping motor will allow engine oil to enter the primary when the level in the sump reaches the crank, and starting with a full sump will pump it in then leak everywhere. My plunger will do it if left sitting on the side stand for a few weeks.
Cheers 

[wally]

Hi Everyone & thanks for your advise. I've pulled the oil soaked clutch basket off, discovered the 18 rollers, the roller backing plate & a split circlip behind which is a tin plate held on by 3 rivets. This plate seems to hold a fibre seal & I think through this seal is is where my gear box oil is going. I didn't over fill the box, just until oil ran out of the hole on the back & now the level is very low. It looks like engine out &, after searching old "topics," rather than re-riveting, small nuts & bolts with Loctite is the way to go. As to where to buy the seal, I guess Aussie is the closest.

Regards, Wally       

[Brian]

Wally even if the seal behind your clutch is worn out as Muskrat said the gearbox oil still can not get into the primary case. If gearbox oil is leaking past the gearbox seal or sleeve gear it will run down the gearbox and back of the primary case and onto the ground.

If you are getting oil in the primary case it will be coming from the engine. Depending on what year your bike is it may or may not have a seal on the crankshaft behing the cush drive. I think they fitted the seal from 1953 onwards. This seal can be easily replaced.

The seal behind the clutch you will be able to get from any bearing supply place, its a common size. I cant remember off hand just what size it is but it will be imperial, there is a metric equivalent that can be used.

[wally]

Thanks Karma, It's not oil in the primary case I'm worrying about, it's oil into the 'top hat." It may be, as suggested, coming down the clutch rod hole. I'll double check the box oil levels. I will remove the engine & fix that seal, it's been 30 odd years since it was last out.

Regards, & thanks again, Wally

[wilko]

No more advice. Find out the hard way. You've made up your mind.