Plunger gearbox oil seal

[Tone]

Guys, it looked like the gearbox sprocket oil seal has gone on my A10 plunger, do you have to take off the primary side, clutch etc as well as the gearbox to change said oil seal? Thanks Tone

[duTch]

 Yep, afraid so- engine out.....unless you've done what I did and cut a hole in the inner primary case utilize a sprocket cover plate from the 'Dark Side' A65. I have a photo somewhere, I'll see if I can find it.
 But even with this in place, unless you know magic  you'll still need to pull the clutch off (as I do).

 But before you go berserk, does it just leak when it's on the side stand? If so it may be leaking via the sleeve gear as I think mine does, but I kinda fixed that by parking the bike leaning RHS against the house, or if you have a centre stand fitted, sit it up on that for a while after a ride and see if it still leaks as much (in this position the oil level shouldn't be high enough to keep leaking).
 

[Tone]

I've done some more reading up on the plunger gearbox, and it seems mine might not have an oil seal at all ! But a scroll on the inside of the sprocket that throws oil back into the gearbox, if that's the case I wonder if someone has put on the wrong sprocket? Also is it right that you have to take the engine and gearbox out of the frame together, even to change the sprocket?? Or can you get to the sprocket through the primary side? Sorry for all the questions, it's the first plunger I've had, and I don't want to go charging in taking bit off that I don't need too! Thanks guys, Tone.

[duTch]

Also is it right that you have to take the engine and gearbox out of the frame together, even to change the sprocket

Yep, afraid so- engine out....

              ^^^^^^^^^^^^^^^

 

I've done some more reading up on the plunger gearbox, and it seems mine might not have an oil seal at all ! But a scroll on the inside of the sprocket that throws oil back into the gearbox, if that's the case I wonder if someone has put on the wrong sprocket?

 I'm no expert, but I've been led to believe the box with no seal, and sprocket with scroll were fitted in A7 longstrokes and early A10's to '~50,  not to say that it hasn't been done to yours, but I'd riskily say unlikely. I think there was discussion not  long ago that the scroll sprockets aren't available, and anyway, why would you bother except for 'original'. The seal should go straight in (more or less- some have had trouble). I am using one of these boxes, and have fitted a seal- in fact changed it a couple of weeks ago, that's why I can sound so pretentiously 'knowledgeable'
 
 

Or can you get to the sprocket through the primary side?

 NO, regardless what version you have

unless you've done what I did and cut a hole in the inner primary case utilize a sprocket cover plate from the 'Dark Side' A65. I have a photo somewhere, I'll see if I can find it.

Sorry for all the questions, it's the first plunger I've had, and I don't want to go charging in taking bit off that I don't need too!

 That's ok, and I'm sure someone will clarify my ideas, but;
 

...before you go berserk, does it just leak when it's on the side stand? If so it may be leaking via the sleeve gear as I think mine does, but I kinda fixed that by parking the bike leaning RHS against the house, or if you have a centre stand fitted, sit it up on that for a while after a ride and see if it still leaks as much (in this position the oil level shouldn't be high enough to keep leaking).

  Try that ^^^^ first,  If it is an early scroll type, I'd say it will leak on the side-stand until it loses what oil is in the bearing cavity, regardless, but I've never run that system this box of mine was a spare and I used a new sprocket and seal anyway.
 You're only guessing, and thinking the worst, which is not so bad anyway and if you think you need to buy a new sprocket (and seal), you won't know for sure until you pull it apart, so if you have it and just change the sea not the sprocket, you'll have a spare for later.
   It's not hard, a bit more than a ten minute job, so just need to allocate a day- help is at hand .

[Tone]

In the book I was reading it said there was no oil seal before frame number whatever, and my frame no was before that so until I take the engine out I'm only guessing, but if it has no oil seal are you saying there is a recess to fit one anyway?

[edboy]

hi tone , this happened to me also. a late swingarm oil seal will fit straight in . i also renewed the gearbox sprocket and cant remember if old one was different. you must check.

[trevinoz]

Fit the later seal but you have to use the later sprocket without the scroll.

[Tone]

Thanks guys, is the plunger sprocket the same size as a swing arm one? And am I right in thinking its 19 teeth?

[duTch]

 Yep, same sprockets, 19 is fine, but  I'm thinking to go to 20T for longer legs.
 If the rear is 42T standard, unless it's had a sidecar would likely be 48T, same through to '57 or '54-'55 S/A.

[Tone]

There is still a 48T sprocket on he rear, will sprockets from the later swing arm go straight on the plunger?
The parts book lists the oil seal 67-3067 as being the same across all the A group, that makes it easier.

[duTch]

 I did my best to explain in my previous post