U can take GB off together with swingarm. Same principle as working on clutch. Once you're there, my Haynes manual says it's relatively easy job to replace the seal.
Are you sure it's not the bevel box input seal that's leaking? Same symptoms (oil collects in the rubber bellows between swingarm and bevel box), but thankfully much less dismantling needed to replace
Mine bevel box smaller seal looked OK too, but it acctually wasn't "OK" - it just leaked so little, it's so called "self lubrication - they all do that sir", just had to clean the small gulp of oil after 40K, easy job, but indeed you don't have to do it if you aren't pedant like me. Or your's is massive leak?
Indeed, i understood the original question wrong - i thought you had the clutch slippy
Hmm... In your case me dunno if it's possible to change the GEARBOX OUTPUT SEAL, Haynes doesn't say anything about it's replacment, it only shows the pics of gearbox taken fully into bits
But if it's the same principle seal as the engine output's shaft seal, then it's dead easy job, no need to take off the gear box. But if not the similar one, then... as Vern says - you'll have LOADS of gearbox bits on your garage's table that day
Looks like it gets thrown to the back of the garage for a while then. I was hoping to have a break from spannering after rebuilding the bloody Airhead.
That's good news. So it is replacable on the same easy way
Make sure you don't overtighten pivot bolts (5-7Nm only for adjusting bolt and 105Nm to the contra nut for it, before that other side single bolt needs 150Nm on the swingarm's right side, both bolts are nice to be locktited) on mounting swingarm. For that very small torque 5-7Nm "feel" i clean the threads completely from the old loctite to make the movement of bolt smoooooth, otherwise you get "faulty feeling" due old glue shiite in the threads make it rough and bumpy feel while tightening - you may easily get it excessivly over- or undertightened this way.
Thanks for your help. I've done a few gearbox removals and new clutch fittings I didn't know if it was possible to get at the 1150 seal without taking the gearbox out. I've already replaced the pivot bearings and prefer to just use a standard threadlock instead of the industrial cement fitted as standard