Drive side oil seal

Doing the clutch on my T3 and as I do not want to see the clutch area for a long time will renew all the likely oil leak locations. For the drive side flange oil seal is it possible to withdraw and replace it without taking the flange housing out of the crankcase?

I’ll be doing the same job on mine soon and I hope the answer is yes.
I can’t see why not, though.

I’m assuming this is the seal :Â



Thats the one. In my Brit bike past it would have been a couple of self tapper screws in the seal and a bit of tugging. But just in case!

I’ve pulled them out and replaced them before on the basis that, if you can see it, replace it. You don’t need to remove the whole flange. I lever the old one out then oil the inside face of the new one and get it started with my fingers. I use a threaded rod in the end of the crankshaft, big washer and the biggest socket from the 3/4 drive set (50mm?). It’s chamfered on the inside just enough to push the seal in while clearing the end of the crank.

After reading the experiences of some others who have had to have 2 - 3 goes at replacing it until it’s oil tight, I would ask myself “Does it leak?” If the answer is “No”, I would leave it alone. But that’s just me. :smiley:

If it ain’t broke don’t fix it.

Thanks for the replies. Having promised a ‘no dirty hands day’ (wedding anniversary!) I did manage to get puzzled over another couple of issues
The swinging arm, complete with bevel box is on the bench awaiting a clean up. However a small quantity of bevel box oil has emerged after running downhill from the box to the UJ end of the swinging arm. Should the bevel box be oil tight or is it running out of a vent?
Also looking at the increasing pile of parts there appears to be no crankcase breather valve (the housing with the ball bearing rattling around in it). Bikes been running OK without it and the rest of the breather system looks standard, is it required?

I don’t believe there is a seal in the front of the bevel box. On my loop the oil is thrown forwards off the crownwheel to lubricate the pinion bearings. It should run back in, although a bit probably stays in the swingarm.

There is a small passage between bevel box and drive shaft tube. I presume for oil that has worked its way through the pinion bearings to return to the housing. However is moot whether this is blocked by the paper gasket at the joint. IF there is such a paper gasket of course, as there is also a big O-ring to keep it oil tight…

On the loop frame bevel box, there is a gasket between the pinion carrier and the swingarm. This has notches to match the cutouts. The O-ring is between the pinion carrier and the bevel box housing.

After a short ‘dribble’ there has been no more oil from the final drive, so I will leave well alone and check the levels frequently when its back on the road. Anyway, could not resist and pulled both rear crank seal and gearbox input shaft seal. They were tight little buggers! Thanks for the replies.

Pretty sure I put O-rings on both sides of the pinion carrier, don’t know about loop tho. But might be worth checking.