Mainshaft oil seal change

I've got a wee oil leak from the main shaft oil seal Has anyone changed the mainshaft oil seal with the box still in the bike. If so what was your method and are there any pitfalls to watch out for?

Ugh, blind folded now if a simple 750. Open primary, get slack in chain, remove alternator, empty clutch guts, lock up parts to get basket nut off and crank nut, torch & puller off crank sprocket, run a self tap/sharp sheet metal screw or two in to jerk seal out then, as manual says, just reverse your way back out, minus the sheet metal screw part. Don't ever over tighten 1' chain is main danger. Not getting the 3 small inner case bolts to stay put oil tight long term is more minor risk disturbing those sleeping tight puppy's. Not a bad id to smear a favored sealant in with the seal. Getting the peddle out the way is bothersome and risks stability of the delicate brake wiring and switch function. MIght as well put on a brake safety spring too if not already.

Getting the primary off and out the way is not a problem I was just wondering about getting the seal out and a new one in. What did you use to fit the seal back into the case in again?

Pretty straight forward actually. The primary comes off completely, of course. Then the drive sprocket, which has a left hand thread. I usually engage 4th gear and lock the rear brake to remove that. I believe it's 1-1/2" but the real problem is that the mainshaft is too long to get a socket on it, even a deep impact socket. The standard sockets are just shy of the 3-1/2" that you need. My buddy bought a socket off Amazon that I think is 4" deep for reasonable cost.

After that, there is a steel spacer between the seal and the mainshaft. You need a couple of dental picks to pry that out. Check the outer surface of the spacer for wear groove, and replace it if you feel one. Otherwise a new seal won't last long.

Then the seal itself comes out, being pried and rocked with a couple of small screwdrivers.

Replacing the seal you need something to keep it from cocking as you tap it in. I use a block of wood with a hole for the mainshaft and the socket as a spacer then tap with a mallet.

Ugh not just crankshaft, opps. Can use a super magnet to get the big thick spacer out too and helps grab steel clutch plates out as well. Buggaboo is locking up parts with sticks in spokes or tying rear brake peddle down or vice grip on final chain or clever sized blocks/plates that trap in basket teeth and primary mount post. I find a 1.5" end wrench works find remember the altert its reversed threaded. Also I can't see the sense in 70 lbft on it as nil sliding out off shaft loads to resist and its locked on slpines in place by the lock ring.

The spacer on the inner lip of the seal can come out and on mine I just grabbed the seal with my fingers and it came right out. I put the new one in with some gray Hondabond smeared on the outer surface. I used a piece of PVC pipe to seat the seal. When putting the primary back together I pulled the engine sump plug and let the oil drain out. Then sprayed some Bra-kleen in the 3 holes for the inner cover and cleaned them out really good before putting the bolts back with more Hondabond. This oil dribbling pain in the ass can be avoided by going to studs and nuts there instead of bolts which I now think is probably a good idea. (I didn't do it though.)

Dave said:
"Check the outer surface of the spacer for wear groove, and replace it if you feel one. Otherwise a new seal won't last long."


+1
If you go in that deep and don't also change the 04-0131 spacer (they are not hardened). They are not that expensive compared to doing the job again in a short time.

I certainly learned my lesson........the hard way...I always keep a seal AND spacer as spares :mrgreen:

All stripped out now and like you guys mentioned the spacer does have a pretty good groove round it, so I'm guessing that'll be the cause of the wee leak. Parts ordered from RGM at 15:45 and I had an e-mail back from them at 16:11 to say parts had been dispatched, now thats service for you. I'll have to wait another 3 weeks to put it back together though, something called work got in the way.