1976 Commando 850 MK3

Yes you can. Pry out the wire circlip first. Take care when installing, there is no flange where it can sit against! Degrease thoroughly, use a wee smear of loctite for proper sealing and locating, and drive it in nice and squarely just so far that it clears the groove for the wire. Bennie.

Ian, it is possible, but it's not so easy to do a good job on the Mk3 as it is on the earlier models. The seal on the Mk3 is retained by a circlip - not a Seager ring as per the factory illustrations but a simple wire clip which can be a bit of a fiddle to get out.

Depending on whether your old seal has been spinning, it can be removed by fiddling with a small screwdriver or a pointed hook pushed through the rubber part. You may find it possible to force a small self-tapping screw into the seal which will make it easy to remove with pliers. Drilling prior to inserting the self-tapper is not something that I'd want to do as inevitably some of the swarf will migrate into the main bearing.

The Mk3's special difficulty comes with reassembly. The earlier cases have a shoulder behind the seal and after being pushed firmy home, it will automatically be sitting square. The Mk3 with its wider crank does not have this shoulder which means that the seal can be pushed in until it touches the main bearing which is obviously too far and will cause the seal to spin with the bearing.

My preferred method is to use seals with a steel outer surface. Degrease all components thoroughly (the cases with a cotton bud or somesuch). I then put a smear of 'Bearing fit' on the seal and carefully enter it in to the housing, follwed by the circlip which I then gently push, a small amount at a time until it expands into its groove. The seal should then be sitting square - If not, you'll have to take it out and try again. The seal is very narrow for its diameter and has the tendency to go 'over-centre' as it's pushed.

I probably should mention that I like to have a couple of spare seals handy. Sod's law dictates that if this isn't done, then the seal will go in crooked and destroy itself during removal.

Good Luck !

Rich (Amateur tinkerer).

Although I have not tried it, I would be hesitant about using a bonding, hard curingsealant. In case one hasto replace the seal againlater on, one has to break the bond to get the seal out, and than clean the sealant remains in the bore, all this right next to the crankshaftbearing, and in a veryawkward position. Igo for theacetic cure type of sealant (with thevinegar smell), it will keep the oil out and remains areeasier to clean away. +1 for steel outer surface. Cheers, Bennie.