Primary seal on a '72 Commando

I've replaced the alternator wire grommet and the felt seal for the gearbox shaft. Still getting oil drips at the bottom of the primary case. Think it may be time to replace the big rubber band. It lasted 15 years. What's the normal expected life? This is one of those long term maitenance items, so I'm not sure.

illf8ed said:

I've replaced the alternator wire grommet and the felt seal for the gearbox shaft. Still getting oil drips at the bottom of the primary case. Think it may be time to replace the big rubber band. It lasted 15 years. What's the normal expected life? This is one of those long term maitenance items, so I'm not sure.

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Try a new gasket and go easy on tightening the outer cover, if it's pre MKIII. Some put a slather of silicone along the bottom. I've used brake clean to clean the surfaces prior to the silicone.

Make sure your inner is properly shimmed. This above all will keep the primary seal up tight.

RTV on center bolt, wire grommet, big o-ring, sheet metal halves for felt seal keeps me sealed well. Be sure to clean with solvent first.

no real need to order from a brit supply place when all you need is three feet of 1/4 inch tubing,
I get it at AutoZone, etc

I pretty much RTV'd mine into the inner groove and put a thin skim coat on the outer when installing. 25ft-lbs on the center bolt. Like others have said, make sure the inner is shimmed right and is flat.

But then all oil finds itself to the bottom of the primary for some reason, not only because it's the lowest point.

Mine hasn't leaked for about 3 years now, a new record.

Dave
69S

illf8ed said:

I've replaced the alternator wire grommet and the felt seal for the gearbox shaft. Still getting oil drips at the bottom of the primary case. Think it may be time to replace the big rubber band. It lasted 15 years. What's the normal expected life? This is one of those long term maitenance items, so I'm not sure.

Click to expand...

I don't know if you can put a figure on how long they should last, but if you've taken one out and tried to use it over it might not work too well. Over time they go from an O-ring to a D-ring with the flat side facing the outer cover. It's pretty much impossible to get it oriented the way it was originally when you put it back, add to that the rubber hardens over time so it might not seal as well as new. Adding an RTV sealer to the grove helps when you fit a new O-ring. It helps it seal on the rough surface of the bottom of the groove and it helps keep it in the grove when you remove the cover, so you can use it over.

Before you put the O-ring in try bolting the covers together, you can see if they are warped from DPO's overtightening the nut. It's an O-ring not a gasket, sheesh. If you're lucky, they machined your covers so that they bottom out before they contact around the sealing surface. If not, you can shim it.