I have never understood the gearbox/primary chain...

Ok, this doesn't really matter but I've never figured out one thing about the design of these bikes.

The gearbox can pivot fore/aft to adjust the primary chain tension (pre Mark III). Fine - don't have a problem so far. BUT, although the gearbox can move, the primary chain case does not. So how the heck does that work? Yeah, I know it does but is it simply because the hole in the inside chain case is large enough to accomodate the range of possible adjustment? Doesn't really look like it but I guess it does. And that little felt washer...??? Same thing? It can actually accomodate whatever fore/aft adjustment and still prevent any oozing from the primary case? Again, I guess it does since mine has never leaked at all from there.

Admittedly there shouldn't be much oil there anyway but I'd think some would get splashed around up there - heck, what's lubricating the large bearing in the back of the clutch gear? Is it supposed to be splash lubricated or packed with grease?

LOL, this is another one of those things that I never worried about at all on my 71 Commando...just rode it!

There's a tack-welded "sandwich" of two oversized metal plates with lips that hold the felt washer in place. The plate assembly is then free to slide fore and aft in the oblong iner primary hole, and keeps MOST of the oil residue IN, and MOST of the road grime and moisture OUT. Later models have a cup inside, besides the felt washer, that excludes oil drippage, for the most part.

AHA! I have the chaincase out of my bike but didn't realize that portion with the felt washer can actually move. Now it makes sense. I guess those Wolverhampton guys weren't as crazy as I thought!

Those guys at Wolverhampton were crazy.

Where can I get the cupped inside washer for the inner primary seal, if you want to call it that. I am trying to stop all the oil I can out of the Primary.

Dave
69S

old britts as well as many other suppliers carry them. the new one will be fatter and a real trick stuffing into it's home. i was pushing a new one in and the housing shifted on me. for a moment i thought i had really butchered it but then the light came on. you'll prolly have to use a blunt screwdriver to persuade it over the mainshaft when you install it. squirt some light oil on it also.

Maybe need some clarifcation on the "cupped washer" here. The cup is not an add on part. It is a integral part of the inside sliding plate that is spot welded to the outer plate sandwhiched between the inner primary case. You need to remove the inner primary and drill out the spot welds in order to seperate the plates. Then to add the cupped inner, you must centralise the inner with the outer with a mandrel. Then either re-spot weld or drill and pop rivet. Prior to that, fit a new felt seal before putting the plates together. Oh, and again, there is no factory parts number for this cupped plate.

OK, now if you just need to replace the felt seal as is in whatever plates you have in the inner primary, the trick is to soak the felt seal in light oil, then squish it flat in a bench vise. Then it is more easily fitted into the circular recess between the plates, and it will gradually resume its shape and of course within a week, permit chain oil to dribble down the back.

Mick

I took those sliding plates apart (for the life of me I no longer remember why or how) and rather than spotwelding them together again, I inserted six of the tiniest little bolt/washer/nut combinations you ever saw (thanks again to Matt Rambow for that tip). Works great, eliminates having to find a welder, and of course allows the felt piece to be inserted before tightening up the bolts.

I'd MUCH rather use pop rivets than screws and nuts that can come adrift and thrash around in the primary case, possibly lodging in the alternator gap...

Greetings,
The last time I installed those plates I used my MIG welder to spot them. Just drill 4 radially spaced holes around the contact area about 1/8--3/16 inch (only in one plate). Hold them together (clamp) and give it one little zap in the middle of each hole, presto all done.

GB

PS. After I converted to primary belt I removed the plates to get a little ventilation, seems to work fine.

rgrigutis said:

old britts as well as many other suppliers carry them.

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Which other suppliers carry these later, 'cupped' inner seal plates?

If I search on the Old Britts site, which model year do I search in? I saw another thread on this cupped inner plate recently, but can't find it. If anyone can locate this thread, could they post it, please?

I'm guessing that if you spec '74, you'll get the right one...

Looks like item 2 - 060769 here (http://www.oldbritts.com/1973_g10.html) would be the right piece, they are only about $3, so I think it may be worth a try. Then again, it is the same part number on the 71. I checked out the 75 and there is a real oil seal for the trans to primary, but I guess they can get away with that because of the hydraulic tensioner.

My 69-70 spares list doesn't even mention it except for the felt washer.

I need a few other things, so I'll call Ella and see if it actually is different than my original flat one. Report later.

Dave
69S

My 73 chaincase looks just like that per the catalog and there has never been any leakage from there at all. So it works fine... (Is there an avatar for "fingers crossed?")

DogT said:

Looks like item 2 - 060769 here (http://www.oldbritts.com/1973_g10.html) would be the right piece, they are only about $3, so I think it may be worth a try. Then again, it is the same part number on the 71. I checked out the 75 and there is a real oil seal for the trans to primary, but I guess they can get away with that because of the hydraulic tensioner.

My 69-70 spares list doesn't even mention it except for the felt washer.

I need a few other things, so I'll call Ella and see if it actually is different than my original flat one. Report later.

Dave
69S

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Great, thanks Dave, look forward to that.

grandpaul said:

I'd MUCH rather use pop rivets than screws and nuts that can come adrift and thrash around in the primary case, possibly lodging in the alternator gap...

Click to expand...

I see your point but I didn't have access to a welder, Mr. Rambow himself suggested it, and I tightened the bolts thoroughly with a bit of blue loctite. Used stainless parts so at least they won't be magnetically attracted to the rotor if they do come loose - obviously, I still wouldn't like to see them bouncing around in the primary case.

Was in there recently to get the gearbox out and all is holding up so far....