How to install oil seal disc and felt seal in inner primary? (2008)

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Jun 14, 2007
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Can anyone advise how this is done? - I don't get it.

My old discs, with the felt seal between them, were damaged but it took some doing to get them out - they were like a single unit, fused together, so I had to bend one side back until it was small enough to fit through the hole in the inner primary cover.

The new ones are two identical looking aluminum discs, plus the felt seal. Is it just the clamping force of the gear box and clutch basket against the two discs (one on each side of the inner primary cover) that forces them together and "fuses" them as the old ones were?

Any advice appreciated - a long ways to go to get the primary back together and this has me stymied.

Thanks folks - BrianK
I reckon a lot of people will have some tips for DIY for this job. But to answer your question, the plates are placed either side of the inner primary, held in a jig and spot welded.
Ouch. That's not DIY for me....thanks Capt; hope others have other methods but that rings true...
Brian, Take the inner case with the two discs down to your local car-body shop and they will be able to spot weld the two discs together in about 30 seconds, worth a six pack of beer I reckon. Just make sure that the centre holes of the two discs are lined up. In order to fit a new felt seal to the centre of the sliding discs I put oil on it and compress it in a vice between two steel plates. It generally remains squashed long enough to fit it into the slot and then slowly expands.

If, in fact, your new discs are aluminum, you may not be able to spot weld them together at your local body shop. Chances are they are steel?
Just had this done on my 850 chaincase. The discs are steel with some sort of plating, probably zinc. My old ones were thoroughly rusted.

My machinist made a fixture to clamp them together and hold them in the proper alignment while he spot welded them. The originals were spot welded in four places at the factory. An easier way to remove the discs is to drill out the spot welds and separate them.

The felt seal is a PITA, but soaking in oil and some careful work with a dental pick and small screwdriver enabled me to get the new one in. Squishing it in a vise is a good idea. I wish I'd thought of that!

I did buy a spare. I could flip the old one out, squish the new one in the vise, and see for myself how much easier that makes the job. On second thought, maybe I'll take Dave's word for it! :lol:

I'll check tonight, but mine felt like aluminum. I'll take a magnet to 'em when I get home.

Would something like JB Weld work if they are?

Not quite understanding the issue with the seal. It's thick, but doesn't seem to be a problem to fit into the space provided for it....?
Well, it's steel (ferrous/magnetic anyway).

I'll wander over to the local welding shop this weekend.

In the meantime, I've got the felt seal in between the discs and a bunch of iron barbell discs sitting on top of it. A poor man's vise.
Debbie, I'm delighted you put so much trust in me. I must confess that I've been through the usual pallaver with the dental pick and screwdriver numerous times before my eureka moment. Why waste the other seal? You could use it to form the basis of a new project!

dave M said:
Why waste the other seal? You could use it to form the basis of a new project!


:lol: That's pretty much how this 850 project got started!

I'm still not understanding how getting the seal in is so difficult. The two metal pieces are separate, and the seal fits easily into the groove provided. Then the thing (I now know) gets fitted to the inner primary cover, one metal piece inside and one outside, and spot-welded.

I'm worried I'm missing something...?
Oh I get it. You are just talking about replacing the felt seal WITHOUT separating the discs.... DOI! Never mind....

It's pretty tuff to clamp the two discs over the inner primary with the felt inside, get everything aligned, then spot weld. The last time we made a dowel to fit in the hole and align the discs, then two clamps and spot weld. I stuffed in the felt with two tiny flat blad screwdrivers afterward.
Thanks. I can see my local welding shop having little interest in this project! Are there alternatives to spot welding - JB Weld or the like?
Are there alternatives to spot welding

I don't see why you couldn't drill and rivet. Just make sure your rivets are short enough and placed where the tranny sprocket and clutch basket will clear. Classic "pop" rivets may not clear, I would look to the peen-type.

Small machine screw and nuts might do it also. Just use loctite on the threads.

I don't think epoxy (JB Weld) would do the job here.
felt seal

Brian,if riveting is not successful,you can ship the plates to me and I can spot weld for you I'm in Ohio, just East of Cleveland.PM me and I will give you my home address.
A very kind offer, James, thank you. Unfortunately, the welding has to be done while the plates are held on either side of the inner primary cover so I'd need to ship you the whole thing.

Let me see if I can muddle through - I may yet take you up on your offer. Thanks again (and to all) - Brian
Brian, If you do the preparation yourself ie. make sure that the parts are clean and that you have some kind of locating dowel to centre the holes on the plates, it really is a job of less than 5 minutes, including setting up and switching on the machine. It can be done by anybody with a spot welder. I suggest you don't go to the sales department of your body shop, just talk to the foreman nicely, offer a box of beer for the guys and your job will be done. Any metal fabrication shop should also have the equipment and it doesn't need a 90 year-old guy with a lifetime of skill and experience. Most working chaps are interested in old vehicles and delighted to help.
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