Bicycle Mechanics - Dust Cap/Seal?

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Makeitso
11-05-06, 08:06 PM
I have a 89-90 vintage GT Timberline MTB and on the rear non-driveside axle, there is some kind of a seal or dust cap.
It is a Shimano, the hub says FH-HG20. The seal says Shimano Japan and VIA.

What I want to know is:

1. What is it? I guess the question would be is it an actual seal or just a dust cap?
2. Is it supposed to be all metal or is it supposed to actually have a neoprene lip or some othe postive seal surface.
3. Where can I get a new one at and is the one on the drive side the same?
The ones on the front hub appear to be the same as the one I have off, I can't really see the one behind the freehub.

mechBgon
11-05-06, 08:13 PM
On an HG20 hub, it's a metal dust shield. The cone may have a couple of plastic split-ring seals in a recess, like piston rings in an engine, that sit in the opening of the metal dust shield to form a basic seal, but I can't recall if HG20's have those.

The one on the driveside is different. If you toasted the non-driveside dust shield, the best source for a new one is another HG20 hub. They're easy to deform, so you have to remove them very carefully using a minimum of force. My favorite method is a Cal-Van slidehammer bearing puller and lots of patient ginger tink-tink-rotate, tink-tink-rotate action.
Makeitso
11-05-06, 08:33 PM
I think it's OK to use, it just has some damage where an LBS along the line damaged it.
It has some tool marks on it but seems to be usable, I would like to find one if I can and replace it.

Where can I find a hub to get one from? Do you know of a place?

mechBgon
11-05-06, 09:56 PM
I think it's OK to use, it just has some damage where an LBS along the line damaged it.
It has some tool marks on it but seems to be usable, I would like to find one if I can and replace it.

Where can I find a hub to get one from? Do you know of a place?Hit your local bike shop. They may have a bin of hubs or hubshells that include the kind you need a dustcap from :) If I see one heading for the trash where I work, I'll scavenge the dustcap and drop you a PM to see if you still need one. Since it's the beginning of winter, business is very slow, so don't hold your breath :)