sweeks

I'm servicing a Nexus 8-speed hub and noticed that the seal installed in the right-side dust cover (item #30 in the parts list) is much too small to stay in place. The seal has a metallic ring included, so I can't see how it could have shrunk.
Is there any reason not to simply seal it in place with some RTV silicone?
Thanks for any suggestions.
Steve

The seal literally falls out of the dust cover.



The gap is visible between the seal and the dust cover. I believe this was supposed to be a press fit.


Part #30... looks like the seal is integral.


Happy Thanksgiving!

maddog34

it's not just a seal.. Quit second guessing the engineers and reassemble your hub with a dab of light hub grease... They're listed as a set because if one is bad, both pieces need replaced. the Dust cover requires Rigidity.. the Seal requires flexibility... Plastic of the nature of that dust cover is rather oily... the two can not be made as "one piece."

Now.. COMPRESS the seal as it will be once the Sprocket/snap ring are installed....... what happens? i bet it SEALS against the vertical surfaces it mates to, and possibly the outer diameter of another hub piece...... the dust cover is then allowed to float somewhat, reducing friction.

just a guess.

other parts i've seen sold as pairs... thrust washers and bearings... points and condensors... oil filters and sealing rings... banjo bolts and sealing washers... fuel filters and those annoying little squeeze bands... wrist pins and tiny circlips that can fly farther than most airliners..... etc.

Dan Burkhart 

Is this a hub that you have converted to oil bath lubrication? I noticed over time that an Alfine hub that I converted to ATF showed a softening of the plastic cap. Could be what is going on here.

sweeks

Thanks, Dan,
I was hoping to hear from you. Yes, I have been lubricating this hub with gear oil for many years. The gear cluster is dipped and allowed to drain for a while before reassembly. The seal can't have shrunk because it has a metal ring in it. The plastic dust cap is hard plastic, and I think if it had expanded, it wouldn't fit in the hub shell (it does). What would be the harm in using some silicone seal to hold the seal in place? I'd center the seal in the hole.

Edit: the difference between the seal OD and the dust cap ID is 0.9mm... if anyone cares!

tcs

Shiver me timbers! Y-34R 98110 seems to be available as a spare part.