Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Nexus-8 Drive-side Seal Question

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Nexus-8 Drive-side Seal Question

Old 11-24-22, 12:29 PM
  #1  
sweeks
Senior Member
Thread Starter
 
sweeks's Avatar
 
Join Date: Sep 2004
Location: Chicago area
Posts: 2,541

Bikes: Airborne "Carpe Diem", Motobecane "Mirage", Trek 6000, Strida 2, Dahon "Helios XL", Dahon "Mu XL", Tern "Verge S11i"

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 978 Post(s)
Liked 574 Times in 395 Posts
Nexus-8 Drive-side Seal Question

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!
sweeks is offline  
Old 11-24-22, 02:18 PM
  #2  
maddog34
Senior Member
 
maddog34's Avatar
 
Join Date: Jul 2015
Location: NW Oregon
Posts: 2,974

Bikes: !982 Trek 930R Custom, Diamondback ascent with SERIOUS updates, Fuji Team Pro CF and a '09 Comencal Meta 5.5

Mentioned: 15 Post(s)
Tagged: 1 Thread(s)
Quoted: 1299 Post(s)
Liked 739 Times in 534 Posts
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.
maddog34 is offline  
Old 11-24-22, 06:05 PM
  #3  
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 8,108
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 937 Post(s)
Liked 652 Times in 367 Posts
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.
Dan Burkhart is online now  
Old 11-24-22, 09:24 PM
  #4  
sweeks
Senior Member
Thread Starter
 
sweeks's Avatar
 
Join Date: Sep 2004
Location: Chicago area
Posts: 2,541

Bikes: Airborne "Carpe Diem", Motobecane "Mirage", Trek 6000, Strida 2, Dahon "Helios XL", Dahon "Mu XL", Tern "Verge S11i"

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 978 Post(s)
Liked 574 Times in 395 Posts
Originally Posted by Dan Burkhart
Is this a hub that you have converted to oil bath lubrication?
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!

Last edited by sweeks; 11-25-22 at 10:19 AM.
sweeks is offline  
Old 11-26-22, 10:29 AM
  #5  
tcs
Palmer
 
tcs's Avatar
 
Join Date: Mar 2007
Location: Parts Unknown
Posts: 8,580

Bikes: Mike Melton custom, 1982 Stumpjumper, Alex Moulton AM, 2010 Dawes Briercliffe, 2017 Dahon Curl i8, 2021 Motobecane Turino 1x12

Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 1645 Post(s)
Liked 1,785 Times in 1,041 Posts
Shiver me timbers! Y-34R 98110 seems to be available as a spare part.
tcs is offline  
Likes For tcs:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.