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

Nexus Inter-8 IGH Coasting Fault

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 Inter-8 IGH Coasting Fault

Reply

Old 02-16-19, 10:32 PM
  #1  
paulb_in_bkln
Senior Member
Thread Starter
 
Join Date: Mar 2018
Location: Brooklyn, NY
Posts: 389

Bikes: 1983 Trek 600, 1972 Raleigh Sports Step Thru, 2007 Dahon MuP8, Dahon Speed, Public IGH

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 204 Post(s)
Nexus Inter-8 IGH Coasting Fault

Last year I came across a website that panicked me into deciding to open, clean, and relube my five-year-old Nexus Inter-8. It had pictures of hubs with horrible internal damage caused by careless owners. So I watched videos and bought a tube of Shimano's runny white grease and opened the hub and actually it was just fine. There was plenty of grease, no dirt, no rust, no contamination, no damage. But I removed the circlip/snap ring, separated the two halves, cleaned it all off, regreased, and then re-assembled it. But for my problems with the old cable housing and the improperly installed (by a bike shop) new cable described in another thread, the hub seemed to be working fine. Basically it works just like it did before. EXCEPT: there's a lot of drag now when the hub is coasting, that is, dragging the pedals around. It's slight in first gear and then gets more pronounced with each higher gear. In 8th gear the pedals get carried around firmly enough to give one quite a whack. Did I overtighten one of the bearings? I don't feel like I did. Could there be another cause?
paulb_in_bkln is offline  
Reply With Quote
Old 02-17-19, 07:02 AM
  #2  
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 7,176
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 482 Post(s)
Originally Posted by paulb_in_bkln View Post
Last year I came across a website that panicked me into deciding to open, clean, and relube my five-year-old Nexus Inter-8. It had pictures of hubs with horrible internal damage caused by careless owners. So I watched videos and bought a tube of Shimano's runny white grease and opened the hub and actually it was just fine. There was plenty of grease, no dirt, no rust, no contamination, no damage. But I removed the circlip/snap ring, separated the two halves, cleaned it all off, regreased, and then re-assembled it. But for my problems with the old cable housing and the improperly installed (by a bike shop) new cable described in another thread, the hub seemed to be working fine. Basically it works just like it did before. EXCEPT: there's a lot of drag now when the hub is coasting, that is, dragging the pedals around. It's slight in first gear and then gets more pronounced with each higher gear. In 8th gear the pedals get carried around firmly enough to give one quite a whack. Did I overtighten one of the bearings? I don't feel like I did. Could there be another cause?
Sounds more like friction between the cog and dust cover.While it's possible to remove the internals with the cog still on the driver, it's better to remove it so you can ensure everything is fully snapped into place when you're putting it back together. An improperly seated dust cover can cause exactly what you describe.
Dan Burkhart is offline  
Reply With Quote
Old 02-17-19, 08:29 AM
  #3  
paulb_in_bkln
Senior Member
Thread Starter
 
Join Date: Mar 2018
Location: Brooklyn, NY
Posts: 389

Bikes: 1983 Trek 600, 1972 Raleigh Sports Step Thru, 2007 Dahon MuP8, Dahon Speed, Public IGH

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 204 Post(s)
Originally Posted by Dan Burkhart View Post
Sounds more like friction between the cog and dust cover.While it's possible to remove the internals with the cog still on the driver, it's better to remove it so you can ensure everything is fully snapped into place when you're putting it back together. An improperly seated dust cover can cause exactly what you describe.
Thanks! I will check it again. It seemed like I had it seated correctly, but maybe not.
paulb_in_bkln is offline  
Reply With Quote
Old 02-17-19, 11:38 AM
  #4  
paulb_in_bkln
Senior Member
Thread Starter
 
Join Date: Mar 2018
Location: Brooklyn, NY
Posts: 389

Bikes: 1983 Trek 600, 1972 Raleigh Sports Step Thru, 2007 Dahon MuP8, Dahon Speed, Public IGH

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 204 Post(s)
I think you're right that the dust cap is not seating properly. Is that visible in the photo? But that's the best I can do. I just removed everything, sprocket included (yet again). The hub internals seem (I say, "seem") fully seated in the hub shell. But the cap will not go down any further, even with some tapping from a hammer. When I re-joined the two sections of the hub's internals, could I somehow not have fully seated those? But the circlip is in place. If the two halves weren't perfectly joined, would the gears work at all? Incidentally, the dust cap has its own removable seal which has a flat side and a grooved side. I've lost track which side should face where. Anyone remember? Hard to tell from Shimano's PDF but it looks as if the groove is supposed to face in toward the hub. Not sure, though.
paulb_in_bkln is offline  
Reply With Quote
Old 02-17-19, 08:43 PM
  #5  
sweeks
Senior Member
 
sweeks's Avatar
 
Join Date: Sep 2004
Location: Chicago area
Posts: 1,120

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

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 479 Post(s)
Originally Posted by paulb_in_bkln View Post
Incidentally, the dust cap has its own removable seal which has a flat side and a grooved side. I've lost track which side should face where. Anyone remember? Hard to tell from Shimano's PDF but it looks as if the groove is supposed to face in toward the hub. Not sure, though.
It's been a couple years since I had mine apart, but I believe you're right.
sweeks is online now  
Reply With Quote
Old 02-21-19, 09:01 AM
  #6  
paulb_in_bkln
Senior Member
Thread Starter
 
Join Date: Mar 2018
Location: Brooklyn, NY
Posts: 389

Bikes: 1983 Trek 600, 1972 Raleigh Sports Step Thru, 2007 Dahon MuP8, Dahon Speed, Public IGH

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 204 Post(s)
Almost ready to drop this thing in the Hudson River. (I won't really do that.) I did discover my own bonehead error; when I re-joined the two halves of the hub mechanism I reversed the big bearing retainer. I've corrected that. Experimentally, I put the hub together without the dust cover and put it on the bike. That seemed to eradicate the noise and coasting friction. But with the cover on, it's still there, though I think less than when the bearing retainer was on wrong. (That is not surprising.) I guess the last resort is to bring the thing to a Shimano Service Center and ask them to go over my work and find out what, if anything, I've done incorrectly. Picture shows my error. Part #7 , I had it reversed.
paulb_in_bkln is offline  
Reply With Quote

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