Uh oh, slipping hub

[NLCTVWguy]

OK folks, it's not too terribly often I come across a technical problem that stumps me, since like a lot of you I have the "gearhead" gene... but for this one I need some help, or at least encouraging words.

I was riding this Dyno 4-speed Moto-Glide, and trying to take off quick, a lot of force on the pedals, and the hub seemed to go CRUNCH like something let go in it. Now, with any significant amount of torque, the hub slips. It feels rubbery, like a slipping clutch. At low amounts of force, the bike can be ridden. The shifter still works, and works smoothly. But something's broke...

The hub does not make any kind of clicking, grinding, or vibration as it spins. Everything seems normal until you apply torque to it.

I cannot find a service diagram for this beast. It's an internal drum brake, and Shimano 4-speed internal laced up to a 24" rim, standard issue hub for a mid-90's Dyno. Apparently it's obsolete? I can't find much info at all about them. Even Sheldon Brown doesn't offer much about these.

Any ideas will be appreciated... including "toss it and build a Nexus 7"...

--Rob

 

[rick74304]

Hey Rob, have you checked here? http://techdocs.shimano.com/techdocs/index.jsp
Hope that helps
Rick

 

[deorman]

Sounds as if it has a coaster style drive cone, and either it or the area of the hub it engages is damaged. I could be way off, just a guess.

 

[2manybikes]

I have a nexus 7 that has the same problem. Were the anti-rotation washers in place when your hub made the "crunch"?
My hub spun in the dropouts a little bit under heavy load and now it acts just like yours.

I will be looking forward to seeing if you can find a fix.

 

[NLCTVWguy]

Hey Rick-

Thanks, that link is awesome. Hopefully I find some answers there.
It may end up just being an adjustment issue but I am not sure yet.
Supposedly it's "done it before"... hmm we will see.

--Rob

Hey Rob, have you checked here? http://techdocs.shimano.com/techdocs/index.jsp
Hope that helps
Rick

 

[user 135]

I had a coaster hub wind up tighter than a top when the brake arm came undone. It was slipping like crazy and non functioning. I was sure the internals were shot. I readjusted the bearing cones and locknut and it cured the slipping.