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servicing shimano dynohub bearings

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servicing shimano dynohub bearings

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Old 11-04-09, 10:46 PM
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JimBeans83
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servicing shimano dynohub bearings

Am considering one from the 3n7x (eg 3n71) series, they have been described as Ultegra level hubs, and I've read many posts from satisfied people with 5,000+ miles.

But - looking at the exploded diagram, there is only one side for the bearings. Am I missing something? Is the other side hidden with the dynamo internals (and unserviceable, ala Shimano freehub bodies)?

Same rules for adjusting these bearings as with non-dyno hubs - eliminate the play under the compression of the quick release?

http://bike.shimano.com.sg/media/tec...9830648089.pdf
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Old 11-04-09, 11:17 PM
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Other activity elsewhere on same topic,

http://groups.google.com/group/rec.b...3117c16c4e4f6c
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Old 11-05-09, 11:46 AM
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unterhausen
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Thanks for asking this question, I better overhaul mine.
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Old 11-05-09, 12:40 PM
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Originally Posted by unterhausen View Post
Thanks for asking this question, I better overhaul mine.
My advice is don't do it unless you are sure that there are bearing troubles. Or at least, just inspect the easy non-rotor side first to see if there any reason to believe it is worth the risk and trouble of taking the rotor apart.


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Old 11-05-09, 01:00 PM
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Originally Posted by JimBeans83 View Post
Am considering one from the 3n7x (eg 3n71) series, they have been described as Ultegra level hubs, and I've read many posts from satisfied people with 5,000+ miles.

But - looking at the exploded diagram, there is only one side for the bearings. Am I missing something? Is the other side hidden with the dynamo internals (and unserviceable, ala Shimano freehub bodies)?

Same rules for adjusting these bearings as with non-dyno hubs - eliminate the play under the compression of the quick release?

http://bike.shimano.com.sg/media/tec...9830648089.pdf
No you aren't missing anything. According to Shimano the rotor side bearings aren't meant to be serviceable. In case of trouble you replace the entire rotor part (part no. 3 in the pdf).

It can however be done, but look at the google.group thread on why it should be avoided.

German www.rose.de has the DH-3N72 (36H) on a serious sale at the moment for only 28 euros:
https://www.roseversand.de/output/co...&detail2=24399
Or the T-660 (32H) for 30 euros:
https://www.roseversand.de/output/co...&detail2=16595

I just bought two DH-3N72

All the Shimano generator hubs are regular cup-and-cone designs, and they are adjusted like any other Shimano hub. It is however slightly more difficult to do since the magnet resistance makes the "feel" different. So get some feel for how the hub rotate before taking it apart.

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Old 11-05-09, 01:26 PM
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got excited a bit there....dynohubs are exclusively sturmey archers...and even thow its not recomended i opened mine up and serviced the bearings, just because im that kind of crazy guy..
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Old 11-05-09, 01:32 PM
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It sounds like just robbing the internals from another hub is cheaper than trying to replace that part, as you've pointed out with promotional pricing. Much like robbing the freehub body from another shimano hub instead of buying the freehub part itself. €28 is a great price. 30 euros every 2 years or so to refresh the hub isn´t too big of a problem. Cheaper than replacing the whole wheelset. Hard to add up the money to arrive at the SON pricing this way.
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Old 11-05-09, 02:01 PM
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I've got just over 4000 miles on mine and that included going through two Buffalo NY winters (I am a daily commuter). I have had no reason to even consider taking appart the front bearing. These units appear to be very well made and realy are zero maintenance. By the time it breaks I'll just upgrade to a new and improved model. That will hopefully not be for a few more years. I figure there is no reason I can't get 10,000 miles out of the generator hub.

Happy riding,
André
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Old 11-05-09, 03:14 PM
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Originally Posted by JimBeans83 View Post
It sounds like just robbing the internals from another hub is cheaper than trying to replace that part, as you've pointed out with promotional pricing. Much like robbing the freehub body from another shimano hub instead of buying the freehub part itself. €28 is a great price. 30 euros every 2 years or so to refresh the hub isn´t too big of a problem. Cheaper than replacing the whole wheelset. Hard to add up the money to arrive at the SON pricing this way.
The cones for the Shimano's generator hubs are usually cheap. On the Generator hubs I have serviced, (2/3N7x series) the "hidden" cone inside the rotor is identical to the non-rotor side. I assume that Shimano have designed their newer hubs the same way, so it should be cheap enough to replace the cones. The cups are allegedly made the same way as the Ultegra cups and super-polished with Borozon/Borazon (hard enough to scratch diamond), so they should last a very long time. The rotor part is very simple without any moving parts and is more and less impossible to damage or wear out. The Shimano sportsdynamo hubs have good sealing too, so the problems should be few and perhaps limited to new cones.

Both the Shimano and SON hubs are difficult to service because of the rotor wire. In case of Shimano, the wire runs along a slot in the axle out to the connector. To service a DH-3N7x hub you need to follow certain steps in order to avoid breaking this wire. Tirinity bicycles used to have such a guide, but their website is now gone. I probably should make another guide, but I really lack the time for the moment..

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