Shimano DH-3N30 dyno-hub - Any Good?

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bivvy
Posts: 5
Joined: 18 Jul 2015, 5:55pm

Re: Shimano DH-3N30 dyno-hub - Any Good?

Post by bivvy »

That's all good to hear. Did you manage to re-grease both sides? I have heard that it may damage the dynamo generator if not done carefully in a certain way. If so, did you happen to find any suitable guidelines that may be online?

These hubs would need to be re-greased more often compared to the likes of the 72 which (I read) has dura ace level sealing with labyrinth ! But if it's no harder than my deore hubs to service then that won't be so much of a problem!

PS. I do wonder from what you have found re: resistance, that a lot of these cheaper hubs are not set with the correct bearing tension from the factory. And this is why some people in the reviews say they notice drag. But some may be some sensitive than others too I guess !
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CREPELLO
Posts: 5559
Joined: 29 Nov 2008, 12:55am

Re: Shimano DH-3N30 dyno-hub - Any Good?

Post by CREPELLO »

I must admit, it was only the one side regreased.

Good point about bearing adjustment being out on some users hubs. It is fairly easy to get the right adjustment. It's a case of getting the hub to rock back and forth between two magnetic poles, as many times as possible. Well adjusted, the hub will rock freely many times. Obviously, at the other end, you're still trying to remove free play, like any other hub, so it's a balance between the two.
Brucey
Posts: 44516
Joined: 4 Jan 2012, 6:25pm

Re: Shimano DH-3N30 dyno-hub - Any Good?

Post by Brucey »

if you increment the bearing adjustment tighter (by a tiny fraction of a turn, checking each time with the QR and/or locknut tight against the cone) until the free play is gone, that is the correct adjustment. Drag in the hub is very misleading by comparison, and will vary between hubs or with the same hub depending on seal drag/wear. Obviously (like any other QR hub) if there is no free play with the QR half-tight, the bearing adjustment is too tight.

WIth most shimano hub generators if you slacken the LH cone off you can draw the axle to the right far enough that there is a gap in the seal assy. If you simply add more (good quality) grease through this gap (and adjust the bearings correctly) the life of the hub can be greatly extended. There is a risk, which is that if the balls become dislodged, they can sit on the edge of the bearing cup and this will make the hub impossible to adjust and it will eat itself unless you prod the balls back into position. I have found that the pickup tube from inside an aerosol is squashy enough that it can go through the gap in the seals; used with a nozzle type grease gun you can get plenty of fresh lube (with decent corrosion inhibitors in it, unlike the shimano stuff) into the bearings.

cheers
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rofan
Posts: 142
Joined: 8 Jul 2012, 6:29pm

Re: Shimano DH-3N30 dyno-hub - Any Good?

Post by rofan »

pete75 wrote:I bought one of these but what they actually sent was a 3N31 as well, a little strange as they're advertising the 3N31 at twice the price of the 3N30. No idea what the difference is.

weight (diff. 100g) Winding copper <-> aluminium(N31)
pete75
Posts: 16370
Joined: 24 Jul 2007, 2:37pm

Re: Shimano DH-3N30 dyno-hub - Any Good?

Post by pete75 »

Brucey wrote:if you increment the bearing adjustment tighter (by a tiny fraction of a turn, checking each time with the QR and/or locknut tight against the cone) until the free play is gone, that is the correct adjustment. Drag in the hub is very misleading by comparison, and will vary between hubs or with the same hub depending on seal drag/wear. Obviously (like any other QR hub) if there is no free play with the QR half-tight, the bearing adjustment is too tight.



cheers


Another way is to make up the simple tool shown here http://www.sheldonbrown.com/cone-adjustment.html just scroll down to "Special tool for rapid cone adjustment under load"
'Give me my bike, a bit of sunshine - and a stop-off for a lunchtime pint - and I'm a happy man.' - Reg Baker
Brucey
Posts: 44516
Joined: 4 Jan 2012, 6:25pm

Re: Shimano DH-3N30 dyno-hub - Any Good?

Post by Brucey »

I have a tool like that (actually, mine's better) which is perfect for regular use.

But for occasional use, you can use a few M10 washers in place of the dropouts, and it works well enough.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
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