Servicing Shimano dynohub bearings
Servicing Shimano dynohub bearings


In this video we are going to attempt to service the output side bearings of a Shimano dyno hub. In the last video I removed the internals from the hub shell I’ll provide a link to that video here if you look at the top of your screen you’ll see a link to that video now. A little bit of the back story of this hub, it was sent to me by a gentleman who had said that it had stopped producing electricity and so he sent it to me to do some failure analysis. When I took it out of the package, it actually did work. I hooked a light up to it and tested it first with a multimeter and then with a light and it was producing full voltage. I will insert a video clip here that shows that test . Ok, I have it rigged up here to give it a little test. I have a Herrman’s dyno light hooked up to it with a set of alligator clips because I do not have a proper clip for it. and I’ve wound the string around the hub. If you’re old like me you’ll remember winding up your starter on your lawn mower before they had the recoil start, so that’s kind of what I’ve done here. So we’ll give it a pull and we’ll see if it generates some power. Well, look at that. It’s doing pretty good good for a hub that wasn’t working. So, you saw it functioning there so anyway carrying on here we’re now going to attempt to service the the power output side bearings as I said before. Now, Shimano tells me, because I talked directly to them, I actually called their service techs, and what they told me was that this hub is not, in their words, it is not maintainable but they said that the the bearings on the the non output side are serviceable it’s just a regular cup and cone bearing, loose ball, but their claim is that the power output side is not serviceable and so once the bearings are shot on that side, what you’re supposed to do is just buy a new internal assembly and remove the old one as I demonstrated in that previous video and insert the new one and there you go So anyway today what we’re going to do is we’re going to attempt to access this bearing and see whether we can in fact service it. No manual exists for this this will be a voyage of discovery and I’ve not done it before so you’ll be going on this voyage of discovery with me and we’ll see how we make out. So the first thing we need to do is remove this lock nut. 17 millimeter wrench flats It’s not on there very tight, And then the connection box I’m assuming there is going to be a wire there. Ok so I see one wire looks to be a single lead and this connector has no wire leading to it so it appears that the axle is actually the power path for one side and this lead goes to this other connector. So what we’ve got here is some five-sided nuts. It appears that they’re shaped that way to mate with this hole to keep this oriented in the correct direction and there’s a little tongue there so I guess it’s not going to unscrew it’s going to lift right off well there’s actually two of them. We will keep these in the order that they came off Let’s see what we got now. Alright so we got a little groove there that wire can fit through but to get these parts off this will have to come out of the way so I’m guessing that that connector is probably going to have to come out of there. Alright so if we fit that wire into that groove we can get the rest of these parts out of the way. it looks like a bunch of insulating material around there so we have to put some electric liquid tape around there later so let’s see this turns in relation to the axle and it’s actually unthreading, that’s a good sign. And with that wire tucked into that slot in the axle we should be able to get that up and out of the way and we’ll see what’s underneath there. It looks like the cone is actually integrated with that cap It’s pressed in there. So what we have here, looks like a little rubber seal and it looks like its directional cause it’s kinda cone-shaped so we’ll keep that facing up and look at this. We got loose ball bearings and we can lift it right off of there. Who says you can’t service these things? It appears that there’s not really a lot to go wrong with this thing other than the possibility of connections getting burnt or whatever and the other possibility is that this wire, it is insulated, if the insulation was to wear through then where it contacts the axle,it could create a short other than that there’s not a heck of a lot lot to go wrong with us as I can see it So inspection of the cups and cones shows that there is no wear everything looks good so we will re assemble. Alright so I’m not going to go into long boring detail on reassembling the cup and cone bearings. Plenty of other places online as you can find that Now it occurred to me a little too late that I should have measured how much axle was protruding before we unscrewed that because this does not bottom out. But in any case we can kind of estimate and go from there So now we put these parts back in place in the order they came off That wire was on top of that and then there’s a groove on the underside there that that fits into and then the second on top like so make sure nothing’s being pinched there and the lock nut That wiggle would be normal. After that’s threaded into the shell, the bearing adjustment will be made from the other side. So now the next step is to thread it into the shell. Alright so now we torque down the lock nut here. A 17 millimeter cone wrench will fit underneath the connection box although snuggly. This might have been one of the issues of why it didn’t work because the axle is one of the electrical conductors. The only thing that gives it a really good contact is the lock nut on this contact here so aside from the fact that locknuts should be properly torqued down. it also in this case provides for electrical connection. Now before we adjust the non output side bearing we want to make sure that the ring is tightly screwed in. So once again I’m going to put three spokes in it and clamp them in the vise. and this time rather than using the tool I’m just going to use a brass punch and just give it a few taps here to make sure its torqued in there properly. So all that’s left is to adjust the non output side. The cone flats take a 17 millimeter cone wrench, and it’s just a standard cup and cone adjustment procedure. Alright so it’s time to give it a spin test again with the light hooked up to see what we got. We have power. So, a couple of final thoughts here. I think that the reason that the owner experienced a failure of power conductivity was probably something to do with the locknut being loose because it requires a good contact here the bearings are easily serviceable I find. I don’t think that for Shimano to say that they’re not maintainable I really don’t think that that’s true I think it was quite easy to get in there and and services the bearings. all things considered. To do a bearing service did not require the removal of the internals that was you know just to service the bearings that’s an unnecessary step the only reason to remove the internals would be to actually replace them to swap in a new set but I mean in the interest of science we have to go ahead and do that anyway so anyhow yeah good as new. Very simple device there really isn’t a lot to go wrong, other than the possibility of fracturing the lead wire or having the insulation scuff off it or whatever but over all not that hard to service.

15 thoughts on “Servicing Shimano dynohub bearings”

  1. VSM Etc says:

    Great video showing how you trouble shoot these hubs. Thanks for your efforts and showing how to service the "unservicable" 👍🏼

  2. David Dedick says:

    Interesting video. Thanks!

  3. damian33dc says:

    can you please give a short review of the HERRMANS H-ONE light ?
    I just order one of amazon still in the mail ..

  4. BlockCylinder says:

    I love your channel, Mr. Burkhart. As one of the few mechanics in NYC willing and able to service gear hubs and dynamo hubs I've done most of the jobs in your videos; some I've done while using your video as a guide.

    Isn't it more likely that the reason your customer's lights stopped working has something to do with the exposed wires or the connections at the lights? Those parts are so much more fragile and prone to interference than the hub axle, etc.

  5. Steffen Stengård Villadsen says:

    what is the model number DH 2N??

  6. George Willoughby says:

    Superb Video Dan !!!! I've done approx 12,000 miles on my DH-3N30 … will probably service it now you have showed how …

  7. Gromitdog1 says:

    What is that clear grease you are using? Silicone grease?

  8. Hüseyin Ataseven says:

    Hey Dan! Amazing video, it really would have helped me if I had watched it before I broke the lead wire while trying to service it :)) However, I'll do the procedure more carefully the next time I try to service my new one 🙂 love from Turkey.

  9. mardia sultana moni says:

    thank u

  10. jan43482 says:

    Super movie. After watching, I decided to spin and clean my dahon hub. Thank you.!!!!!!!!

  11. ÖMER İÇTÜZER says:

    Not enough

  12. Bernard Chu says:

    thank you this helps me a lot ..please let me see also the video on how you disassemble it from the wheel?

  13. Peter Lange says:

    Nice video. Well done. Thank you very much.
    How does a Shimano dynamo sound when you turn it in order to produce power? Do you know which insulation material Shimano did use?

  14. Joe Kahno says:

    Do keep this in mind. Sometimes an item is not serviceable in the field because correct reassembly requires special jigs or alignment fixtures that were never available outside of the factory. If the choice is try to fix it or throw it away you lose nothing by trying.

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