A step-by-step tutorial on how to service Shimano Nexus gear hubs without any special tools or lubricants:
Relja
Relja
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Shimano Nexus gear hub service/overhaul
- Thread starter BikeGremlin
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An Alfine 8-speed is shown, not mentioned in the video I think.
Please also consider these important points:
1. After cleaning with solvent, let it dry for a day so there is no more solvent left deep inside the gears, else it will thin the new oil.
2. The whole internal assembly must be submerged in oil as directed by Shimano. I believe this is necessary so oil can penetrate deep inside the geartrain. Particularly important are the planet gear pins (axles) and needle bearings, which see a lot of pressure and wear. Oil may not get into these bearings by applying oil from a can or eye dropper.
3. After submerging in oil, I believe the reason Shimano says let drain for only 90 seconds is, they want some oil left inside so it can drain into the hub shell once everything is put back together. This forms a small oil bath that the gears can run through and get continuous lubrication, much like a crankshaft dips into the oil sump of a car engine as it rotates.
4. No lubrication is necessary on the external gear selector ("cassette joint" in Shimano speak). This will only attract dirt and get in the way of the shift cable winding around the pulley, possibly making shifts inaccurate. There are actually no parts sliding against each other in the cassette joint ... the 2 sections of the cassette joint are fixed to the axle assembly with separate splines, and bearing takes place on the axle assembly. Study how the cassette joint mates with the axle assembly to understand this.
5. There is no reason to check if the planet gears are synced because you haven't taken the geartrain apart. (Doesn't hurt to check.)
6. I like to take the hub apart down to individual components to get them really clean. I think that makes it last longer. But don't take the axle assembly apart, that's a real pain to put back together with the springs (even though there are videos showing how).
Please also consider these important points:
1. After cleaning with solvent, let it dry for a day so there is no more solvent left deep inside the gears, else it will thin the new oil.
2. The whole internal assembly must be submerged in oil as directed by Shimano. I believe this is necessary so oil can penetrate deep inside the geartrain. Particularly important are the planet gear pins (axles) and needle bearings, which see a lot of pressure and wear. Oil may not get into these bearings by applying oil from a can or eye dropper.
3. After submerging in oil, I believe the reason Shimano says let drain for only 90 seconds is, they want some oil left inside so it can drain into the hub shell once everything is put back together. This forms a small oil bath that the gears can run through and get continuous lubrication, much like a crankshaft dips into the oil sump of a car engine as it rotates.
4. No lubrication is necessary on the external gear selector ("cassette joint" in Shimano speak). This will only attract dirt and get in the way of the shift cable winding around the pulley, possibly making shifts inaccurate. There are actually no parts sliding against each other in the cassette joint ... the 2 sections of the cassette joint are fixed to the axle assembly with separate splines, and bearing takes place on the axle assembly. Study how the cassette joint mates with the axle assembly to understand this.
5. There is no reason to check if the planet gears are synced because you haven't taken the geartrain apart. (Doesn't hurt to check.)
6. I like to take the hub apart down to individual components to get them really clean. I think that makes it last longer. But don't take the axle assembly apart, that's a real pain to put back together with the springs (even though there are videos showing how).
Yup - edited the title. Thanks.
The new 11-speed Alfine has an oiling port, a lot like Rohloff (in terms of procedure), while the 8-speed Alfine is a lot like Nexus 7 and 8-speed.
There is the Shimano's recommended procedure (with their internal gear hub grease), and several "alternative" options. The procedure shown is what's worked well for Mićko - he loves and rides geared hubs a lot. Quick, simple, and using cheap automotive lubricants.
Relja
Relja, thank you and Micko for your video, when I was looking up the Shimano recommended technique for servicing the hub, it did not make sense that an internal hub that came from factory with grease, to just dip it into oil, also the price of the Shimano oil. Other option of dipping in ATF also did not seem right. your version of applying basically grease on the gears and oil on the rollers made more sense.
I did complete the service on my Alfine 8 speed hub and my bike and I are much happier as a result. Couple things, the blue dots you showed for aligning the gears to put back together were not present on mine, however the tab that you showed helped to line it up and a little jiggling was enough to put it back together.
My question (at end of post) is when I was cleaning the inside of the external shell or body of the hub, I found this ring, circled in red in photos. It was sitting in a groove of the hub body. I have the schematic view from shimano, it is not listed. When watching your video and several others it was never mentioned. I am not the original owner it was installed on a Masi Soulville that I bought. It is set up with a gates belt drive. Which in combination with an internal hub makes it a low maintenance drive train. The frame was not made for a belt, previous owner made a small cut at rear drop out to insert belt into rear triangle but that is another story
Do you know what the function of the ring is? Is it necessary? I hope I reinstalled correctly
Attachments
Hi,
I'm not 100% sure if you've put it back where it was (don't have any such hubs or schematics at hand now), or if you did, I'm not 100% sure if it was originaly put where it's supposed to be.
I'd have to ask Mićko.
Which model of the hub is it (it should have a model printed on it)?
Generally, such internal snap rings are used to keep stuff in place, and I've seen Shimano use the notch on its end to keep stuff aligned in a way - this video should open at the part where I'm showing that on a freehub (25:19):
https://youtu.be/M-CGiRdNlCQ?si=YLu-Hioth2ceoU8p&t=1519
Relja
Relja,
thank you for reply. Hub model is SG-S500 (see photo)
I have also attached the Shimano schematic for the hub. I did not expect to find a ring like that, so during disassembly, did not pay attention to exactly where it was located. Just assumed that it should be in the groove part of the way up the internal wall of hub body, or maybe it belongs all the way deep at the 90 deg angle where wall of hub parallel to axle meets internal surface of hub parallel to fore/aft plane
Bob
Attachments
Hi Bob,
Thanks for the schematic pdf - it does help.
As far as I can see, there is only one ring that resembles the one you photographed, and that one is a bit flat profiled.
Part number:
Y-34R 80000
What it looks like:
https://www.sjscycles.co.uk/hub-spares/shimano-nexus-sg8r20-ring-gear-1-stop-ring-34r-8000/
Pages 86 and 87 of the manual I attached to this post show some snap-rings used on on some models. I couldn't find a service manual for your SG-S500 model, but I hope this gives at least some idea of where a snap ring might go (use your own judgement about whether it makes any sense for your model).
Relja