Normal freewheeling friction in Shimano Nexus 8? Service recommendations?
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Normal freewheeling friction in Shimano Nexus 8? Service recommendations?
My "new" (about 250 miles at this point) Shimano Nexus Inter-8 hub drags a lot when freewheeling, and with my hand on the pedal a distinct grinding sensation is transmitted (kind of similar to feeling from a freewheel hub with cones adjusted way too tight). If I give the rear wheel a moderate spin, it comes to a stop very quickly (can you tell from this video clip?) Just had the bike in for free after-sale checkup (at Performance Bicycle) and their head mechanic said that it's normal ... but he also tried to upsell me on a bunch of unnecessary stuff, so he doesn't have a lot of credibility with me. But I'll believe the bikeforumers, so what say those of you with this hub? I need to learn how to service it, especially if there's something that needs adjusting or lubricating right now.
Last edited by mc510; 09-12-18 at 04:31 PM.
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Pull it apart, remove core, clean off the grease, in solvent,
then go to an ATF dunk lube.. plan on doing it more than once..
its lighter, so will drag less..
then go to an ATF dunk lube.. plan on doing it more than once..
its lighter, so will drag less..
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You mean clean the grease off the internal mechanism, but keep grease on the external bearings, right?
I see a lot of YouTube videos showing how to do that for an Alfine hub, is it the same for an Inter-8 hub?
I see a lot of YouTube videos showing how to do that for an Alfine hub, is it the same for an Inter-8 hub?
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First thing I think of is chain tension, which is of course no tension. The chain should have a small amount of looseness or it will pull on the cog and therefore the hub's internals. The result of a too tight chain can feel much like that of too tight bearings, because it's really the same effect. Andy
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Alfine 11 is made with oil in mind . you have fill hoses to screw in..
My Rohloff uses a flushing oil that is sucked out after a while , then re oiled.. thru a hose . hypodermic
Alfine 8, is as I understand a Nexus 8 core, with a disc brake mount casing..
as far as axle bearing greasing, I have greased them on my S-A AW 3, and oiled the internals
Through axle, hollow for shift chain ...
Generalizing ; I don't have a Nexus 8, do have a Sram 9, no sticky freewheel issues...
....
My Rohloff uses a flushing oil that is sucked out after a while , then re oiled.. thru a hose . hypodermic
Alfine 8, is as I understand a Nexus 8 core, with a disc brake mount casing..
as far as axle bearing greasing, I have greased them on my S-A AW 3, and oiled the internals
Through axle, hollow for shift chain ...
Generalizing ; I don't have a Nexus 8, do have a Sram 9, no sticky freewheel issues...
....
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BTW, the wheel spin looks pretty normal to me. Of course, my wheels are 20" so they probably have less momentum. As mentioned ^^ make sure your chain has a small amount of slack in it.
Hope this helps.
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It's been like this from day one, not something that's developed after 250 miles.
Chain has some nice slack in it, I corrected that immediately after purchase.
I'll try the oil dip as soon as my clip-spreading pliers arrive; sounds like it might help and can't hurt. I wonder if the cones are also too tight; oil dip will give me an opportunity to adjust those properly.
Thanks all.
Chain has some nice slack in it, I corrected that immediately after purchase.
I'll try the oil dip as soon as my clip-spreading pliers arrive; sounds like it might help and can't hurt. I wonder if the cones are also too tight; oil dip will give me an opportunity to adjust those properly.
Thanks all.
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I don't remove any clips, though I have done and it's not difficult. I simply open the non-drive side of the hub by removing the locknut and cone, then pull the innards out and dip the whole assembly. It's a pretty quick process.
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I tend to agree with the shop wrench to a degree. I've found that many of the modern crop of IGHs do have more drag/friction then external geared hubs do, or for that mater then old generation (SA AW, Shimano 333) hubs do.I wish I was more fluent in modern IGHs so I could tell what was the norm. in running freedom. Andy
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Watching your video, that does not look like an unreasonable amount of drag. Note that the hub is not carrying the chain forward as it freewheels.
One common source of friction with these hubs is between the cog and the dust ring. Nothing but wear will improve that.
One common source of friction with these hubs is between the cog and the dust ring. Nothing but wear will improve that.
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I tend to agree with the shop wrench to a degree. I've found that many of the modern crop of IGHs do have more drag/friction then external geared hubs do, or for that mater then old generation (SA AW, Shimano 333) hubs do.I wish I was more fluent in modern IGHs so I could tell what was the norm. in running freedom. Andy
Last edited by mc510; 09-16-18 at 01:53 PM.
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I’m coming up on my 5th year with my Nexus 8 hub. My comments for what there worth. There are a lot of varieties of these hubs. Look on the hub shell for the actual part number. Mine says SG-8R31. It’s pretty easy to find the exact Shimano manuals using that number. My hub called for service every two years. When I researched it a couple years ago I decided to go with the Shimano grease specified for this model and bought a tube. Other models specify other lubricants. There had been complaints on these forums about ordinary grease being too heavy/sticky and causing shifting problems. Also some had complained that the oil/atf dip caused lubricant to leak out of the seals which could get on brake discs or just generally make a mess. It’s easy enough to open up the hub, clean and regrease. I used normal bike hub grease on the “main” bearings, those supporting the wheel and the special grease lightly applied to the innards, the planetary gears and shift pawls. Been running great. I’m past due for another refresh based on two year interval but I’ll wait until winter for that. Good luck.
Last edited by Joe Bikerider; 09-13-18 at 08:09 PM.
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I went up through step #5 here https://www.sheldonbrown.com/nexus8/pages/13.htm; is that where you stop disassembling and then do your oil dip?
I started using a giant beer mug for the dipping process, but the axle prevents the gear clusters from being immersed unless the mug is pretty much full. So I constructed myself a container that has a tube sticking out of the bottom for the axle. This is made out of a "Talenti" ice cream jar with a plastic syringe (the tube) epoxied to the bottom. The axle drops into the syringe, and a whole lot less oil is required. I just leave the oil in the jar and top it up as needed; the debris settles out into the syringe which has a screw in it for cleaning if I ever feel like it.
There had been complaints on these forums about ordinary grease being too heavy/sticky and causing shifting problems. Also some had complained that the oil/atf dip caused lubricant to leak out of the seals which could get on brake discs or just generally make a mess.
Oiler on its convenient "stand"!
Syringe serves as relief for the axle.
Close-up of the syringe. Some settled debris is seen in the bottom.
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Nice @sweeks, just found an old syringe in the garage and am going to make up a container just like yours! I'm actually not a huge fan of Talenti gelato (texture seems a little over-emulsified for my tastes) but I'll figure something out. I have a quart of Lucas 75W-90 100% synthetic gear oil that should be suitable, no?
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I had a similar question (which is I why I found this thread). I opened, cleaned, and regreased my five-year-old Inter-8 using Shimano's runny grease. There's probably nothing wrong because the hub shifts perfectly and is very quiet. But, I've also noticed that, while coasting, a lot of rotational motion is transmitted to the pedals, carrying them forward very vigorously. And there's quite a bit of friction while backpedaling. The left side bearing isn't too tight, for sure. I don't remember what it was like before I did the service. Could it be the dust cap? It seems to me if something was out of whack inside, the hub wouldn't be shifting correctly and running so quietly.
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BTW, I saw this website from a Seattle bike shop about how Shimano doesn't put enough grease in the hubs and if you ride it in the rain in no time you'll have the corroded, pitted piece of junk they show in photos, and recommending frequent overhaul. After five years all weather riding on mine this had me scared out of my wits.So I opened the hub and.... it was fine. I cleaned it up with mineral spirits and through a magnifying glass I couldn't find a trace of any damage. I regreased it with the Shimano stuff and apart from the backpedaling friction I mention above it seems to be working perfectly. I think it could go another ten years without any worries, assuming I don't ride it into the ocean.
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Attached is an image of two greases: Roller Brake and Nexus hub. There's a small smear of each grease by the nozzles.
Shimano Roller Brake Grease and Nexus Hub Grease
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There must have been a switch sometime. I got my first Nexus hub (7-speed) in 2003 and serviced it soon afterwards. I looked far and wide for the "special" grease, and eventually found some. It was black, as I described earlier. In 2006 I got a bike with a Nexus-8 hub ("plain", not "Red Band"). This hub also was lubricated with a black grease. When, shortly afterwards, I acquired a "Red Band" Nexus-8, I was surprised to find the white grease (like a lithium grease) inside. Now, all these hubs get a "dip" in gear oil at an appropriate interval depending on how much I use the hub. The black grease is placed on the hub bearings.
Attached is an image of two greases: Roller Brake and Nexus hub. There's a small smear of each grease by the nozzles
Shimano Roller Brake Grease and Nexus Hub Grease
Attached is an image of two greases: Roller Brake and Nexus hub. There's a small smear of each grease by the nozzles
Shimano Roller Brake Grease and Nexus Hub Grease
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Hello,
I'd like to dip this SG-8R31 Nexus 8 into gear oil to see if it makes it less draggy, but am stuck removing the core from the hub: It won't come out.
Should I loosen something on the drive side?
Thank you.
---
Edit: You just have to hit the axle more strongly :-p
DONE.
I'd like to dip this SG-8R31 Nexus 8 into gear oil to see if it makes it less draggy, but am stuck removing the core from the hub: It won't come out.
Should I loosen something on the drive side?
Thank you.
---
Edit: You just have to hit the axle more strongly :-p
DONE.
Last edited by Winfried; 02-12-22 at 07:03 AM.
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Grease the bearings and adjust for *zero* play... easier than with a quick-release hub. There's always going to be some drag though... lots of little spinning gears!