Alfine 8-speed ?clutch? problem in gears 2, 3, 4

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LuckyLuke
Posts: 232
Joined: 10 Jun 2010, 11:54am

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby LuckyLuke » 30 Nov 2017, 9:54pm

Hi, thought I'd share about my recent Nexus 8 shifting woes, and how they were resolved.
I had a 4yr old Nexus 8 hub, neglected for 2yrs, then I took the plunge to give the innards a soak in gear oil once a year.
It did develop some hub slipping after one soaking and reassembling, which I think may have been due to incorrectly adjusted hub bearings, as on readjusting them the slippage resolved.
Slipping returned on out of the saddle accelerations and I fitted Jagwire cables as advised on the forum (thanks all). This greatly improved matters.
Slipping did return though after 2-3 months. I then replaced the cassette joint (CJ-8S20) with a new one. Comparing the two, there was noticeable play on the old one. The yellow alignment marks on the old one had worn off, so I was aligning it by the marker on the underside. On fitting the new CJ, using the existing cable, I recall having to tweak the barrel adjuster to align the new CJ correctly, suggesting the old one was off.
I rode it for a couple of weeks and to my delight it didn't slip. I then gave it to my brother in law. I've had no reports of slipping in the month or so he's had it (crosses fingers, touches wood).
Best wishes,
Luke

Brucey
Posts: 36756
Joined: 4 Jan 2012, 6:25pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby Brucey » 1 Dec 2017, 6:36am

for the timing marks to be accurate, there are multiple parts that have to be manufactured and then to fit together properly. Between manufacturing variations and wear of mating parts, it isn't that unusual for the timing marks to be in error.

I have seen

- hubs in which a new CJ still gave a timing error. There was no evident wear on the mating castellations on the hub.

- CJs which gave slightly different timing depending on whether you use the top or bottom marks

- Hubs in which the axial clutch wasn't timed correctly vs the pawl lifts (typically giving a slippage in gear 5 when correctly adjusted for other gears)

Worrying about any of this is pretty pointless unless the cable is in perfect condition and everything is clean etc. When overhauling a hub of this type I check that the pawl lifts etc are correct vs the timing marks on the CJ that is fitted to the hub. If they are not, a correction is made when setting up the hub and if necessary a new slot is cut in the underside of the CJ clearly showing the correct timing to use.

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

AndrewJR
Posts: 14
Joined: 26 Nov 2017, 10:58am

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby AndrewJR » 4 Dec 2017, 9:40am

Been out of the country for a week, just going through all the posts. I'll check my cable again, but in the original post I did stress that I had already checked it quite carefully. In my personal case I do not think the problem is cable (alone). I started at the aligned position (using the bottom marks, as my top marks are worn away, or at least unreadable as the windows are not very transparent any more), and tried all combinations of settings in 1/4 turn adjuster increments over a wide range. I never made any improvement, and I did not notice any tendency for the markers not to re-align in an up or down direction. I'll check it again, but I'd be surprised if I managed to fix my exact problem with a cable change (alone).

What I did establish this morning is that I can slip it in 2, 3, 4 (and 4, quite easily now), but NOT 5, which still feels rock solid, like gear 1.

So, one last check of the cable, or, (for me, in my case, I think more likely) it sounds like perhaps bearing adjustment, or the cassette joint - something which is affecting the clutch on gears 2, 3, 4, (and perhaps 6, 7, 8 ).

Here are the most relevant quotes which I picked up (aside from all the comments about cables).

There are two (roller) clutches that take the drive onto the hubshell (one used in gears 1 and 5, the other used in 2,3,4,6,7,8 (*),(**), a sliding clutch that is only engaged in 5-8, a roller clutch (or pawl clutch in some variants) that is used in 1-4 (*) (and is takes the drive from the driver to the primary ring gear) and three pawls that lift from the axle and are used in 2,6 or 3,7 or 4,8 (*), (**) respectively.


The secondary ring gear to hubshell roller clutch is, I think, spring preloaded. There is a cage around the rollers that is free to slide a little and it is preloaded very slightly in the drive direction by a small spring. If this spring is broken, absent, misplaced, or the cage is too sticky, or rollers are misplaced the roller clutch may slip under load. If the hub bearings are not correctly adjusted (or for some other reason eg a bent axle) the parts are not perfectly concentric, the roller clutch will slip under load. It may well feel like a 'soft' slippage, and may not make much noise. It is easy enough to check the condition of this clutch since it is on the outside of the internal parts when they are removed. If the hub is so worn that the rollers may drop out of the cage, the roller clutch should be renewed. If the steel drive band inside the hubshell is broken, again there may be problems.


It did develop some hub slipping after one soaking and reassembling, which I think may have been due to incorrectly adjusted hub bearings, as on readjusting them the slippage resolved.


I then replaced the cassette joint (CJ-8S20) with a new one. Comparing the two, there was noticeable play on the old one. The yellow alignment marks on the old one had worn off, so I was aligning it by the marker on the underside. On fitting the new CJ, using the existing cable, I recall having to tweak the barrel adjuster to align the new CJ correctly, suggesting the old one was off.
I rode it for a couple of weeks and to my delight it didn't slip.


Andrew

Brucey
Posts: 36756
Joined: 4 Jan 2012, 6:25pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby Brucey » 4 Dec 2017, 9:57am

I often repair and overhaul hub gears for LBSs where they cannot or will not do it themselves. I recently (at their behest, reluctantly) stripped a 'faulty' IGH down and serviced it. I say 'reluctantly' because it seemed to me that the main problem was that the cable was bad. Whilst preventative maintenance in the hub (better lube etc) is always a good idea, in this case IMHO it constituted an unnecessary immediate expense and would be unlikely to resolve the problem.

I stripped the hub and (as I expected) there was no sign of any problems inside, but the same operational faults persisted. I then had to persuade the LBS that there was a cable fault, and that the problems were most likely due to this. Eventually the cable was changed and the hub immediately started to behave itself.

In this case the cable was so bad that a new inner and outer were required (inside, it looked like someone had lubricated it with instant coffee), but most cable issues are fixed with a new inner alone which costs about £2.

The test I have suggested (upshift and downshift to the timing marks, and look for any difference) is quite a good one. The cable in the above instance very clearly failed this test, yet the LBS were (for some reason) reluctant to change it.

Don't be reluctant to change the cable; it should be the first thing you change, not the last. A new inner is a £2 part and the worst case is that you have a spare cable you can refit should the need arise. I would bet money that the cable you have isn't even lubricated correctly, too.

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

Roadster
Posts: 443
Joined: 26 Jul 2016, 2:12pm
Location: E.Lancs/W.Yorks border

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby Roadster » 4 Dec 2017, 5:19pm

It's telling that the problems only started after the service, whereas an already developing fault within the hub might have shown itself sooner. It seems a bit of a coincidence, to say the least.

Brucey
Posts: 36756
Joined: 4 Jan 2012, 6:25pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby Brucey » 4 Dec 2017, 5:31pm

Roadster wrote:It's telling that the problems only started after the service, whereas an already developing fault within the hub might have shown itself sooner. It seems a bit of a coincidence, to say the least.


it still could be the cable, since the weather has turned cold since the service too. Cold weather often puts the final nail into an iffy cable's coffin. So can accidentally kinking the cable when the rear wheel is removed, or allowing the rubber boot to be dragged into the cassette joint (which would tend to affect gears 2,3,4 mostly, BTW).

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

Roadster
Posts: 443
Joined: 26 Jul 2016, 2:12pm
Location: E.Lancs/W.Yorks border

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby Roadster » 4 Dec 2017, 5:40pm

Yes, that's what I meant. I too suspect that the cause of the problem lies outwith rather than within the hub itself, and was created or exposed during the machine's reassembly following the service.

peasantpigcyclist
Posts: 13
Joined: 12 Apr 2012, 9:22pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby peasantpigcyclist » 8 Dec 2017, 7:58pm

I agree with Bruce. Cables are the commonest problem with all gears in my experience,derailleur and hub.
I recommend replacement of inner AND outer.
The problem is that the indexing is in the shifter not the hub. So cable friction is critical, white or black powder (electrolytic corrosion) happens when moisture/water becomes trapped between inner and outer.
Also in sub zero temperature this moisture freezes,expands and causes the extra friction or even total seizure of the cable, hence feeling of jammed gears in the morning which miraculously cures itself on your ride home in the afternoon when it warms Up! (this happens to brake cables too...with scary consequences!)
It's always best to replace both cables every 12-24months to ensure smooth gear changes.
Always check /replacethe cheapest components first.
For the record, pinion and rohloff have the indexing within the gearbox /hub thereby not relying on cable friction and shifter to engage the gears into the correct position.
Good engineering practice!!!

AndrewJR
Posts: 14
Joined: 26 Nov 2017, 10:58am

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby AndrewJR » 9 Dec 2017, 9:22pm

Update on this one. I still don't know what it is but I'm pretty sure it is not the cable.

Basic tests:

Up the hill outside our house. Adjusting the cable any amount with the adjuster, either in or out. Can't make any improvement in any of gears 2, 3, 4,
The most telling experiment is that I can set it up in gear 4 (yellow dots aligned, checked by turning the bike upside-down), and then immediately (without touching the shifter at all), try cycling up the hill and make it slip by stamping really hard. At the top, I turn the bike upside-down again and check that the yellow dots are still aligned (they are). So, I'm not using the shifter or asking the cable to move, and the alignment is perfect, but the problem is still there. I can repeat the experiment with different offsets from perfect yellow-dot alignment in gear 4 (again, without making any shifts or asking the cable to move), and have never managed to have any positive impact. So, in my case, the cable is not the issue, unless some magic cable can affect what's going on inside.

We rang Shimano tech from the bike shop. They say that for the SG-S501 they don't ship any spare internals to the UK any more, and they recommended replacing the internals as a entire new one-piece, which is about £200. There seems little point disassembling the thing and finding a problem right now, since we can't get any individual new parts from Shimano.

So, my approach at this point is just to ride it in a slightly different style. All shifting is still crispy smooth - the problem is only when you really stamp on gears 2, 3, 4. So I'm always starting from the lights now in 1, not 2, and I don't stamp too hard on the hills or accelerating until I'm in either down in 1, or up in 5. I'm just going to ride it this way until it dies, or spring comes and I can be bothered to disassemble the whole thing and attempt a diagnosis, although it sounds like this is probably futile since spare parts aren't available.

I'll emphasis, the hub is still totally reliable in "normal" use, and the actual shifting is still totally smooth and noise-free. If I ride it a certain way, I can get to work and back and hardly notice it. It's only when I apply a lot of torque in 2-3-4, normally at low speed.

It could just be worn out. I have a feeling temperature could also be involved - the service coincided with a sudden drop in temperature. Perhaps there is congealed grease somewhere, or dirt got in during the service (it was very dirty when I put it in the shop!).

Don't know !

Brucey
Posts: 36756
Joined: 4 Jan 2012, 6:25pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby Brucey » 9 Dec 2017, 10:42pm

stamping really abruptly on the pedals (i.e. from freewheeling) can make these hubs do all kinds of weird things, even when they are in good condition. If pushing harder on the pedals (I.e. when the gear is already 'in') causes a slip then the hub is probably faulty.

To get drive in gears 2,3, 4 you need two roller clutches to engage (one on the ring gear in stage 1, one driving to the hubshell in stage 2) and the relevant pawl to be fully lifted in the axle and engaged with the corresponding sun pinion. That it doesn't slip in gear 1 suggests it is not the stage 1 roller clutch.

Occasionally the axle is distorted enough when the wheel is installed so that the shift control is baulked, and various gears go wonky. But if the hub only started to misbehave when the service had been done it is odds-on that something that was done made the difference.

Ways the 'service' might have done this include

- track nuts too tight/frame not aligned (axle distorted, shift control baulked inside the hub)
- lathering too much thick sticky grease on the axle, which inhibits the pawls from lifting fully
- use of a lubricant with too many friction modifiers in it (so that roller clutches slip)
- loss of rollers from the roller clutch
- loss of preload on the roller clutch
- timing marks misaligned w.r.t. the pawl lifts

the last thing can occur anyway, but you would presumably have noticed before; even so the only way this can be checked is to strip the hub and to work the axle assy with the CJ from that hub attached.

Loss of preload on the roller clutch is commonplace, and makes the hub slip badly. IIRC there is a tiny spring that preloads the roller cage; this is easily misplaced or misassembled and the result is that suddenly the hub doesn't work properly any more. If the roller clutch is a bit worn, it is sometimes able to come adrift when the hub is taken apart (spring moves, or rollers drop out). Anyone who has taken a few of these hubs apart would know that and act accordingly. The same clutch is used in 6,7,8, but the applied torque is less, so slippage is less likely.

If a hub has dried grease in it, adding oil is occasionally counterproductive; the grease soaks up the oil, and if the mix is wrong (not enough oil), the grease becomes incredibly sticky and causes all kinds of spring loaded parts (that didn't have any grease on them before, because it had been pushed out of the way long ago) not to move freely any more.

If you are replacing the internal, you are looking for part number Y37N98010 (when googling try various different punctuations such as Y-37N 89010 etc). The statement 'they don't bring these into the UK any more' to me translates as 'Madison are not doing their job properly'. The spare internal is listed as available on amazon and other places.

http://bike.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/SG/EV-SG-S501-2788C_v1_m56577569830714875.pdf

If it were my hub I'd strip it and take a look at it. I'd be reasonably sure of fixing it, too. But then I have done it many times before....

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

AndrewJR
Posts: 14
Joined: 26 Nov 2017, 10:58am

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby AndrewJR » 10 Dec 2017, 10:12am

Brucey,

Thanks. Some of these possibilities sound plausible, based on what I see/feel/experience. On the second day back after service, I dropped the wheel out and did notice that the bolts were pretty tight, and it did seem to me that perhaps, after I loosened the first one, there was just a tiny bit of movement in the axle - kind of a slight springing to a new position defined by the position of the nut on the other side which was still tight, and my feeling was that I made a slight improvement by simply re-installing the wheel the way I'd normally do it - tightening both nuts a bit each alternately, checking that its still seated properly on both sides, before cranking either of them up tight. Of course I cannot repeat this test - there was only the one shot to observe it. If the shop has done anything wrong I think that is the most likely. Perhaps my shaft is ever-so-slightly bent. If it is, it must be very subtle, because the whole thing runs true, no play, no bad sounds during normal operation. When it slips it never just keeps slipping, it just goes perhaps 1/5 revolution and then rebinds. On a really steep hill it can do this in sequence as I pedal, but there is always a slip-rebind cycle if it does happen. This would fit with something asymmetric or warped with the clutch elements.

I think all the other grease/oil comments are viable too, although I think they only did the bath in Shimano - he didn't talk about greasing the internals. The service did coincide with cold weather too.

My shop can get the internal from Shimano - thanks for the part #, its just that Shimano apparently don't import the separate parts of it - you have to buy the whole thing as one - well that's what they told my bike shop owner.

Next time I'm in the office (it's warmer there), I'll drop the wheel off again and see if I can seat it again any differently. Although, I suspect if it is slightly warped now, my chances of being able to un-warp it are very small.

Andrew

Brucey
Posts: 36756
Joined: 4 Jan 2012, 6:25pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby Brucey » 10 Dec 2017, 10:46am

Re buying parts for the hub; without a positive identification of the fault, you would be faced with a choice of buying an axle assy or a gear cluster; if you buy both parts, it is liable to work out as expensive as a complete new centre.

If the axle is strained into a slight curve when it is tight in the frame, this is likely to cause gear selection problems in use but

a) if you upshift to a given gear, then loosen and retighten the track nuts, that gear should be good. Also

b) the axle is unlikely to permanently bend as a result.

Axles do occasionally break on 8s hubs; those who suffer this seem to be offroaders who use very low input gear ratios and low gears a lot, and/or those who don't allow the NTWs to share the load. For example if the track nuts are not tight enough and/or that the NTWs are not correctly fitted each side.

The fact that you get the same sized slip every time is strongly suggestive of an axle pawl slippage. Pawls do chip or jam occasionally, but the #1 cause of this is poor adjustment, IME. On a typical 8s hub, the 'window' for correct adjustment is less than +/- 0.5mm wide. The gears will 'be there' outside of this range, but will slip in exactly the way you describe. It is possible for the marks on the CJ to tell you lies, by virtue of wear and/or manufacturing errors. The errors can amount to ~1mm or so quite easily.

One evil fault is if the cable housing is routed badly to the rear hub, so that the 'fixed' half of the CJ in fact moves when you use the shifter, and/or is not pulled fully CW against its detents all the time. This is liable to make both accurate gear adjustment and accurate gear selection a nonsense, even if everything else is OK. Movement here also (over time) wears the fittings on the hub so that the CJ cannot work properly or be accurately positioned. The part on the hub that locates the fixed part of the CJ is a chrome-plated zinc die-casting; once this starts to wear it goes very quickly and wear here invariably means the hub isn't going to work properly. If the fixed part of the CJ has more than just a little backlash in it, something is probably worn and the gear adjustment won't be accurate.

If the NTWs are not installed/working properly the CJ can be strained as you pedal, which can also lead to gear slippage.

You say you have tried various different settings for the cable adjustment in a single gear; it will take a while, but might be worthwhile to repeat that experiment, having checked the security of the CJ and the NTWs. This time use small increments (of 0.5mm, i.e. about two clicks at the shifter barrel adjuster) to swing from -1.5mm to +1.5mm from the 'correct' adjustment. After each cable adjustment, downshift to first gear and then upshift back to 4th, just in case the cable is a bit draggy. Make sure that the adjustment has not altered after every test, too.

I have encountered numerous hubs that manifested symptoms similar to yours. Most of the 'faulty hubs' were cured by simple stuff, like attention to/recalibration of the CJ and a new cable.

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

John_S
Posts: 329
Joined: 16 Sep 2014, 10:34pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby John_S » 10 Dec 2017, 4:34pm

Hi AndrewJR,

Firstly I'll apologise in advance because I'll hold my hands up to not being technical at all and so I'm afraid that I can't offer you any further mechanical input or advice on this subject. However you've already got loads of in-depth and great advice from Brucey and others above so hopefully a lot of the issues have already been covered for you.

However as somebody with an Alfine 8 SG-S501 hub I thought I'd jut share some of my experiences. I recently had a major problem whereby the IGH was constantly slipping out of gear but that was diagnosed and down to a damaged cassette joint which was replaced and that helped massively to alleviate the acute symptoms of the hub constantly slipping out of gear on my commute.

Despite solving the problem of the contact slipping gears that doesn't mean that it's now perfect. In fact it's never been perfect from day one of having the hub. So basically having replaced the cassette joint I'm back to the point I was originally before the CJ was damaged. And that is whereby it now just occasionally slips out of gear every so often. More often than not this is under load such as when going uphill or setting off from a junction.

Now I'm a commuting cyclist only and I'm not a big guy putting out loads of watts and power. I'm always careful with this bike and IGH combination because ever since I've owned it it's had the habit of slipping out of gear sometimes when under load and so I'm carefully never to quite trust it. Therefore I do try to pick a gear where I'm spinning as opposed to mashing and whereby I'm hopefully not putting too much load/pressure on the IGH but that doesn't prevent the slipping entirely.

However I still like the hub because I think it's a great option for commuting and I much prefer it over derailleur options for an everyday all year around commuter. Yes I'd like it even more if it worked perfectly and never slipped gears at all. In my head I always put this down to the product having been manufactured to a certain price point and not being as mechanically sound as a Rohloff which I'd hope would never slip out of gear. Now I don't know whether or not I've too readily accepted the slipping gears and whether I should have expected more from the hub or not. I just sort of accepted it as a bit of a idiosyncrasy & limitation of the hub that I need to be aware of during use.

But now that I'm reading your post maybe I should never have accepted this in the first place and maybe there's been some sort of fault with mine since day one.

I apologise if this does not add much to help you fix & solve your problem but I just thought that I'd post this to say that you're certainly not the only one who has these issues with this hub.

Good luck solving your hub issues.

John

peasantpigcyclist
Posts: 13
Joined: 12 Apr 2012, 9:22pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby peasantpigcyclist » 10 Dec 2017, 11:53pm

Again, am with Brucey on this. grease that is too thick will cause the pawls to stick in the freewheel position, overcoming the strength of the pawl spring. Diluting the grease with a gl4 gear oil will help alleviate sticky pawls. This was a common problem with some DT Swiss cassette freehubs a few years ago. It may be best to return the wheel to the lbs that serviced it and ask them to look at the hub internals again, suggesting a sticky pawl problem. Internal hub gears generally, are reliable, and do last many years in my experience.

meandros
Posts: 58
Joined: 1 Jan 2018, 7:34pm

Re: Alfine 8-speed ?clutch? problem in gears 2, 3, 4

Postby meandros » 2 Jan 2018, 3:05pm

As long as we're not sure exactly what the service procedure was, it is safe to assume it was done incorrectly even if following Shimano instructions.
Regarding sticking pawls, I'd like to share my experience with a Nexus 8R25 I had bought 2nd hand for an every-day city/trekking biker. The hub experienced slipping gears and non-engagement and crunching in most/some gears. Upon inspecting it, it was filled with original Nexus white grease. I cleaned it, made sure all the innards were assembled correctly and dunked it in ATF Dexron III H. As opposed to the mink oil Shimano sell, ATF has a big advantage in that it acts as a detergent as well keeping dirt and shrapnel suspended. In my experience, no Nexus or Alfine hub should be lubricated with grease only or oil only. In fact, a combination of the two is most efficient. A thick marine grease for the bearings, bearing races and seals and a good dunk in ATF is what works best for my IGHs. It also helps to squirt in a half dozen or so ml of ATF (just enough that it doesn't spill over) before reinserting the innards.
In conclusion, upon having it clean and properly lubed, making absolutely tripple sure the cable end nut to aluminium ferrule is precisely 101mm (with the shifter ferrule fully turned in and all cable tension released) and having a clean and unworn cassette joint, there is really not much that can go wrong. The bearings should be adjusted with no play, as instructed on Sheldon Brown's website.