"Silent Ring" Removal?

[Beave]

I know, I know. Not much to talk about when your hub just keeps working and working.....

So I am one of those weirdos that doesn't mind an obnoxiously loud ratcheting freewheel. My question is, can the silent ring (Part # 25 on the exploded diagram) be removed w/o dimesionally screwing up the hub? I know it's a really tight tolerance machine, especially axially, but the parts surrounding the silent ring are also spring loaded against each other (I think).

So, I'd do it, but I don't want to waste my oil before the next due change (6 months). With all the dismantlers popping up, just wondering if someone else would do a test run while I wait patiently for my oil to expire.

Not a chance in hell? Yeah, probably. If not, I'll post an update when I get around to trying it.

[expr]

Don't remove the silent ring as you will experience a noise similar to that of a washing machine full of spanners!!!! Trust me.

[Beave]

Washing machine full of spanners!

You know that just makes it more tempting, don't you?

I have to try it. I will try it! I figure I can test run it before I refill the oil and see if I like it or not.

I'll try to post a video or take some sounds bytes before and after. Still gotta wait those 6 months though.

So, Expr, how do you know what it sounds like?

[expr]

Hello Beave,

your slightly missing the point as to the function of the silent ring. The term silent represents the characteristics of that very ring and not of it's function. It's function is to softly engage the clutch ring on to the sun gear, this will not produce a louder freewheel sound. The analogy of the "washing machine" was a generic term for a knacked gear box. The clutch engages when transferring movement to the first set of planet gears this is done when the clutch ring 2 pushes the clutch ring on to the sungear 1, without this there is a potential to have not very smooth transitions between these parts.

Taking the hub apart is a wonderfull thing and establishing what does what is very interesting, but it does have to be built back together in only one sequence. The planet gears are sequenced in a ratio divisible by three which will only allow them to be engaged to the sungears in this configuration. The second set of planet gears are divisible by one.


http://www.photobox.co.uk/my/photo?album_id=168875892&photo_id=239350260#239350260

Dave.

[Beave]

Dave,

I have to respectfully disagree with your description. I know this is going to sound horrible, but I have on my computer a Rohloff video where an employee is walking through the shop and showing the different assembly processes etc. Well, 5 minutes into this 20(?) minute-long video, the employee demonstrates the difference between the clutch mechanism with, and without a silent ring installed.
Well, I found the video, so you can see for yourself. Please see the video here:
http://videos.mtb-news.de/videos/1/_/video/rohloff_kleinm4v.m4v
Note, it is a 86 MB movie, and a lengthly download depending on your connection speed.

I agree with your description of how sun gear 2-2 interacts with the clutch ring (Part # 26), but disagree that removing the silent ring will not make the freewheel noise louder in certain gears. I also don't understand how it would change the interaction of these gears meshing or not meshing smoothly, since they both have "ratcheting ramps" that mate with each other when pedaling, or can slide against and off each other when coasting. Unless you can convince me otherwise, I believe the silent ring is nothing more than a noise absorbent. What remains to be seen is whether or not the silent ring provides some sort of critical spacing, which it would seem is so, as seen in the video when the employee uses a dial indicator to check the tolerance range with and w/o silent ring installed. I don't completely buy that though, since sun gear 2-2 can't move along the axle, and the clutch ring is spring loaded (pushed) into sun gear 2-2 depending on what gear you are in. And I doubt that spring has enough "oomph" to compress or overpower the distance that the silent ring would be responsible for maintaining.

Mind you, I am not trying to be a know-it-all, I just enjoy talking about the hub and how I think it works. Having said that, whether I am right or wrong, I do appreciate your participation in the discussion!

[Beave]

Upon further inspection, (watching the shifting shaft video), it looks like only gears 1, 2, 4, 8, 9 and 11 would be obnoxiously loud (while coasting) if I were to remove the silent ring.

[Beave]

Take a look at these two photos. I'd be interested to hear any different interpretations.
Note that I have fixed the red arrows that had been pointing the wrong direction. 


Freewheel (Large) by climbercraig66, on Flickr
Freewheel Explo by climbercraig66, on Flickr

[Beave]

Another thing I noticed (which doesn't further either argument) is that within the hub, there are a total of 4 almost identical instances of where gears interact in the same way as we've been talking about in prior posts. So, why only 1 silent ring, and why that particular location as opposed to the other 3 similar situations?

[expr]

Hi Beave,

that thought had crossed my mind also, I was planning on taking a revisit back into the hub to investigate more as to what's going on but at the moment I'm head first in plastering walls and trying to work out why my wife's car is displaying 888mph intermittently on the dash.

With regards to the video I have seen that before and yes watching it almost convinced me that its sole purpose was to (SILENT) the interaction of that particular engagement of clutch and sungear, and yes as you suggest when any coasting is taking place the driver and planetary gear is locked in place it basically has no choice as the driver and ring gear are locked together anyway, but i have asked myself the same question "why so much attention to detail" on the clutch ring and sungear engagement when further operations within the hub are also providing an almost identical situation.

This is why my initial thoughts of silencing were more of force absorbsion within the clutch spring forcing the clutch ring against the sun gear. When the hub is stripped down you can see the action of the clutch ring by engaging the shifting shaft back and to, the angle of concentration is around 45deg so it actually gets pushed very quickly in to place.

Obviously the majority of the noise comes from the pawl's which I have to say is quite nice to listen to at times especially when you know you've had all them bits in your hand aswel.

Have you ever stripped the hub down completely.

Regards

Dave.

[Beave]

"Have you ever stripped the hub down completely."

Yes, but only in my mind, thousands of times. Last time I did an oil change, I removed the gear assembly from the hub shell, but I was also preparing for a bicycle vacation, so complete disassembly seemed potentially foolish. I plan on doing my next oil change with no impending plans dictating immediate buttoning up.

I must be missing something, or maybe we are talking about different clutch rings: Are you talking about the one that is engaged during the 7-to-8 gear shift? Part # 14 on Rohloff's exploded diagram? I can clearly see that one in the shifting shaft video, and can also see that sharp 45 degree engagement. I also understand how that one works, with the clutch sleeve over the axle, and the pin protruding into the shifting shaft itself. But in that case, that 45 degree transition happens only once, when shifting from 7-8 or 8-7. However, the video does not show what engages the other (thinner) clutch that the silent ring rides within. I would be interested to have that mystery mechanism explained if we are in fact talking about the same thing.

And my interest continues..... I spent some time with the bike in a stand tonight, listening to the coast/freewheel/backpedaling noises. To my surprise, all gears 1-7 sounded very familiar to each other, as does gears 8-14, although a very distinct (and expected) difference between the high 8-14 and low 1-7 ranges. Funny, I remember more personality from gear to gear, or at least that is what it seems like while I am actually riding the bike. I was able to "tease" some odd noises out while backpedaling, very slowly. This helps nothing though, as the mechanism for backpedal freewheeling is probably the easiest to understand.

Dave, you mention that you believe that the pawls make most of the noise, and I agree to an extent. But, something I noticed tonight, was even in gears 4 and 11 (none of the 4 axle pawls engaged) freewheel noise did not change one discenable bit between gears. It was either the same old "low range" (1-7) sounds, or "high range" (8-14) sounds. But now, this would disprove my original point of "taking the silent ring out would make certain gears (1-2-4-8-9-11) more audible during coasting." And instead, it suggests that taking the silent ring out might make gears 8-14 more audible, or gears 1-7.

Speaking of wives, mine is beginning to make fun of me for watching the same hub strip videos over and over again. Ha! She had no idea she was marrying such a tech nerd. But she likes it when I fix cars and other things around the house, so I tell her I am "practicing". 

[Beave]

Reassembling a stripped hub without the silent ring I'm sure will provide a bit of clarity to this mystery. I can't wait the 6 months for an oil change. The oil goes into a cup, and the answers will come from the workbench! I'll get on it this weekend. Stay tuned.

[expr]

Hi Beave,

Yes were on the same parts I think. As far as I can remember the clutch transfered from 7-8 and conversely back again. Yes the majority of noise all comes from 1-7 with as you say not much audible difference or gear personality, with 8-14 being especially quieter. I have also recreated lots of noises by slowly pedaling backwards while coasting.

With reference to you taking the hub apart, first of all it's easier to drain the oil out from the sprocket lip seal in to a small container. Remove the sprocket and then tip the wheel on it's side in to the container, then remove the torx screws from the flange while the wheel is on a slight angle backwards to catch the remaining oil in the hub casing- to re-use if required until oil change time.

tip the remaining oil in to the oil container for later. Hold the non sprocket side very firmly to release the tension on the two flat aluminium driver nut, when the driver nut is off the hub be carfull as this will now allow the hub to be taken apart, very slowly remove each part in order, the driver Assembly will come off first, and then the planet gear Assembly can be taken off. Take note of which way round parts go, place them down on the bench all the same way that they were facing when you looked at them, now the very interesting part comes with the first set of planetary gears. When you take the first set of planet gears away from the sun gear they will inevitably move from there original position, there is a certain way that these must go back to reinstate alignment of the planets. The planet gears are divisible by 3 this means that each of the planet gears are offset by 33.3%, when you very carfully you will see on the face side of the planets that there are index marks set on them, as you look at the complete planets face on the planet at 12 O'Clock must be central the planet at 20 past must have its index mark biased towards 6 O'Clock and the planet at 20 to must have its planet also biased towards 6 O'Clock - refer to my picture on previous post image 1985 for clarification, this will allow the setting of the planet gears, you will find that it will be easier to fit the planet gears first then drop in the sun gear after. The second set of planet gears nearest the shifting shaft end are divisible by 1 so all the planet gears can assume uniform alignment for fitting,  the only other advice i would give is be carfull with the shims these can inhibit the proper seating of the ring gears if not concentric.
Once the hub is back in shell just after you have nipped up the torx screws give the non drive side a few wacks with a rubber shock hammer, keep the concentration near to the axle, this will alleviate any stress that has been set upon the driver into the main bearing upon rebuild. This is perfectly normal ! You can also tell if there are abnormal stresses on the drive if you spin the pedals back and they come to a quick stop its usually the case that bearing misalignment has taken place. I would normally try this in gear 11.

Also keep an eye  on how the pawls sit within the shaft the pawl springs actually sit on top of the pawls, turning the shifting shaft while the pawls are exposed will make the pawls become disengaged from the shaft and fall out !

Hope this helps

Dave.

[expr]

Speaking of wives, mine is beginning to make fun of me for watching the same hub strip videos over and over again. Ha! She had no idea she was marrying such a tech nerd. But she likes it when I fix cars and other things around the house, so I tell her I am "practicing". 

That is my main hobby "fixing things" and also finding out how things work, I have spent the last 10 years making my own workshop at home ......http://www.photobox.co.uk/album/168936262 which has given me great excuses to take all sorts of things apart. I just cant help myself, if it's working I take it apart to see how it works. 

[Beave]

And so it begins............

But, before I say anything, I must say, that is a superb workshop, Dave! Nice job. I share your interest of "investigation" and am lucky enough to be a tool-maker during the day and handyman at home.

Thanks for the advice. I have heard about the axle whacking and planetary timing before but your description is fool proof. Also a good note for dismantlers: Always begin your disassembly with the hub shifted in gear 4, so that no pawls are active. As Dave said, the pawls will eject themselves if you are in a gear that extends the pawls to lock the sun gears to the axle. So basically every gear except 4 and 11 are a no-no.

Didn't get too far tonight. Just opened up the hub, drained the oil into a cup and set the gear mech in an oil catch to drip dry overnight. It always amazes me how small the gear mech and its components really are. I think I get a swollen expectation after spending hours looking at blown-up pictures and videos. This being my second go-around......... Still amazing!

Another surprise is that I *may* have disproven my "Rohloff Rule" picture as seen in a prior post of this thread. I messed around with the gear mech in gear 4 and found that when mimicking a coasting situation, it seems as though all gears are locked all the way over to the sprocket side, where the last planet set spins within the ring gear that is directly connected to the sprocket. So much for having that figured out. But then, spinning it by hand is not exactly the same as having it being spun by wheel momentum. So I am not sold on it yet.

Tomorrow I have a friend coming over with car troubles, so that might delay my progress. But my plan is to make a mock wheel that I can attach to the output planetary set so that I can remount the hub onto the bike, pedal it up to speed and maintain some momentum while investigating what is doing what during coasting. I remember from my last hub opening, that when trying to observe the same function, the gear set quickly comes to a stop with no wheel momentum to continue it rotating. And as we were talking about before, I don't want to recreate the "go slower, hear different noises" situation. I have a thin rubber strap wrench that I think will work perfectly for the base of this project.

Then, as promised, I will remove the silent ring and reassemble. If all goes well, I'll take it for a ride around the neighborhood and report back. If all goes South, I'll report that too.

[expr]

Wow, tool maker I need to know more.... what do you make etc... what car are you looking at and what's wrong with it. I've just bought a snap-on solus pro scanner for our cars !!!! Yeh i know more techno whiz for the workshop but it's great for fault finding etc. you can look at the live data from the sensors, lambda sensor mass air flow, manifold absolute pressure, knock sensor, the list is long but very informative. A lot of cars are using WRAF wide range air fuel ratio sensors now instead of oxygen sensors. They give a much better spread of air fuel proportional output vs the older lean/rich short output sensors, and they run a lot hotter as well around 600 deg. When everything is running in closed loop mode then this is called stoichiometric this is where the perfect balance of air fuel mix is at 14.7 / 1 which gives full burn.

With regards to the pawls don't worry to much about them coming out, very easy to put back, just have a look at how they go before they get removed etc. using a small pick to lift the two legs while putting the pawl back underneath, as i suspect you will not be happy with just looking at hem your fingers will want-to wander!!!!

We might want to take other discussions over to the Muppet's threads and anything else category, i tried to widen the scope of talk but not allot of people have taken me up on it....

Speak soon

Dave.