Service interval of Rohloff's external clickbox

[Andre Jute]

Andre, you could remove and replace the cover screws one at a time with no risk at all.

I was really glad to get some anti-seize on them. Their countersunk heads would make a real hash of trying to remove them if the threads truly seized in place. Worse, the chamfered countersinks are a secondary prime source for galling, so a dash of anti-seize in the wells wouldn't be amiss.

I was just drinking a cup of coffee by my bike, contemplating the click box, and considering the amount of surface that is gallable... Great minds think alike.

[E-wan]

you could remove and replace the cover screws one at a time with no risk at all.

Did this today while I had the bike upside-down to adjust the chain tension. I noticed on removing the screws that they had been secured with threadlock and on the threads there was no evidence of galling but you could see that this had started to happen on the smooth surface of the countersunk bolt heads where they touch the plate for the EXT box (though this is an anodized surface). I decided to refit them with copper slip instead of thread lock. But when refitting them noticed that the recommended torque was only 3nm. As my own Torque wrench is only calibrated down to 4nm I just refitted them by hand.  Just wondered what others do in terms of low torque rated bolts. I tend to find that you can feel more accurately by hand if the thread is about to strip and wouldn’t necessarily trust the sensitivity of a torque wrench even if it was set to stop at 3nm.

Any thoughts on with the thread lock vs copper slip for this application or on whether to bother with a torque wrench at 3nm?

Thanks
Ewan

[Danneaux]

Hi Ewan!

My bolts were dry -- no anti-seize -- and I refitted them with anti-seize on the threads and head.

On really small, low-torque fittings, I generally don't trust my click-torque wrench (most don't give really accurate readings around 3Nm, so use an arm-type bit holder and my scale so I can get a direct reading of actual torque applied. As long as you know the length of the moment arm, you can calculate the needed torque and go from there.

Generally speaking, I don't trust my click-type torque wrenches as much as my beam-types, even though they have been calibrated and are always stored with the tension released. Before using them on anything critical, I always check them against my "beamies" on another fastener. I've found the "clickies" are fine in the midpoint of their range, but go a bit off at the extremes. When it happens at the lower end...the bolt or machine screw can go past yield while you're waiting for the click. I've found it harder to feel when it is approaching that point through a click-type torque wrench, so yes, it is one case where doing it by hand can be better. Best yet is the homemade torque wrench I described above.

Remember to adjust torque downward about 10-15% to allow for the difference in wet vs. dry torque, sometimes called the "K-factor". For an interesting treatise on K-factor as the result of anti-seize, see: http://sw-em.com/anti_seize.htm

Thanks for the photo. Looks like you caught things in time, and it confirms the countersink has a lot of surface area where galvanic corrosion can occur.

Best,

Dan.

[Andre Jute]

I want to service my bike outside. I always do, on the first fine day of the spring. It's the first day of my official cycling year. This year it's so miserable that I've been contemplating doing the service inside. Whichever, it must be soon, so I'm rereading these pages. Very useful. -- Andre Jute

[expr]

I would be tempted to use thread lock (loctite blue 243) on the threads (and) on the inside head mating surfaces. I've found a few people have had problems with the copper grease causing more harm than good. One of them being electrolytic corrosion caused by the copper itself, there seems to be plenty argument for and against using the stuff and I think there were also some threads on here debating the subject. Along with should I / shouldn't I use loctite or copper grease.

Personally I would use loctite 243 all over the screw including the head. This arrangement has allways given me consistent reproducible results and an expected trouble free removal of the screw. The loctite seals all mating surfaces and also allows you to tighten the screw using your feel and touch and then knowing it will be held in that position without coming undone after around an hour of application.

I still believe copper grease has its place, just not on the rohloff screws, I also remember the debate over using it on the small oil drain grub screw, which brought up many interesting points. But remember if you use the loctite you must ensure that the surfaces are clean and oil free to work, this also stops any gauling of the threads which soft alloy is prone to.

Dave.

[George Hetrick]

... this also stops any gauling of the threads which soft alloy is prone to.

Is gauling the threads the same thing as french threading?

[Danneaux]

Hi Dave!

As usual, excellent suggestions all, and proven in your own service; thanks!

The only problem I've had in full-coating small fasteners with Loctite 242 related to the sometimes small bolt sockets used for key removal. I found the bond created by 242 was sometimes greater than the yield strength of the socket, so have limited it to a portion of the threads in those applications, rather than coating the entire mating surface on countersunk heads. For small fasteners, I'd likely be better off with one of Loctite's "purple" (lower-strength) formulations.

You're absolutely correct Loctite does a fine job preventing galling.

243 can be applied to slightly oily surfaces, whereas 242 requires a clean surface ( http://au.iloctite.com/en/threadlocking-solution ), so this may well account for any differences in our experiences. Like you, I have found copper grease is sometimes not appropriate for all applications, at least in my climate.

All the best,

Dan.

[expr]

Hey Dan,

Yep good suggestions, with the weaker solution strength this may well work our better overall. My main concern over using copper grease on the hub screws is that even when torqued up the screws seem to have a willing to come loose, I know from a few topics on the the forum people have suffered from loose or lost screws and ironically have also suffered from seized and broken off heads...

Here what you say with regards to the yield strength and its something that has to be taken into consideration, but can say from experience that coating the full screw has given me good results... I guess a good compromise would be to loctite the threads only and then once seated and cured apply a coating of hard wearing sealant around the periphery of the screw head I can suggest (CT1) this is a fantastic product that I've also used and can fully recommend for many tasks... If I had to compare it, it's like the workability of standard silicone sealent but with four times the strength. It's classed as a construction adhesive, available in many colours.

I guess if some one wanted total protection, it might be possible to source titanium screws to substitute the original ones...

All the best Dan,

Dave.

[il padrone]

Maybe I'm living in a strange world, or simply have exceptional good luck. I never use loctite on my threads, never have any seized up screws, don't use a torque wrench and hardly ever have any screws or bolts come loose.

 

[expr]

Hi, I think for the most part, depending on conditions and what the bike is subject to, that most things will quite happily stay where you leave them, IE: will not fall apart etc.... But loctite along with other products of similar substance can also be a great additive to lots of mechanical things which will aid in the long term serviceability of things.

I have read some accounts which relate directly to the hub screws either seizing up and snapping when removal has been attempted, or conversely falling out due to coming loose.

The hub bolts although connect both half's of the hub shell together are not under full axial load persae, but are rotational load. The two half's connect together with an internal male mating flange to which the main shell receives and locates giving that perfect fit, even with no screws fitted there is no axial movement due to the design, however there would be nothing to stop the end shell from turning and of course keeping the oil in.

One of the main advantages of loctite or similar products is the anti galling properties along with total water proofing of the threads, and what seems to be a predictable outcome with regards to later service expectations.

As Dan has also suggested, putting wet lubricants on threads also has an effect on the final figure dialled in to torque wrenches due to the very nature of the stuff, again I think the use of a torque wrench useful but i believe very much in knowing how to feel when something is tight, this can't be felt through a torque wrench very well. There is a certain point which I'm sure we have all seen at some point either when tightening or undoing a screw or bolt when you just get to the point when that certain (feel) of the bolt shearing comes and then that deep sigh and grrrr of having to remove the remnants of what's left.

With the hub we have the worst possible case, we have a soft alloy shell with steel (bright zinc plated) screws that are much harder than the shell. Once the zinc plating is compromised this allows galvanic/ electrolytic corrosion to take place which allows the screw to expand thus getting tighter, this is why screws get tight, if both mating surfaces could rust then they actually fuse together and cause much more problems. I'm sure we have all found this when working on the car underneath etc....

The problem with most screws seem to be exacerbated when they have been left for a long time and have been subject to weathering etc, I know that there is the old cliche' don't try to fix something that isn't broken, but I don't think it should be taken at literal as it sounds, sometimes by leaving some things this is actually making them worse. I'm a great believer in checking to make sure things come apart and go back together again (within reason) just from a serviceability point of view. On the other hand taking something part to many times can also have a detrimental effect. It's finding that balance and of course knowing when to leave things alone and when to have intervention.

I think in summary, from my point of view anyway and that's not to say I'm right I just go along with experience and real life situations that it wouldn't go a miss to at least check critical screws such as the hub screws (once in a while) if you feel confident to do so. Even more important and I know it's been topic for discussion on here many times that the sprocket is removed even if it goes back on the same way it wouldn't do any harm just to know it comes off. The tools that are used to remove most fasteners make such a difference in the outcome (I'm talking about the quality of the tool) with most tools the more you pay the better they will perform and last, and of course make the job more pleasurable in doing. You just get what you pay for.

All the best

Dave.

[il padrone]

I'd pretty much agree with all of what you say, however this:

With the hub we have the worst possible case, we have a soft alloy shell with steel (bright zinc plated) screws that are much harder than the shell.....
 
.......The problem with most screws seem to be exacerbated when they have been left for a long time and have been subject to weathering etc,

.....sounds like the circumstances of most of the bolts on a typical modern bicycle. Plated steel (or less-commonly, stainless seel) into alloy components. Yet seizing or loosening is really so rare.

I don't even own a torque wrench and have always relied on hand feel.

[E-wan]

I
I used to routinely use Loctite 242 for many applications but was dissuaded form this when getting my nomad built when I asked for it to be used on some of the smaller bolts such as to hold the bottle cages on.  I think that then thorn fitted these the used grease or copper slip, not sure which. So I am now a bit more hesitant about routinely using it.  I have occasionally had trouble removing smaller bolts using Loctite 242 but not to often. Like the idea of trying the weaker strength Loctite and will look into this for next time.

I wanted to ensure the head which had started to corrode was also protected and thought that the added surface area here might make the torque required to release the bolt to large when using Loctite 242 (having noticed that when rholoff or Thorn had assembled the EXT click box they had only used Loctite on the threads). For this application I was less concerned about the screws loosening as the thumbscrew that holds the EXT click box in place also holds the cover on. I know that Torx screws are meant to be harder to strip than bolts that require an alan key but not having much experience of using Torx bolts prior to getting a Rohloff I have little practical experience of the difference.

I wonder if having an anodized hub makes the bolts less likely to seize. But perhaps as suggested a more elegant solution is if Rholoff used titanium bolts for all application on their hub.

Ewan

[expr]

Hi Ewan,

Yes nearly all screws that I've used the loctite on I've only ever placed on the threads, but having read some of the stories regarding the hub screws coming loose I decided to apply the loctite all over. I took apart the screws several times later to ensure the torque required to remove them wasnt excessive and would further cause problems for the removal. Every time they came apart it was with ease and I didn't find any reason to stop using it the way I had. Also noting that the head of the Torx screw had sealed well.

As Dan has suggested, you could use the 242 loctite which is a weaker version of the 243 this would further eliviate any problems down the line...

The scres are also available at thorn cycles as spares so its probably just easier to swap out the corroded ones and replace for new with thread lock just on the threads...

The use of the Torx screws initially (in general) were a form of anti tamper style head, but does offer some resistance to slippage  or ( camming out) like a Philips screw does sometimes when over turned... Obviously the thing to watch out for there though would be how (tight) you go.... As I said earlier using any form of loctite will allow for slightly less torque to be used when doing up the screws as it's the loctite holding the screw in place not the tension of just the screw..

I have no doubt that anodising would give an extra barrier against corrosion and in the long term help keep the hub looking good and working well...

All the best

Dave.

[Danneaux]

Hi All!

After lubing my External shiftbox ("clickbox") I wondered if perhaps I had gone a bit overboard in trying to prevent future corrosion-related problems:
http://www.thorncycles.co.uk/forums/index.php?topic=3325.msg36179#msg36179
http://www.thorncycles.co.uk/forums/index.php?topic=4523.msg36175#msg36175

Seeing a recent photo of what can happen inside a "dry" (unlubed) box, I'm beginning to think I might have done it just in time. The folks over at German maker Velotraum ("Dream Bike") just posted some photos on their blog of a two year-old Rohloff external shiftbox roller extracted from a bike that "According to customer perception and appearance [was a] 'well maintained bike'". See: http://velotraum.de/images/1810.jpg

Yikes!

Best,

Dan. (...who thinks a lube in time saves mine)