Campagnolo Over Torque Left Crankarm fell off

Back by popular demand, the general all-things Road forum!

Moderator: robbosmans

User avatar
corky
Posts: 1732
Joined: Thu Jul 06, 2006 5:53 pm
Location: The Surrey Hills

by corky

If I remember correctly I could get it on but not fully by hand....

When it came off I was only half a mile from home, managed to get the crank on and rode home by ensuring my pedal stroke was only in a forward direction......I had lost the lock ring...... went back the following day and found it.....to this day I can't believe it, especially as there was snow on the ground!

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
Calnago
In Memoriam
Posts: 8612
Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

@alistaird: your description is indeed how I would expect the crank to go on the splines... requiring significant torque to get it flush with the spines. Also, yes... by "preload" I'm kind of using that a bit generically here but yes the adjustment of that ring at the very end is I guess what they call "mechanical preload" intended to just remove any gap/play in the system.
And aren't there two special tools involved... one to torque on the crank, then the other 4 pinned tool to torque the closing ring to 8-10Nm? It's that last tool that I'm wondering if they used correctly because it would seem that it might be easy to use something else and end up applying much less torque than required.
And one last thing, if it's possible to "overtorque" the crank further onto the splines more than it should go, then couldn't that possibly be enough to cause some excessive wear, in much the same way as if you were to overtorque an old square tapered crank/spindle situation?
Everything you say makes sense @alistaird and at this point, you're the expert here.
Last edited by Calnago on Mon Nov 28, 2016 4:21 pm, edited 1 time in total.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

User avatar
maverick_1
Posts: 742
Joined: Tue Sep 11, 2007 4:20 pm
Location: Tokyo

by maverick_1

@corky,

I guess you were lucky back then!

Rather than looking for just the left crankarm, the other alternative is to purchase a brand new OT crankset which I hope to avoid :(

User avatar
maverick_1
Posts: 742
Joined: Tue Sep 11, 2007 4:20 pm
Location: Tokyo

by maverick_1

@Calnago
Yes, that's what I suppose actually happened.
Overtorque (left arm went beyond the axle) which then causes excessive wear and an abnormal amount of play.

User avatar
alistaird
Posts: 279
Joined: Thu Jul 21, 2016 8:21 pm

by alistaird

Calnago wrote:And aren't there two special tools involved... one to torque on the crank, then the other 4 pinned tool to torque the closing ring to 8-10Nm? It's that last tool that I'm wondering if they used correctly because it would seem that it might be easy to use something else and end up applying much less torque than required.
And one last thing, if it's possible to "overtorque" the crank further onto the splines more than it should go, then couldn't that possibly be enough to cause some excessive wear, in much the same way as if you were to overtorque an old square tapered crank/spindle situation?
Everything you say makes sense @alistaird and at this point, you're the expert here.


I bought 1 tool which effectively has three parts - one for installing and torquing the crank, one for removing the crank and one for the 4 hole lock ring. They all fit and work together though to enable installation and removal.

I've not tried to torque past the 'flat screwdriver' test...

A

carlcurry
Posts: 37
Joined: Sun Nov 03, 2013 3:49 am
Location: Sherman Oaks, CA

by carlcurry

At around the 3 o'clock position in your picture that NDS arm looks abnormally worn. I wonder if at first installation it was not meshed together properly and redone, or forced too far onto the spindle and backed off? Just a guess of course. I do have two Overtorque cranks, one of which I haven't inspected in over a year. This thread got me curious and I went and pulled the lock ring on both. Both crank arms were fine.
Personally I do not assume the lockring is solely responsible for keeping the crank arm in place. The crank arms on mine fit to the axle splines pretty tightly. I definitely do not overtighten the lockring as I find the 4 holes tightened with the installation tool to be finicky to deal with and remove. I can also say I would not be able to set the NDS crank arm just by hand. I must use the installation tool with some force applied to get it correctly seated.
Sounds unfortunate, but a NDS OverTorque arm that can be seated by hand sounds like a real issue. Any chance it is still under warranty?
Bianchi Infinito CV, Cervelo R3, Giant TCR, Trek Domane SLR, Specialized Allez

User avatar
maverick_1
Posts: 742
Joined: Tue Sep 11, 2007 4:20 pm
Location: Tokyo

by maverick_1

@carlcurry,
Thanks for the feedback.
If I'm not mistaken, the installer actually removed and reinstall the NDS crankarm twice or thrice to get it right during the initial installation, although I wasn't exactly sure the reason behind it.
And no doubt, at this moment the NDS Over Torque arm can be seated by hand easily.
Now, is it possible to claim it under warranty when the root cause is related to an installation issue?

User avatar
alistaird
Posts: 279
Joined: Thu Jul 21, 2016 8:21 pm

by alistaird

maverick_1 wrote:Now, is it possible to claim it under warranty when the root cause is related to an installation issue?


Was it installed at a Campy Pro Shop by a trained installer? The reason I ask is that when I called in at my LBS to have a Record Headset installed, one of the trainees at the LBS was the only one in and he said that if he installed it then it would invalidate the warranty and it had to be one of their trained installers. This was backed up by a couple of other LBS's not being willing to install OT.

Certainly in the UK, your first point of contact with a Warranty claim is with the shop that supplied the goods and not the manufacturer.

Hope that helps?

A

User avatar
maverick_1
Posts: 742
Joined: Tue Sep 11, 2007 4:20 pm
Location: Tokyo

by maverick_1

Guess this is going to be complicated.
OT was purchased in the UK, shipped to Japan and installed at the LBS here in Tokyo.
Mechanic is trained, however I don't think he's trained to perform installation on the OT.
Last edited by maverick_1 on Fri Dec 02, 2016 1:11 am, edited 1 time in total.

User avatar
alistaird
Posts: 279
Joined: Thu Jul 21, 2016 8:21 pm

by alistaird

maverick_1 wrote:Guess this is going to be complicated.
OT was purchased in the US, shipped to Japan and installed at the LBS here in Tokyo.
Mechanic is trained, however I don't think he's trained to perform installation on the OT.


:cry:

Good luck and please let me know (via PM) if you want any more of my limited knowledge.

A

AJS914
Posts: 5397
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

FWIW, Ribble has overtorque crankset for cheap:

http://www.ribblecycles.co.uk/campagnol ... /#pid=5934

User avatar
maverick_1
Posts: 742
Joined: Tue Sep 11, 2007 4:20 pm
Location: Tokyo

by maverick_1

@alistaird
Thanks, will send you a PM if anything.
Hopefully Graeme will share some points and precaution here as well.

@AJS
Thanks for the heads up.
Have actually gotten myself another Comp Ultra with the same configuration.

graeme_f_k
Shop Owner / Manufacturer
Posts: 611
Joined: Mon May 26, 2008 12:21 pm
Location: UK
Contact:

by graeme_f_k

Good evening gentlemen

Apologies, I should turn notifications on, I didn't see the PM hence the slow response (if you PM me and I don't come back to you reasonably quickly, 2 to 3 days, it's always worth dropping me an email direct, as Maverick did on this occasion). When we are busy (and we've been at capacity on technical matters and with service work for about 3 months now, for some reason) I don't get to drift by here so often.

So, Overtorque - the instructions for fitting are OK as far as they go but I guess they don't give the rationale ... basically, the OverTorque fitting is a taper-spline, so the tool is needed to push the crank all the way "up" the spline, where it is mainly retained, if all is well, by the fact that it is a taper system, like a square taper crank.

In a normal scenario, the tool will need around 40nm of torque applied to generate sufficient compression to push the crank far enough up the splines to generate enough interference that it should not be able to migrate back down the splines.

In point of fact, once the end of the axle is flush with the floor of the recess in the crank, the tool can't drive the crank any further "on" as the end of the tool bottoms out against the end of the spindle.

The "screwdriver rock test" is there to check that the crank is fully engaged. It can't be overtightened as such but one can envision a case where it isn't far enough up the splines - say a spindle at the "big" end of the tolerance range and a crank at the "small" end of the tolerance range.

The lockring needs only 8 nm because most of the heavy lifting, in terms of crank retention, should be being done by the splines. The lockring is there to prevent any possibility of the fact that as when pedalling, an offset load is being applied to the crank (as well as the torque transfer that the crank is there to do), the crank is being "peeled" off the end of the axle - the lockring prevents any movement at all, so the crank can't "walk" off the axle.

In Maverick's case, I can see three possibilities.
1. Undersize axle or oversize crank and the installer not doing as we suggest to the guys to do in the UK ProShops, to tighten the tool to 20 nm, see how far the crank has gone on, then try 30 nm, check again, then try 38 nm and check again. Last do 40 nm and check again. If the tightening torque is in the 38 - 40+ nm range to get correct engagement, OK. If the crank is fully engaged at a lower torque - something is wrong. Reject the chainset and refer to a SC. This is my common-sense approach to a system where if the fitter smashes straight in with 40 nm, because the tool will bottom out *anyway*, the fitter will never know if the crank was fully engaged at a far lower torque on the tool.
2. The crank was fitted at 40 nm but was not fully engaged on the splines. In this case, maybe oversize axle, undersize crank, if the fitter didn't do the screwdriver rock test (or didn't understand it's importance), there would not be enough surface area engaged inside the crank to guarantee retention, even with the lockring. If the tool requires more than 42-44nm to get the crank fully engaged, again, I'd say reject the crank set.
3. Lockring not tight enough. Self explanatory really - if the lockring isn't tightened enough, thinking about how the material of the LH crank "squirms" under torque loading, it'll not be tight enough to resist the tendency for it to be unscrewed, like a LH square taper bolt can be undone by crank material squirm. Then, there's nothing to stop the crank walking off the axle.

Unfortunately, looking at Mavericks images, I'd say that there is a case for a SC to examine the crankset under warranty - it's not repairable (sorry) because I suspect that under torque loading, the splines have deformed & stretched / lost material and once that has happened, just like the parallel situation with the burring of the broaching in a square taper, the crank will never stay tight. This will be the reason why you can now push the crank into full engagement (beyond, in fact) without the tool.

I've fitted quite a few OTs and have one on one of my own bikes. For me, if we *have* to have PF, it's a great design but it does need the operative fitting it to really understand what they are doing and the tolerances that it has to be made to are pretty fine, so there is the possibility of rejection of the unit at fitting ... it's the usual problem, the tolerances could be absolutely guaranteed - but probably not at the price-point. It's avery good design but I'd argue it needs too much accuracy for a bulk-production unit. There are ways around that limitation that don't cost so much to impliment, it's true - but all of the ones I can think of mean making the crank deeper at the point of attachment and so either the ankle clearance will be compromised, or the Q factor will increase - and currently Campagnolo have one of the narrowest Qs and one of the biggest ankle clearances out there, and within 2 mm, it's the same on every crankset and they don't want to compromise that.

Manufacture of OT is currently suspended and there is almost no stock of the cranks in Italy, so I suspect that all warranty replacements will be done with Super Record or Record UT (depending on what OY model you have) and PF adapters, for the forseeable future.

HTH
GFK
A Tech-Reps work is never done ...
Head Tech, Campagnolo main UK ASC
Pls contact via velotechcycling"at"aim"dot"com, not PM, for a quicker answer. Thanks!

User avatar
maverick_1
Posts: 742
Joined: Tue Sep 11, 2007 4:20 pm
Location: Tokyo

by maverick_1

@Graeme,

Many thanks for sharing your views on this, most appreciated.
From your explanation above, apart from installation, it looks like manufacturing process could also be one of the root cause why it failed.
Will be sending the crankset to Campagnolo Japan SC for further investigation.

Thanks again!

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
corky
Posts: 1732
Joined: Thu Jul 06, 2006 5:53 pm
Location: The Surrey Hills

by corky

Graeme, Campagnolo should get you to write the English installation instructions for their products.....

Post Reply