Campagnolo Over Torque Left Crankarm fell off

[maverick_1]

@corky
+1 on Graeme's clear instructions/explanation.

@Juanmoretime
Noted, good advice! Will do that next time!

[mortirolo]

Anyway, was on my regular route yesterday, mid way through the ride I realized something wasn't right with the left pedal and that was when I found out that the Over Torque left crankarm was totally detached from the main axle, leaving it dangling on my shoe.

Situation:
Crankset has approx 2500-3000km in total mileage, was installed professionally by my LBS.
I'm assuming the problem could be related to abnormal wear on the left crankarm, however I'm not exactly sure.
Currently, it seems only minimal force is required to slot the left crankarm to the main axle (you can even slot the left crankarm using your bare hands)
When using the UT-FC220 tool and tightening it to 40Nm, the left arm will move beyond the main axle.

Campy states "Using a flat screwdriver, ensure that there is no 'step' between the axle and left arms"

2. What is the main purpose of the "Closing ring nut" with a tightening torque between 8-10Nm?

Instructions as per Campagnolo:
035_28_Technical manual - over torque crankset - Campagnolo_Rev03_02_15

My situation is mostly same but the "abnormal wear" is far less, I mean:
I can even slot the left crankarm using my bare hands, but luckily
there is no 'step' between the axle and left arms.

My left crankarm was totally detached from the main axle on my not regular training route, I mean on Stelvio in Italy.
So I descending back to Bormio.
Luckily I found a real MAESTRO in a local bikeshop.
He told me the campagnolo over-torque system is a crap.
(I am a campy fan, but mechanical engineer too..., so He's right.)

He put some green loctite to the threads of axle and closing ring nut.
The closing ring is alu, so You can't use more Nm than the offered 8-10.

It's not the perfect solution, but it was 11 months ago and left crank is still on the axle.

My opinion:
A longer thread inside the axle would be a better solution and/or a titanium closing ring.

My second problem:

I can't use gaskets (external seals), because there are not enough space.
I have an AX Vial.
It has integrated BB with technicaly same parameters as a 386EVO.

I measured the installed bearings outside to outside.
It must be 86.5+-0.5 by Campagnolo technical manuals.
So the 86.35mm (86.5-0.15) is inside the tolerance.

In my opinion in dry conditions the external seals could be left,
but It's less ideal with my NTNs (non contact, steel races, steel balls, steel cage).
Cult bearings won’t be available for it, so the USB bearing (stainless steel + ceramic) will be my next upgrade.