Campagnolo Power Torque installation - spring and gasket order
 

Hello!

Every now and then, when servicing, re-ordering or building a new bike I always end up wondering about the same thing. What order should the NDS spring and gasket be in when installing a Power Torque crankset? What Campagnolo shows on their instructions just doesn't make any sense to me; the logic way should be that the plastic dust cover (namned "gasket" by Campagnolo) should cover the bearing on the inside, not be faced towards the crank arm? What good does the wavy spring to protect the bearings? :foo:

Anyone has similar thoughts, or can explain to me the idea behind this set up?

Cheers,
Gustav



https://cimg8.ibsrv.net/gimg/bikefor...991fe63965.jpg

Note: Park Tools show the spring on the outside at this crank service instruction:

(Figure7)
https://www.parktool.com/blog/repair...o-power-torque

Best regards,
Confused

I've assembled two and if I understand your point correctly it did not occur to me. The bearings were sealed bearings which looked like typical buna-rubber so I just assumed the spring kept the bearing located correctly and the gasket was to prevent the metal to metal or metal contact with the crank arm or metal to carbon contact with a carbon crank arm.

The Campy video shows the spring going on first up against the bearing, then the sealing gasket, starting at around 1:10.

The diagram above is not from the assembly instructions, as such - it looks like the type of schematic that Campagnolo sometimes use during training courses at the factory.
This one, IIRC, was used to show the overall assembly plan - you can actually just see behind the seal / gasket (translation varies ...) coloured in blue, the spring, coloured in yellow / gold ... in this view, because it's not intended as an assembly instruction, it's shown as in contact with & "behind" the seal.

The best source of info to see the correct assembly sequence is either one of the Campagnolo-produced videos at www.campagnolo.com (or on the Campagnolo YouTube channel) or to look at the exploded diagrams under "Spare Parts", also at www.campagnolo.com.

I've never really understood why people don't go *first* to the manufacturer's website or email Campagnolo for advice ... they make the product, after all!

Here you can see the correct assembly order (this is from the Spare Parts section at www.campagnolo.com):

https://cimg7.ibsrv.net/gimg/bikefor...76e18d910f.gif

As you can see the seal (gasket) sits over the spring, so that the spring sits entirely within the BB cup and the seal lip meets the edges of the cup.
The only criticism I have of this exploded view is that it doesn't show the washer that sits between the axle end bolt and the BB spindle as a separate part (which it is) so unless mechanics look at the video, they might not check that they have removed it, before trying to pull the crank off - which is usually a fatal error, as far as the crank is concerned!

I can't remember the spindle bolt washer specifically but would have surely looked for a washer in that application so probably pulled it out and replaced. How would it be a fatal error if one had left it in the arm?.

I just picket up a couple of these as part of building some touring bikes. In answer to the OP, the wavy spring-steel washer serves to impart a pre-load force onto the sealed bearings. This is done in ball-bearing scenarios to make sure the bearing parts rotate in relation to each other, rather than skidding past. The pre-load should ideally as light as possible, so this spring washer in this set up is not ideal. I substitute some M25x30 washers to get a more subtle preload.

Hope this helps.

The preload washer imparts, when compressed to the degree allowed by the tolerance given for BB shell width, a pre-load in the *correct* range, as specified by Schaeffler, who make the bearing.
It's beyond me why people try to second-guess the people who actually make the assembly and in this case, who specify the bearing and the spring washer that supplies the pre-load specified for the application concerned, by the bearing maker.
Very odd.

Everybody's an engineer on the Internet.