What caused the tabs to break off Campag free hub?

[wilwil]

Put my just cleaned 12speed cassette back on my Bora WTO wheel and as I was tightening the lock ring there was a cracking noise, tightened a bit further and a whole load of cracking noises. All the tabs at the back of the free hub had broken off. These are the spacer tabs that stop the cassette from touching the wheel. I was not near the 40nm spec. I'm assuming I've done something wrong but can't think what as I've installed cassettes countless times. It's happened before on a CK hub because I put a small spacer behind the cassette, something I won't do again.

[Bobbyc123]

That's happened to me before, with two tabs cracking clean off and always got issues with premature wear on the freehub bearings.

Couldn't work out what the issue was, only explanation mechanic could think of was possible under tightening.

[tjvirden]

Any chance of a close-up photo?

[wilwil]

Here are some pictures. Sorry I don't have the tabs that broke off. You can see the broken areas directly in front of the blue plastic flange.
The outer bearings don't seem to last that long but can be replaced.

[c60rider]

That seems almost unbelievable, there must be a fault with the body somewhere. I've always tightened the lockring by feel in years gone by as I never had a torque wrench. However when I did get some proper wrenches I couldn't believe how much tighter the torque setting took it. So I went back to feel and yet still that stupid 2.3mm spacer ends up breaking eventually. I thought they'd break even quicker going by the recommended torque.

[ohexploitable]

wow you'd think that the threads on the aluminium lockring would give-in first

[wilwil]

There's only one way to install the cassette but I'm wondering if somehow things weren't seated correctly when I started to tighten.

C60rider, they've done away with those brown plastic spacers on 12 speed they are all aluminium now.

Maybe GFK has an answer?

[smokva]

I had exactly the same fault few years ago when one tab broke....I wouldn't even notice it but shifting became bad so when inspecting everything I was surprised to see this.
I think this is due to few factors:
1. Material choosen to make body light and machining it to make bits instead one whole ring
2. Overtightening or undertightening of cassette. It's even possible to have local overtightening on one or few bits.
3. Cyclical stress on the machined sharp corner from where fault propagates until bit cracks off.

Campagnolos HG (shimano) bodies are actually much stronger since they are made from steel instead of alu which is used for campa compatible bodies.

[tjvirden]

Perfect photos.

There are lot of aluminium freehub bodies in the world and this is surely incredibly unusual! I really can't think you could have "done anything wrong" to make this happen. The transition from tab to spline looks to have been relieved (by a carefully machined slot) properly, so normal stresses shouldn't have started a crack there. Even tightening the lockring to 50Nm should never result in this.

I wonder if it might have been caused by improper alloy specification or poor/missing heat treatment, in combination with a form of corrosion. There's not really much cyclic loading in the direction along the splines so the problem would take a long time to appear.

All very odd!

[rudye9mr]

What is the cleaning protocol and degreasers/ detergents used?

[wilwil]

What is the cleaning protocol and degreasers/ detergents used?

I dont spray the freehub with any degreasers it just gets a wipe with a dry soft cloth and maybe a baby wipe, after I remove the cassette. I use Morgan Blue chain cleaner and clean chain on the bike so that could have crept down there. The wheels and gruppo are about two years old and not used in winter. The cassette is the same one from new and I'm half way through my second chain. Its not the first time I've removed this cassette for cleaning. I use Smoove lube.

I noticed on the replacement freehub that they are now made in Taiwan.

[smokva]

Just for reference...this is from RBR forum few years back:
https://www.roadbikereview.com/threads/ ... ub.350315/

[Geoff]

That is unreal. I have never seen anything like it before, myself. I took a look at some of my Campagnolo freehubs over the years and they show absolutely no signs of similar stresses (admittedly, I am 60kg and only produce 1,200 watts). That same basic design has been in-service for a lot of years so I am surprised to see that. Please keep us informed of what Campagnolo says.

[tjvirden]

Just for reference...this is from RBR forum few years back:
https://www.roadbikereview.com/threads/ ... ub.350315/

Well spotted. I think that explains the problem - a badly made batch of them in circulation.

[gipogipo]

Today I noticed the same broken tabs on my fulcrum racing 1 freehub body - which I believe is the same found on campy wheels.
I always torque the (lightly greased) lock-ring at about 30Nm, so I don't think it it could be an overtightening issue, more probably something connected with material fatigue and repeated stress.
Luckily I had only 2 broken tabs, my sprockets are turning only a little bit out of true, with no impact on shifting: can I safely use that wheel again?