Breaking Ultra-torque hirth coupling bolts - help

[winkybiker]

I have three times now broken the bolt that holds the two halves of a Campy 10 speed Record UT BB spindle together. It's the little squat bolt (15mm) that resides deep inside the spindle. (Campy part# FC-RE007).

All on the same frame (BMC Pro-machine about 6 years old). The first one broke two years ago, then last year then yesterday. They're properly torqued, and I'm not an especially big or powerful guy.

The BB otherwise runs fine. Smooth, quiet and only just needed a new set of bearings after 6 years.

I don't know anybody else who has broken even one. What might be going on? Any ideas?

 

[ElChingon]

I could only imagine the cups or the BB is not aligned right which causes added stress on the bolt, or the BB is broken (BB shell). Or you just happen to get the defective batch of bolts. I have only had one bolt loosen on me, till I lock-tightened it to death, well just added enough but you get the picture.

 

[winkybiker]

I could only imagine the cups or the BB is not aligned right which causes added stress on the bolt, or the BB is broken (BB shell). Or you just happen to get the defective batch of bolts. I have only had one bolt loosen on me, till I lock-tightened it to death, well just added enough but you get the picture.

That's what I getting checked. Alignment, dimensions and structural integrity of the BB. Thanks.

 

[Bustedknuckle]

I have three times now broken the bolt that holds the two halves of a Campy 10 speed Record UT BB spindle together. It's the little squat bolt (15mm) that resides deep inside the spindle. (Campy part# FC-RE007).

All on the same frame (BMC Pro-machine about 6 years old). The first one broke two years ago, then last year then yesterday. They're properly torqued, and I'm not an especially big or powerful guy.

The BB otherwise runs fine. Smooth, quiet and only just needed a new set of bearings after 6 years.

I don't know anybody else who has broken even one. What might be going on? Any ideas?

Never seen one broken. I suspect there is some sort of side load on the spindle or other misalignment. It isn't an oversized, too wide BB shell, otherwise the crank would bind, not turn...Are the hirth 'teeth' damaged or gooned up?

Are you in the US? Call Dan Large at Campagnolo, NA.

 

[winkybiker]

Never seen one broken. I suspect there is some sort of side load on the spindle or other misalignment. It isn't an oversized, too wide BB shell, otherwise the crank would bind, not turn...Are the hirth 'teeth' damaged or gooned up?

Are you in the US? Call Dan Large at Campagnolo, NA.

The "too wide" possibility was discussed with the mechanic and discounted exactly as you have said. It's going in to the shop this week for them to check it over. Teeth looked OK last time, but that will be looked at. I have another crankset that I might just put in on suspiscion. Thanks.

Nice to know that it is vanishingly rare (except for me ), so should be able to be fixed for good.