My bike has a set of ultra torque cranks which has that single bolt deep in the middle holding them together. Is that bolt a 1 time use that I should replace if I decide to remove the cranks (say for cleaning)? I found the bolt online for about $30.

These cranks have been installed for about 5 years, and I'm not sure its "that" dirty down there, but just in case.

The only one-time use bolts I am aware of are on aircraft engines and (I think) Mercedes-Benz connecting rod bolts.

That bolt can be reused pretty much as often as you want to. When opening up an Ultratorque crank, pay particular attention to the spring clip on the drive side cup, you will see it just behind the crank. It is absolutely needed for the cranks to work properly. When removing the cranks, remove the clip before you remove the centre bolt. When you reinstall, install the drive side crank, then put the clip into place, making sure that the clip fits fully into the small holes on bottom bracket cup. This can be tricky because you have to work behind the drive side chainrings. Once the cup is in place, you can install the non drive side crank arm and then tighten the centre bolt. With practice, installation only takes about 5 minutes

Theres actually a lot of automotive bolts that are one time use, like many cylinder head bolts (especially VW/Audi), some brake caliper bolts, and some others.

Awesome thanks for the tips. I remember from building it that clip was a PITA, and I recall theres like a wobbly washer inside the bearing cup I need to make sure stays there right? Thanks again

I've been out of the auto wrenching biz since the '70s so thanks for the updated information. Cars used to have things called "distributors" and "carburetors"....

A little trick when you are installing an Ultratorque crank: Before you put the driveside crank into the bottom bracket cup, push the clip so that it is almost ready to slip into place, then push the drive side crank into the cup. Then all you have to do is to push the clip the last mm or so to where the ends of the clip snap into those tiny holes. After you have done it a few times, it is easy. It took me about 10 times before it became easy for me. A company other than Campagnolo, less focussed on appearance would have put that clip on the non drive side
I have installed dozens of Ultratorque cranks, so what seems easy for me may well seem difficult for someone who has only done a couple

Thats a good idea thanks for the tip, I will give it a shot. I do love the way it looks and always get compliments from other riders, so maybe its worth it for the looks. Thanks again!

It's a normal bolt. Just be sure to tighten to the proper torque.

One thing about that - you should have the proper tool which doesn't look much like a tool at all. It has the proper size on one end and then increases to a larger size all the way to the outside of the crank. I believe you supposed to set the torque on that bolt to 29 ft/lbs.

Yes it take a bit of torque, 40 Nm IIRC. That driver head to get at it is expensive but worth it