[skxskibum]

earlier this summer i tore up the bearings in my campy chorus ultra-torque crack. I have reinstalled several bearings and have tore up each successive set of I've installed. If I tighten the bearings to where there is no play between drive and non-drive sides, I crush bearings. If I torque the bolts to the recommended value 33.19ft-lb the bearings get curshed and bind. Help, what I am doing wrong?

The bike 2003 Tomassini, new chorus cups, campy bearings; Chorus, carbon, ultra-torque crank

 

[spookyload]

Sounds like your BB isn't withing the specs of Campys range. May be too wide and causing a problem. You need to measure it to make sure it isn't out of the limits.

 

[C-40]

advice...

There should never be any bearing problems if you follow all of the instructions. First, the BB shell width must be 69.2-70.8mm. If you have not verified that, then the problem may be obvious. If the BB shell is too wide, the wave washer will apply too much preload to the bearings.

Have you always used the same cups? It is possible that they could have have been machined to the wrong width. Cups are relatively cheap to replace.

The BB faces must also be square to the threads. I check that by tightening the BB cups until it just touches a .010 inch feeler gage, placed between the cup and BB shell. I then use .008-.012 inch feelers to search for high or low spots. If any are found, the BB shell needs facing and then remeasured for proper width.

If all that is done, all you do is grease the threads and torque the cups to 35Nm. Install the crankarms and tighten the center fixing bolt to 42Nm. Don't forget the retainer clip on the right side cup.

Last, there is always the chance of a defective crank, machined such that the distance between the bearings is wrong. One way to check this would be to install the crankarms without the wave washer. Without the wave washer, there should be axial movment in the range of about .8-2.4mm. Any less and something is wrong.

I have to assume that you know how to properly install the bearings so they are seated against the faces of the spindle and you are using the proper 6mm width bearings, not 7mm width bearings.

 

[skxskibum]

thanks for the reply

The bottom bracket shell is within spec's as I measured it when I bought the cranks years ago. It is only this summer that I have had problems, it seems that if I torque to the recommended values given in the campy instructions the bearings are way to tight. I have a good (Snap On) torque wrench that should be fairly close to calibrated. In order to ride the bike again, what I have done now is guess at a torque value which is way below the range of my torque wrench to where the play between the drive and non-drive side is gone and the bearings still run free

With respect to the bearings, I made the 6mm/7mm mistake early on but I've been using campy bearings.


Thanks for help

 

[frdfandc]

How low does your Snapon torque wrench go to?

 

[skxskibum]

its the big 1/2 inch drive, so 30ft-lbs. I think if there's a problem it would because the value I need is almost out of the range of tool, but I would not think the torque value would be that far off. Problems like this are reasons to buy tools, so I am thinking about a 3/8 inch drive that would have the proper range

 

[frdfandc]

Even a Snap on 1/2 inch at the lowest setting is not 100% accurate. Its actually overkill. When Snap on calibrates their torque wrenches, they start at 100 ft/lbs and go up. At least that is what I was told by my Snap On tool guy last year when I had mine checked. They have a limit of 2% +/- at 200 ft/lbs.

Get the correct range torque wrench. That will help out with getting the correct torque spec.

 

[skxskibum]

yup doing just that, I have 1/4 inch and 1/2 inch but not the 3/8 and I'm going ride my guess

 

[C-40]

bad idea...

Using reduced torque is the wrong solution to your problem. The torque applied to the center fixing bolt must be about 42Nm to work properly and stay tightened. You're likely to have the bolt loosen and fall out during a ride.

You have some other obvious problem. The cups are bad or you have not installed the bearings properly. What's happening is the wave washer is being totally crushed and binding up the bearings. The wave washer is about 3mm tall when it's in the free state. When the center fixing bolt is tightened, there should never be less than .8mm of space for the washer and preferably more.

I assume that you have not used any spacing washers under the right cup to correct a chainline problem. You can't do that with a UT crank.

Another possible problem is not torqueing the cups to 35Nm. The cups must be firmly seated against the BB shell or the width might be too great.

I'd try some new cups and recheck the bearings for proper seating on the spindle.

 

[natedg200202]

skxskibum, Did your problems start when you replaced the bearings? In other words, did you have problems with the original bearings that came with the cranks?

C-40 is giving good analysis. I just wonder if the replacement bearings are the correct width?

Good Luck!