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How well should my Dura-Ace Bottom Bracket spin?(7 posts)

How well should my Dura-Ace Bottom Bracket spin?glia
Dec 24, 2003 8:16 PM
Just finished rebuilding my Dura-Ace BB which after only 4000 miles (nice weather miles!) started grinding. I cleaned each ball and roller individually and packed it well with Park's Grease. Now it has no noised and no noticable play and I assume it is working well again. However, when I compare it to the Ultegra BB on my second bike the Dura-Ace turns a lot harder no matter how I adjust it. Now when I say a lot harder I may need to qualify. When I spin either crank without chain on it, the Ultegra will do 2-3 full turns before it stops. The same push will move the Dura-Ace only 0.5 turns. Is this an issue? Should I scrap that Dura-Ace and install another Ultegra? Is there any inhert adavantage other than the 50g weight savings that suggests to stick with a Dura-Ace? Thanks for your advice.
re: How well should my Dura-Ace Bottom Bracket spin?crankset
Dec 24, 2003 8:31 PM
Hi glia. Try this, I had the same problem a few weeks ago. What was happening was that the bearings were binding after adjusting them. Basically all you have to do after you adjust them, install the cranks and hit the cranks horizontally at the bottom bracket to force the bearings to seat. If you get feel play and the crank turns much better, that is your problem. I used a rubber mallet to hit the crank. I guess you can do it with your hand too, it doesn't take much.

After that, readjust the BB and it should spin much better. It probably still won't spin as well as the Ultegra, mine didn't but it got much better. Maybe after some riding it will get better. Did you by any chance install the BB on a different frame or is it the same frame? Was it hard to drive the cups in the BB? The bearings on the Dura Ace ride against the cups and if the BB is a little tight as far as circumference, the bearings get bound up.

When I had mine binding it was only going .25 or less of a turn. Hope this helps.
re: How well should my Dura-Ace Bottom Bracket spin?glia
Dec 25, 2003 8:34 AM
Thanks crankset. Your suggestion improved the spin. As you said, it is still not quite as free as the Ultegra but certainly an improvement. So what does it all mean. Does the Dura-Ace BB have an inherently greater friction? If so is that due to more bearrings? Does it matter?
re: How well should my Dura-Ace Bottom Bracket spin?curlybike
Dec 25, 2003 9:07 AM
I have run ito the circumstance several times and it is usually caused by one or more reasons:
1: The threads in the bb shell are not on the same axis and this is causing the roller bearings in the BB cups to try to bend the spindle as it passes through them. Attempting to bend it into a shallow U, so to speak. This can be improved by having the LBS tap the BB shell with Campy taps that are tied together by a beefy center guide. Also the BB shell should be faced after the bb threads are tapped. This should improve the problem somewhat.
2: The bb threads are on axis, but are distorted or too tight, the distortion occurs when the pre-threaded bb shell has the rest of the tubing welded to it. The builder frequently omits the Re-tapping of the shell or does not go as deep as the Shimano threads extend into the shell. This too may be improved by retapping. I had one frame that required that I remove the first several threads from the bearing cup of the bb and loosen the threads on the cup by turning the cup in a lathe and filing the threads with a 3 cornered file down in the thread form.
Hope this explains a little.
Also check the wear pattern on spindle of the bb and if it is not a full roller wide on each end, the skewed bearing cups are your problem. Look for flaking on the surface of the spindle with a magnifier. If you have it, chuck the whole thing and replace it with an Ultegra.
re: How well should my Dura-Ace Bottom Bracket spin?crankset
Dec 25, 2003 11:04 PM
I don't know the answer to that one but my feeling is that Dura Ace needs a perfectly cut BB or this will happen. That's just a guess, I don't know. I would go with what curlybike said, ride the bike and see if it improves, if it doesn't, go with Ultegra. That's what I'm doing. As a matter of fact I tried an Ultegra type BB on the frame I had the problem and it worked without binding. It was a Campy so I couldn't use it with the cranks but it goes to show you that if things don't improve with the Dura Ace, maybe the best thing is to go with the Ultegra and forget it.

I tried the Dura Ace BB with other frames and it was fine. That's why I'm guessing it has to do more with the frame than with the BB itself.
It could just be the new greaseKerry Irons
Dec 26, 2003 4:50 PM
Depending on how stiff the Park grease is, it might just take some time for the grease to "oil" and for the extra stuff to get pushed out of the way.
It could just be the new grease...I second that !!!WiseGuy
Dec 29, 2003 8:06 AM
I use both Ultegra and Dura Ace bottom brackets on my road bikes and I found that the DuraAce initially has a little more drag when set up correctly. Within a very short time (a couple of rides) however, the whole thing seems to loosen up as the grease gets worked in and the free spin becomes sweet.