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Discussion Starter · #1 ·
I thought I would have no problem with this setup on my singlespeed. Especially liked the fact that the Dura-ace bottom bracket weighed 40 grams less than the XTR!
The spindle length was okay for my chainline and It seemed like the spline interface was good enough. I had some issues with loosening crank bolts, and now the drive side crank arm is loose on the splines.
Has anyone else had a problem with these two components mating? Did I just ride a little too long with loose crank bolts?
I am replacing the XTR 950 cranks with some 952s. Do you think I will have the same problem?
Also, I noticed the XTR 950 bottom bracket is lighter than the 952. Anyone aware of the difference? Do you know where I could get my hands on a 950 with a 112.5 spindle?
 

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schnapmaster said:
I thought I would have no problem with this setup on my singlespeed. Especially liked the fact that the Dura-ace bottom bracket weighed 40 grams less than the XTR!
The spindle length was okay for my chainline and It seemed like the spline interface was good enough. I had some issues with loosening crank bolts, and now the drive side crank arm is loose on the splines.
Has anyone else had a problem with these two components mating? Did I just ride a little too long with loose crank bolts?
I am replacing the XTR 950 cranks with some 952s. Do you think I will have the same problem?
Also, I noticed the XTR 950 bottom bracket is lighter than the 952. Anyone aware of the difference? Do you know where I could get my hands on a 950 with a 112.5 spindle?
Loose crank on splines can cause the interface or splines on the crank to wear since they are a little soft anyhow, and thus you may need to replace the crank arm. At a race, I rode my cranks, and at the end they were loose - the race was a few days in length and I never remember checking my cranks when I checked everything else.. I ended up having to replace a crank arm because of that.
 

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The Dura Ace BB is only meant to be run on 68 bb shells. Like on a road bike. When you put the spacers on the bb to widen the cups to a 73 width. The ones that come with the XT bb. You comprimse the spacer that is on the dura ace BB. I am pretty sure that the dura ace BB is not meant to handle the extra force of the wider spindle length on the XT.
 

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Discussion Starter · #4 ·
Let me clarify

Thanks for the ideas, but I guess what I am asking is if anyone is running a dura-ace bottom bracket with xtr cranks and having longterm success.
I realize that it is for a 68mm bottom bracket shell. That is the width of the shell on my mountain bike.
I know that I need to replace the arm that has a loose spline interface. I also realize that this whole problem may have been caused by loose crank bolts.
The reason I suspect the dura-ace/xtr spline interface is that when you first crank the arm onto the bottom bracket, there is a little of the aluminum spline on the crank that gets scraped off.
I know other people have tried this combo, so how did it go for you?
I have just bought a new set of xtr crank arms. If the demise of my last ones was caused by loose bolts, then I will use the new xtr cranks with the dura-ace bottom bracket and pay close attention to the bolt tension. If others tell me they think that it is a compatibility issue, then I will just use the xtr bottom bracket and not risk using the dura-ace.
 

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If you're not using a...

torque wrench you really NEED to use one with 950/952 XTR cranks. The Dura-Ace BB and the 950 BB are exactly the same BB as a matter of fact. The only difference is the spindle length and ability to run 73mm with the 950. They have exactly the same spline system and internal design. The difference between the 950 and 952 is that the 952 is fully sealed and non serviceable. It wears out and you throw it away.You're problem with the loose crank was likely caused by the spines on the arm not engaging fully on the BB. Setup of this type of crank is very finicky as the contact area of the spline is VERY small. It takes a lot of torque to seat them in all the way. Many people damage them because they feel fully seated and like the bolt is about to pop when they still need several more turns of the bolt to go all the way in. The only way to be completely sure is using a torque wrench and torque them down to the recommended pressure.
 
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