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Discussion Starter #1
Noticed I had a bit of side to side play in my crankset (XT 12spd) the other day. It was only 1-2mm so hopefully the crankset isn't trash. How often should I be checking the pinch bolt torque on these cranks? Also, if the cranks do start working themselves loose soon (they're damaged), do I need to replace the entire crankset or is it usually just the left crank arm that's toast?
 

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I never had a Shimano crank arm come loose. You should be fine if it was loose for a little while. Square taper had an issue with that but I don't think it will be a problem with a spline like interface and pinch bolts.

Pinch bolts installed with blue thread lock and a good torque wrench. Evenly tighten them up to torque spec then when one clicks go back and forth between them until they both click without turning.

Can obviously be done great without a torque wrench but that depends on how good you are at feeling the bolt stretch so you don't over or under tighten.
 

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So for sure it was loose pinch bolts causing the side play? IME that's unusual, once torqued I never check mine and rarely see loose ones causing bb play when doing repairs.

If the bike was ridden for long with them loose it's possible that damage was done but I'd try torqueing everything up and see what happens.
 

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Happened on my Buddy's SLX crankset after around two years. He didn't fit the cranks or ever check them. If the worse happens it will only usually be the crank arm interface that strips and not the spindle/Cranks. He replaced the arm and was all good again.
 

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Discussion Starter #5
So for sure it was loose pinch bolts causing the side play? IME that's unusual, once torqued I never check mine and rarely see loose ones causing bb play when doing repairs.

If the bike was ridden for long with them loose it's possible that damage was done but I'd try torqueing everything up and see what happens.
I'm pretty sure. The bolts weren't as tight as I felt they should be (couldn't check torque mid ride). When I got home I took them apart, cleaned and regreased them. I used a torque wrench and blue locktight on the pinch bolts. Everything feels smooth and the bike is only 7 months old so I don't think it was bearing wear.

Part of my concern is I've seen someone's XT crank arm fall off in the middle of a jump line (thankfully a tame jump line). I know he already had issues with it coming loose and tightened the pinch bolts a few runs before. I know if it gets to the point you're tightening them midride not hit jumps but it made me wonder how often I should be checking the pinch bolts and what others experience is.
 

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same as most replies, I just torque those down once on install and they've never needed attention after many months of hard riding and rock strikes. one and done in my experience....lawyer tabs or not, stays put. blue loctite, correct torque works for me
 

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If it continues to come loose you will have to replace the NDS crank arm. It's an aluminum crank attached to a steel spindle, the steel component will always win.

I've broken Shimano crank arms, but it's very uncommon. I agree that they should stay put once properly installed.
 

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Discussion Starter #8
If it continues to come loose you will have to replace the NDS crank arm. It's an aluminum crank attached to a steel spindle, the steel component will always win.
Ok good because honestly I'm going to buy another full XT crankset if the spindle ends up being toast.
 

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Torque properly those should never come loose.

Make sure you check the torque on each bolt a couple of times. With that system you can't just tighten one bolt then the other and call it done. You have gradually increase the torque on each bolt, alternating between them as you do it.
 

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I have bikes with 1000s of miles that have been a one-and-done. And I have a bike with SLX that likes to get loose every once in a while. Once re-assembled and torqued it is always fine until it isn't again. I've never tried locktite but I will now.
 

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Just a note to all: Use the BLUE LocTite. Just a couple drops at most is sufficient. (y)
 
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