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A Man Of The Truth
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Discussion Starter #1
This is a ~1 year old M8100 XT 12 speed rear derailer, with about 1,880 miles on it (thanks Strava).

So a couple of weeks ago, the clutch mechanism seized up. The band was bone dry, so I reapplied some fresh grease and now it works great. EXCEPT....

The lever that activates the clutch will not stay in the 'on' position. I've taken it apart several times, tried every possible position, looked up assembly manuals and verified that I'm assembling it the right way. But still, nada.

Normally when you flip the lever all the way to the on position, it gets into a zone where theres no more tension, so it sort of locks into place. But mine no longer does that. It's continuous pressure on the lever. So after literally less than 5 minutes of riding, the lever completely pushes itself back to the open position. I've looked and looked and I cannot figure out what is going on for the life of me. Hopefully someone here can see something wrong?

I took a pic with the lever in the on position, the off position, and a little video of me flipping the lever. You can't really "see" the tension on the lever, but you can kind of see the way it doesn't kind of 'snap' into locked position.

engaged.jpg

disengaged.jpg

 

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With the cover removed, actuate the lever and take note of the cam position.

Does it appear to be working properly? Or do you know how it should look? If no, of course you don't know if it's working properly then.

Other thing I can think of is the tension is too low, not allowing the cam to stay engaged as there is no pressure.

That's about all I can think of.
 

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I've had the same thing happen a couple of times... it seems that they are really finicky when worn. You can purchase a replacement clutch, but that's not something I care to do on an aged der.

If you just want to make it work, engage clutch and throw a bead of caulk under the lever to glue it into place. It's worked perfectly for a few hundred hard miles until I got around to replacing it and it's is still hanging around as a backup.
 

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A Man Of The Truth
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Discussion Starter #5
With the cover removed, actuate the lever and take note of the cam position.

Does it appear to be working properly? Or do you know how it should look? If no, of course you don't know if it's working properly then.

Other thing I can think of is the tension is too low, not allowing the cam to stay engaged as there is no pressure.

That's about all I can think of.

I posted video. It seems to match all of the service manuals and diagrams and how-to's I've seen. I don't know exactly what the mechanism is that is supposed to keep it engaged, so I don't really know what is causing it to not engage. All I know it is doesn't "lock" at all and it easily, rapidly slides off. And I have it as tight as I can get it.
 

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A Man Of The Truth
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Discussion Starter #7
I've had the same thing happen a couple of times... it seems that they are really finicky when worn. You can purchase a replacement clutch, but that's not something I care to do on an aged der.

If you just want to make it work, engage clutch and throw a bead of caulk under the lever to glue it into place. It's worked perfectly for a few hundred hard miles until I got around to replacing it and it's is still hanging around as a backup.
I'd be hesitant to buy a new clutch only because this one was working perfectly until i disassembled it for the other seizing issues. So I'd be afraid a new clutch would have the same problem, like maybe it is somehow an assembly issue that i'm not seeing?

Also I've thought about trying to throw a zip tie around the lever to keep it on. I may yet do that, or something along those lines.
 

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I don't know exactly what the mechanism is that is supposed to keep it engaged, so I don't really know what is causing it to not engage.
There is a cam on the post that rotates with the lever.

Perhaps it is an issue with the orientation of the spring, that cam, or the outer plate that ties it together... but I spent hours trying to figure it out, taking apart two derailleurs and swapping parts, only to have the same issue. I tried all kinds of stuff like bending the spring in an attempt to get friction on the cam etc.

If you do figure it out, please post your findings.
 

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Magically Delicious
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Let's go back to here...

So a couple of weeks ago, the clutch mechanism seized up. The band was bone dry, so I reapplied some fresh grease and now it works great.
What did you do to service the Chain Stabilizer (roller clutch and clutch band)?
 

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A Man Of The Truth
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Discussion Starter #11
What did you do to service the Chain Stabilizer (roller clutch and clutch band)?
I reapplied some fresh grease where the band and cam come in contact. That part of the mechanism now works normally. I've tried the little activation cam in every orientation possible. It either does nothing, or it adds pressures but has no "locking" in to place. Very annoying.
 

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A Man Of The Truth
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Discussion Starter #12
So I stuck a small zip tie through one of the holes in the body to try to hold the lever in place. Unfortunately it doesn't really put the pressure in the right direction. So it will prevent it from fully disengaging but I don't think it will actually keep it fully engaged. Tuesday is 6 hour bike ride day so by tonight, I'll know for sure one way or the other.
 

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Any news regarding your problem?
I've exactly the same problem with my SLX m7100. Since opening the clutch it will no longer stay in ON position. It was working fine before that.

If I put clutch in ON position and move the cage a few times it will slowly move to OFF. Just like on your video.

I've disassembled the clutch a million times but cannot find out where is the problem. I also doubt that new clutch mechanism will help.
It is assembled properly and I've tried all possible tension options, but it will not work...
 

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A Man Of The Truth
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Discussion Starter #14
Sadly no. I currently have my lever zip tied to the ON position and it still doesn't work very well. I went to order a new (SLX) derailer but suddenly everyone is out of stock. So I'm just clunking along for now.
 

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Clutch solutions?

I'm having the same issue as the OP (and several others): after less than 2,000 miles my XT 8100 derailleur cage stopped tensioning the chain when shifting to smaller cogs, which made it unrideable as the chain would swoop down and I'd get dropped chains constantly. General maintenance including greasing the clutch mechanism fixed the issue, but now the clutch lever won't stay in place for more than a few minutes. I, too, tried several of the mentioned fixes, including LBS, to no avail.

So my question is, what is the solution? I found a $14 replacement shimano clutch somewhere online, would this do the trick? (obviously far preferable to buying a new derailleur for almost 10X the price...) Or is anyone simply riding 12 speed with the clutch off (and a big fat chainstay protector)? I tried it and definitely do get dropped chains, though it's far from unrideable.

Or do I simply need to buy a new derailleur? I must say I'm disappointed that these shiny expensive engineering marvels are almost disposable... I mean, mine didn't last much more than the stock tires on my new bike. If I were to buy a new derailleur, would moving to Zee or XTR offer better durability in this regard?
 

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Magically Delicious
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For $14, I would consider clutch replacement. What did that $14 replacement include? Was it the Cam Unit (tension cam) and the Chain Stabilizer (clutch band and drum) or just one of these?
 

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I thought of this

I thought of this, but think it doesn't apply in my case. Here's why: when the clutch is engaged, I feel an instant and noticeable "stiffening up" of the derailleur cage, which to me, signals the cam is right way in and the clutch is working. The problem is that the lever won't stay in the "ON" position for more than a few minutes.

Am I right in thinking that cam direction is not the issue here?
 

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I thought of this, but think it doesn't apply in my case. Here's why: when the clutch is engaged, I feel an instant and noticeable "stiffening up" of the derailleur cage, which to me, signals the cam is right way in and the clutch is working. The problem is that the lever won't stay in the "ON" position for more than a few minutes.

Am I right in thinking that cam direction is not the issue here?
Sounds like the cam isn't oriented correctly to me. If it isn't oriented correctly it won't keep the pressure on it to keep it in place. It takes about five minutes to check to know for sure.
 

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Magically Delicious
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The Tension cam is correctly installed. All you have to do is look at the drum band close when ON (counterclockwise/up)
 
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