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Discussion Starter · #1 ·
Hi all,

I have suddenly very weak tension on my Sram X9 (3x10 speed, from a 2010 Specialized Stumpjumper Comp), but cannot take apart the body to check the spring.
It seems this version is different from many others I have seen. The thing stopping the tension arm to go around is also not a screw, but the body itself, so I cannot do the hack to just spin it around to increase the tension. I attach the pictures. Any idea how to take the body apart?
Thank you!


 

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Link to repair spring tension.

Hello and a warm welcome to the forum,

Bummer on the spring tension on the Sram derailleur... I've not first hand experience but after researching online I'm not sure which models of Sram derailleurs can be pulled apart to adjust the tension spring or not? Some of the posts stated they cannot be repaired when the spring tension becomes loose and others stated that Sram uses such powerful springs that they seal them so they don't ever need repair in that way?

In any event here was a post made here on MTBR that a fellow poster linked a website that shows how to disassemble and repair spring tension in a Sram XO derailleur:

https://forums.mtbr.com/drivetrain-...s/derailleur-spring-chain-tension-561547.html

Direct link to the possible fix:

https://aubryvg.blogspot.com/2009/10/rd-cage-spring-repair-guide.html

Hope it's this simple for you as well and best regards,
Jason




PS -- Forgot to add one poster had made a repair to their X9 derailleur from the post above:


robc in wi wrote:

"I have an X9 rear that after having the wheels off for transport I had almost zero tension on the chain. Somehow, the cage (or whatever) had slipped past the small metal tab that sets up the tension. Hard to describe but once I wrestled the cage back behind the tab and re-mounted the wheel all was good. This was a nearly brand new rear der. "
 

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Discussion Starter · #3 ·
Thank you Jason!
Unfortunately it seems none of those options work for my derailleur. I wonder if mine is the type that just cannot be taken apart. On the pictures, the U shaped metallic part protruding from the body seems to be the only place it could be dissasembled (no screws or anything other than that, so it seems).
I am hoping someone on the forum has experience with this type and recognizes it from the pics.
Gabor
 

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Discussion Starter · #4 ·
I managed to fix my derailleur since, so wanted to write it down in case someone else has issues with a similar one.

You can see on the picture the U (or D) shaped metal protruding from the body of the derailleur. As there is no screw on the body, after looking online and deciding which new derailleur to buy, I thought I have nothing to lose and pulled that out with force. That's it, the body can be disassembled then and when you are ready to put it back together that little metal/plastic thing can be pushed back whilst holding the body together (against the force of the spring).
Okay, so now I know how to take it apart and put it back together, but still, the spring inside was "jumping", once I started rotating the arm so that I have tension, it did not hold. Taking it apart it was easy to see which end of the spring is not held in space. I made a hack solution that so far (3 days and one 60min ride) is working perfectly: at the non-faulty end of the spring, I took a small nail and bent it to a curve matching the curve of the spring and placed it under the spring. My thinking was that that will push the spring so that there will be more tension on the other and it will make it harder for the other end of the spring to jump out of the hole that it is supposed to grab. It worked perfectly so far.

It might not last forever, but it was a $0 fix. If I were planning a long trip with the bike, I would probably still replace the derailleur, or try to buy a new spring (nothing was visible wrong with the spring or the body, though), but so far, I am very satisfied with my fix.

Hope this helps someone out there.
 

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Thank you

Incredible job! :thumbsup:

Ha! Wonderful work taking a chance and like you had mentioned you had nothing to lose. I'm curious what had changed with the spring inside of there but I'm relieved you were able to repair it with just some elbow grease. Thank you for updating us for posterity and for anyone with the same question in the future. Thank you for coming back on this thread and taking the time to let us know the solution. :)

Best regards,
Jason
 

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Discussion Starter · #6 ·
Thank you Jason!

>I'm curious what had changed with the spring inside of there

My working theory is that the spring creates two forces:
1. the "real" function of the spring, a tangential force, that rotates the arm of the derailleur relative to the derailleur body.
2. a "pushig out" force, like the force in a rear shock coil.

The two ends of the springs are bent and each of them grab a hole. One end grabs a hole in the derailleur body (this was the problematic end in my case), the other grabs a hole in the arm of the derailleur, the part that closes down the derailleur body like a lid. This is how the spring can rotate the arm relative to the body and create chain tension.

Force 2. helps this "grabbing" of the spring into the holes as it pushes the end of the spring into the holes. I wanted to make this push out force stronger by adding the nail and therefore reducing the space for the spring (similar to when making the spring tighter in a rear shock by making the space for the coil smaller). This could have a devastating effect on the "good end" of the spring as there it can make the "grabbing" weaker, but luckily I could put the nail at almost a full rotation away from that part where the "good end" grabs its hole and in a place that just happened to be right under the "problematic end".

I drew a picture of it, hope it makes sense.





 

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Discussion Starter · #7 ·
Just an update: I have been using the bike ~ twice a week in the past 5 months and the derailleur has been working flawlessly with the "nail hack".
 
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