WHAT THE HELL HAS HAPPENED TO MY REAR DERAILLEUR!?

[slomo]

Gentle ride and the gears start making that ticking sound which means cable tension needs to be adjusted.
On completing the ride, i notice that my chain is super slack :shock:
I 'muck about' with the gears for a while and manage to achieve all gears - but i have to remove 2 links from the chain :?
24 hours later, i tell myself i'm missing something.
Remove the derailleur and discover that it won't move.....at all.
It is incredibly stiff and obviously doesn't spring back to where it should (i think the tension from the chain was doing all the work when i removed the links).
I'm assuming a spring of some sort has snapped
Has anyone come across this please?
It would be great if it could be fixed, but it looks terminal to me :cry:
Many thanks!

 

[d8mok]

Re:

Spring for cage has either slipped out of its hole or snapped

It’s possible to fix but can be fiddly

I’ve a XT M750 mech spare if you want to buy another

 

[FluffyChicken]

at the side there is a thin screw holding it together, unscrew that and you get at the cage spring.
It could also be the notch that hold that stops the mech unwinding has been damaged, can't see it though in that picture

See diagram for a look a the pin (#11)
https://si.shimano.com/api/publish/stor ... 0-1796.pdf

 

[slomo]

Many thanks for the help.
I'll have a go at getting it apart :?
Otherwise, i'll definitely be in the market for a replacement.
How much do you want for yours d8mok - hope it's not too rude to ask publicly :|

 

[d8mok]

Re:

£15 plus postage at £3.20

 

[slomo]

Ok, let me see if i can get this one apart, otherwise i'll take it.
The notch/stop (yellow) seems ok to me?
The pin (red) is what i need to remove in order to inspect the spring?
Hmmm.....the question is.....how?
I fear i have already started butchering it

 

[FluffyChicken]

Re:

It's usually an 2mm Allen key, but I've not tried that mech.

 

[2manyoranges]

slomo - I had that once. Broken spring. Fatigued.

I fixed it.

But I tell you what.....d8mok speaks the truth (but massively understates it) when he says 'it's a bit fiddly..'. This is like saying the WC track at Fort William is 'a bit bumpy'. When I did it the job was a few hours (hours!!!) of frustration, curiosity at how the hell they put them together in the factory (special jig? chain mail gloves? arms like PopEye's? or all three), torn fingers and 'why am I doing this?' combined with grit and determination. I did it, but boy was it hard.

 

[d8mok]

Re:

Haha I do agree. It took me maybe 30 mins last time I did one but I’ve done a few now. It’s very frustrating for sure.

 

[ishaw]

Re:

Looks like the cage has a gap/play in it that has allowed the cage to get past the stop. Or did you unwind it for pics?

It is a bit of a faff, but doable, especially if the spring has just popped out of the hole. Sometimes there is a thin washer inside that also has a hole in,that needs to line up with the one underneath. Had this once and couldn't work out why the spring wouldn't fit back in after upgrading a cage.

Can take 5 mins if you are lucky, you do need to contort yourself and the cage to get it back on.

Good luck