XTR M972 rear mech problem

Jamie G

Hope someone can help.

My XTR rear mech developed a fault the other day, as i stretched the cage out to put my rear wheel in, the whole thing 'pinged' and the tension went from the cage. I opened it up and realised the spring had come lose from its mounting inside. So i put it back in, screwed it all back together, but when i put the cage under tension again...ping (tried it several times)

Can anyone shed some light on what the problem might be? Hopefully its not kaput!


Cheers all


Jamie

njee20

Sounds like one of the springs may have gone, both are replaceable, not quite sure which you're talking about. Maybe try your LBS see if they've got an old mech you can cannibalise.

mister p

The tension spring locates into a hole in the body. Unfortunately if it pings out then the hole enlarges and the spring won't stay in. Everytime it pings out it makes the hole a bit bigger and so the spring pops out more easily. It needs whipping apart to see if the body has been damaegd in this way.

allthegearnoidea

on some of the inner bodies ive seen 2 holes for the spring to locate into, ive got a 970 series body in the shed that broke so i'll pop out and have a look,
if youve a spare spring then you could try and make the end point a little longer, there strong springs so isnt the easiest thing to do but may help!

ofcourse, if it is a little enlarged then you could always create a new hole for it with carefull drilling and a fine bit, assuming ofcourse, its not covered under warantee any more??

Chunkers1980

Still don't know what spring he is talking about.

Do you mean the chain tensioning spring in the cage or the spring in the parallelogram?

allthegearnoidea

The one that tensoins the Cage,

Jamie G

Sorry for the delayed reply guys...its the P-tension spring (number 8 on the tech docs PDF below)

http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/RD/EV-RD-M972-2758B_v1_m56577569830721668.pdf

As Mister P says, it sits in one of the holes, and i think what he said about the hole enlargening has happened because i can relocate the spring back into the hole, but when i re-tension the cage it pops back out again

I really hope this can be fixed as i can't afford to go replacing it just now

Thanks for the responses so far guys


Jamie

allthegearnoidea

Have had a look out in the shed at my old mech body, there is a small dimple for want of a better phrase, opposite the main one, so a drilling of a new hole shouldbt be too tricky,



Would give a stronger tension on the chain due to amn extra half turn of the spring, but that can be a good thing sometimes!!

Another thought, quickly looking at the spring on mine it looks like one side had a marginally Longer angled end than the Other, might be worth a check and possible flip round??

*edited for proper image rather than link!

Jamie G

Just a quick update guys. Managed to get hold of another spring that has a longer end point and tried that in there. Seems to be holding up so far, haven't tested it in situ yet so hopefully it holds up alright


Thanks again all


Jamie