Replacing Rear Mech Spring. How?

[Thame Game]

I have to replace the B tension spring in my XTR M950. Thanks to member Matttymm, who sent me one.

I've had this problem before with other rear mechs. How do you wind the B tension plate back in with the spring without it distorting or scoring an ugly gouge across the mech?

 

[ishaw]

It's a bit of a pita to do and explain.

What has worked for me is to do it without the hanger bolt in situ. Seat the spring in the mech body, push and twist the tension screw part into position. Slot the bolt through and slide in the c-clip.

Sounds easier than it is, I have found on occasion it may need a set of pliers to hold it all together while you slot the bolt and c-clip in.

Or do it with the hanger bolt fitted, but I find you get less movement to wind the tension spring into place over the stub on the body. It can work easily or be a pain this way, worth a go as easier to hold it all in place with pliers while you fit the c-clip.

 

[Thame Game]

Just had another afternoon of it and the spring is going the same way as the one I knackered last week.
Just when I think it's in and the c clip is on, the mech feels horrible. It's as if the seating pin nearest the outside face has dislodged and is dragging around with no return springiness (if that makes sense).
I've scratched it all up now with frustration.
Think I'll just replace the whole unit.
Lesson: DONT dismantle these mechs!

 

[ishaw]

Another tip I've just remembered from memory is that you can use the b-tension screw bit as a means to rotate it all into position.

Iirc one end of the spring is longer than the other, I can't recall which end the longer end goes into but maybe whatever way to have it now, try it up the other.