XTR rear mech setup issues

[madlan]

Hello everyone, i was wondering if you could give me some advice on a problem i have been having?

I have an XTR M960 rear mech that will not change onto the largest sprocket.
I have tried everything i can think of, i have reduced the chain length to the correct size and spent hours adjusting the H, L and B screws to no avail.

The mech is rapid rise, so i would have thought the top sprocket would be no problem at all, as the mech naturally sits there at rest.
If i pull the mech down slightly it changes, if i push the mech towards the wheel it changes. I have also removed the gear cable so the mech sits as close to the wheel as possible. the L screw has been relaxed to allow the mech to move past the large sprocket, which it will do if i push the mech to make it move up.

Is there something i am missing here? its driving me crazy!

The only thing left to try is replacing the XT cassette with a new XTR maybe that will solve the problem?


Many thanks!

Alan.


Crank & Bottom Bracket: Shimano XTR Cranks HollowTech II & BB M960
Cassette: Shimano XT 9sp
Rear mech: Shimano XTR R-Mech Rapid Rise M960
Front mech: Shimano XTR F-Mech Conventional M961
Chain: Shimano Dura Ace Chain 9sp 7700
Cables: Avid FLAK JACKET Front & Rear Gear Cables

 

[madlan]

update:

If i stick a piece of metal under the B screw, to increase it by about 5mm it works fine! very odd.

Is it possible to replace the B screw with a longer one? would this cause any problems to the mech?

Alan.

 

[matt_tyrrell]

I spent ages trying to set-up an XTR RR rear mech and had all the same problems. Even when I could get it working It went out of true at the first sight of mud.

I think the problem may lie in you cassette. The RR cassettes I THINK are slightly diffrent to the non-RR cassettes. Have you used your XT cassette with RR before? You may have to buy an XTR cassette to get this to work.

Also, if you XTR rear mech is short cage and you have a 34t cassette this may also be a problem.

In the end I gave-up with Shimano last year and moved to SRAM... and have never looked back...

Good Luck