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Just built up a used 456 frame and am having some problems with indexing...it's running SLX 9spd cranks with 2 spacers on the BB drive side, X7 shifters and rear mech, PG970 cassette, PC971 chain on a Hope XC hub all in good condition. I have a hanger alignment tool and the hanger is dead square.
The problem is it won't drop to the smallest cog on the cassette, with the H limit screw wound right out and cable detached the mech doesn't move far enough across to let the chain jump down, it only makes it as far as the 2nd smallest cog. Does this frame require any spacers etc?
I generally use the guides on the park tool website and all the other bikes I've built/setup index perfectly.
I tried fitting a washer between the mech and the frame...this has kind of fixed it but now when changing to the largest cog the mech is at quite a stretch. I've read about the chain suck issues relating to this frame but don't think this is related....Any ideas?
Does the mech drop down if you pull it by hand?
I've got a feeling that I remember some issues with some mechs. where the return spring wasn't taut enough. As Brant says, can you can move the mech out by hand so that the chain drops to the smallest sprocket? If you can my guess would be a faulty mech/return spring. Do you have a spare mech. you could try?
Thanks for the replies...I just removed the washer and tried it again and it will jump down if I pull the mech right to the end of its travel limit with the H screw all the way out. Maybe it's the mech then? I had a 2009 X9 replaced under warranty due to a sticky action..this is a 2010 X7, I was hoping they would have sorted it. The mech seems to move quite freely but musn't be moving all the way to the end. This is a medium cage mech BTW. I have a spare short cage I could try...
Is the hanger meant to be dead straight on these frames or does it benefit from being slightly angled?
I'd leave the hanger alone if I were you, I reckon that bending it's asking for trouble. If the chain will drop to the smallest sprocket when pulled by hand it does sound as if the mech/spring's screwy, I would have thought that the return spring should pull it out to the full extent that the H limit screw allows (if there's no cable tension to prevent it). Even so I wouldn't have thought that the H limit screw needs to be fully out for this to happen.
I had a similar issue on mine, solved it be increasing the chain tenstion, putting some sealed n fully lubed cables on and putting a small washer on the back of the mech before bolting it to the frame
I have a 456 and an X9 mech and had to wind the end stop way out, which I thought was odd at the time, but it's just about in range.