XTR M900 rear mech setup issue

[RockiMtn]

can't seem to get a rear mech setup properly. without cable/chain my XTR M900 seems to tuck properly under the lowest gear. but when i hook it up, it shifts up okay but doesn't seem to sit back down into first. it seems to hang on 2nd and occasionally maybe slip back into first. if not i use my hand and gently tap it back into first.

is the spring shot? i noticed there's a adjustment screw near the spring inside the cage body. can i use that to make adjustments? also there's a screw near the pivot bolt, what kind of adjustments will that do?

would excess cable loop affect the rear mech in this way? i may have too much and could trim down the cable housing to reduce the loop size.

 

[Andy B]

Have you adjusted the limit screws and the B screw correctly?

 

[REKIBorter]

This is a good place for advice and how-to's

http://www.parktool.com/repair/readhowto.asp?id=64

 

[MikeD]

If it springs back to the small sprocket without a cable, it's a cable problem. Check for tight curves, broken ferrules, gritty cables, anything that'll cause drag.

 

[als0]

If it springs back to the small sprocket without a cable, it's a cable problem. Check for tight curves, broken ferrules, gritty cables, anything that'll cause drag.

also check for kinks in the inner cable

 

[RockiMtn]

shifts from 1 up through 8 fine, and back down to 2nd. just getting it back down from 2nd to 1st is sticky. :?

very little tension in the rear mech to pull it back down from 2nd to 1st.

 

[RockiMtn]

:roll: okay researched my problem and it seems to have nothing to do with the rear mech. Seems the M910 hub I'm using using a later XTR Q-type cassette that's lower profile than the original P-type cassette for the M900 hub!

Can anyone confirm this for me?

And does anyone have a excellent condition Q-type that they'd be willing to swap with me?

 

[Anthony]

I admit that you're going over my head with your cassettes (XTR name dropping I call it!), but I don't see why that would cause the problem you're suffering. If it will run quietly in the smallest sprocket, then basically it should return there.

I've had that problem with a worn/hooked first or second sprocket, a worn chain, or a duff cable/outer, including too tight a curve. Also getting the B-tension perfect helps. I suppose it could be a weak return spring, but gravity is your friend - I think it's usually that something is stopping gravity/nature taking its course.

 

[FluffyChicken]

The cassettes are the same even if they look different (spider wise), but you do need that silver alu ring that should be theres. (actually designed to protect the Alu spider. But you would know if it wasn't as well you wouldn't see it and the cassette would flap around.

You have the B tension screw at the back, but from you description it should be fine. There is a A tension screw (if that's it's correct name) that tensions the jockey cage cage, used to balance out against the B tension. Normal just left alone.

There is the three position setting for the parallel plates, probably the one you are talking about. Large screwdrive slot and black I think ? The tensions the spring your looking for. You'll see the spring move a touch and it.

Though it should work in all three.

Seen as you mention cables... The cable should enter the barrel 'in-line' as best you can, so it's smooth. Not too short so it tugs on the mech and gets a sharp bend, not too long so it pushes the mech or the outer is bending again.

Could be a number of things though, check the cable is running free in the outer casing. Often the inner lining drags on the cable if you didn't tidy the ends up (stick a pencil in the end to widen the inner lining, smooth out any bumps from cutting.

Take a picture of it in position.

 

[RockiMtn]

Reason I started doing research on the wheel/cassette combo is that I gave myself a moment and thought about it. It has never worked properly on any of my bikes. Always a slight issue with it going back down into first. The wheels and cassette was purchased separately. I originally bought the set for my Cirrus, then quickly moved it to my Mongoose Amplifier, and now it's on the Merlin. I always thought the problem was because I never got around to tuning it properly, as I was re-building each bike at the time and not getting much ride time.

I thought a possible solution would be somehow spacing the cassette in more which would solve the problem. But now I think it's the wheel/cassette compatibility do to excepts from Sniperworks. I think I either need a Q-type spider or a later M900-I spider:

http://members.home.nl/children-of-the-korn/XTR900.htm

CS-M900-8:
There are two versions for it:
P-type: The spider holds the 5 largest cogs. (12-32)
Q-type: The spider holds the 4 largest cogs. (12-28 )
The Q-type spider is more compact
and the P-type spiderarms have a smooth surface.

CS-M900-I (1995):
Improved stiffer spider.
Weight: 316 Gr (P-Type).

FH-M910 (1995):
The new model had parallel body for a stiffer hub, called parallax design. They have rubber body caps, to protect the body from water and dirt. The quick release levers have laser cut-out "XTR" in the lever.
Weight: 454 Gr.
The rubber caps on the ends of the hubs:
Also the body is changed for the new cassettes: