XTR M900 rear mech setup issue

[RockiMtn]

anyone with knowledge about servicing the m900 rear mech? i have another one in working but tatty condition that i'd be willing to cannibalize to make this one work.

 

[Tallpaul]

Ugh… soaked the pivots with degreaser, ran it under some hot water, dried and then re-lubed. Darn mech still won't shift down into first. 2nd to 8th perfectly fine though. :roll:

Which sprocket are you calling first? :?

 

[FluffyChicken]

There's not much servicing you can do. Anything in the parallelogram is generally out of bounds unless you wish to 'try'.

You have adjusted the spring to it's higher setting ?

 

[RockiMtn]

Ugh… soaked the pivots with degreaser, ran it under some hot water, dried and then re-lubed. Darn mech still won't shift down into first. 2nd to 8th perfectly fine though. :roll:

Which sprocket are you calling first? :?

smallest/lowest, 11T or 12T, whichever it is.

 

[RockiMtn]

There's not much servicing you can do. Anything in the parallelogram is generally out of bounds unless you wish to 'try'.

You have adjusted the spring to it's higher setting ?

Yes I have. Guess I'll just have to run it as a 7 speed rear till I source another nice XTR M900 rear mech.

 

[Panza]

There is absolutely no point in de-greasing the dérailleur IMO.
The reason for this is that the pivots are actually sealed with small rubber gaskets. IF the degreaser gets in, it will never get out again properly.
What you should do is to just clean it with normal soap and water, then soak it in WD40 or CRC 5-56. Both of those lubricants have creeping qualities that will let them get past the seals and into the pivots.
But your dérailleur may have a fabrication defect that no oiling will improve.

 

[RockiMtn]

so decided to bring this thread back. i've swapped out with a replacement so now i have beautiful specimen sitting doing nothing, which i find a shame. as stated, not sure if it's just a defective weak spring or sticking pivots.

i may have a go in soaking the whole unit into some lubricant or something. so there's no way of replacing the spring, is there?

 

[utahdog2003]

so decided to bring this thread back. i've swapped out with a replacement so now i have beautiful specimen sitting doing nothing, which i find a shame. as stated, not sure if it's just a defective weak spring or sticking pivots.

I may have a go in soaking the whole unit into some lubricant or something. so there's no way of replacing the spring, is there?

Let me prefface this by saying that I don't remember too well these days, so if I have the model numbers wrong, somebody slap me!

Around about the time the bassworm was offered up by Sram as a fix for the Shimano weak spring syndrome (which you are clearly suffering from...(all that cassette stuff is overthinking the issue...sorry pal! ) there were a couple companies who offered a stiffer return spring replacement. The springs were very common retrofits for the 910 and the 739 rear derailleurs of the day. Basically, they turned the new light action derailleurs into one which felt more like the older 900 and 735 stuff.
They are very hard to find, and I wouldn't waste my time if I were you. You could do three things...1)-Use a Bassworm...tey are stupid looking things for sure, but they work. 2)-STI Rapid Fire! Shimano shifters solve all weak spring syndrome issues...99% of the time. or finally...3)-Sell or swap your 910 to a friend locally, with the understanding that you can guarantee for him that the derailleur will work with above mentioned STI, or your money back.

At the shop I worked at in Colorado back in the day, we were good friends with the Sram rep in the region, and so we were heavy into selling Sram stuff, and we worked feverishly to make Grip Shift 500 and the later X-Rays work with Shimano derailleurs. Bassworms, Johnny Snot, replacement springs, we tried it all. I must have swapped out a hundred return springs in those damn derailleurs, and my fingers hurt just thinking about it.

This is all a lesson in Shimano marketing aggression. When 900 and 737 swapped out for 910 and 739, the reason Shimano gave was lighter action and better feel, but the real reason we all discovered, was that the new derailleurs and their limpy springs, worked like ass with Sram twisties. Shimano couldn't stop people from buying competitors shifters by choice, so they figured out how to do it out of need.

If it were me, I'd put it on a shelf or trade it out with a friend for a 900.

Or run Thumbshifters.

If your replacement derailleur is a 910 also, then you are a lucky man. Don't get it dirty! Either that or I'm making all this up in a drunken stupor. I am enjoying a nice Pinot Noir this evening... :shock:

 

[RockiMtn]

Thanks for your lengthy contribution, but… the rear mech in question IS a M900. :?

 

[utahdog2003]

Thanks for your lengthy contribution, but… the rear mech in question IS a M900. :?

Ugh. Then it is tweaked. :cry: That is a shame for such a lovely derailleur.

Bookshelf?

Decorate your toilet tank with it?

Avant garde keychain?