After a few requests, I decided to post this as a new thread...
This is a way to increase the tension on the main pivot spring of a Shimano rear derailleur (SRAM derailleurs do not have this spring). This tension increase keeps the derailleur from contacting the frame as is the tendency with Shimano derailleurs on many full-suspension designs, including the Mojo. (This is why we've seen many companies come up with rubber, wrap-around bumpers, including Shimano, who now includes one "stock" on the XTR derailleur.)
In the case of my Mojo build, the rear derailleur is a new 2007 long-cage XTR. This mod takes a little patience as getting the spring out and especially back in, is a bit tricky.
With the derailleur off the bike and in-hand, remove the aluminum "b-tension" bolt with screwdriver and thread in it's place a longer steel one. This will give you some leverage while "detensioning" the spring and keep you from damaging the soft aluminum bolt.
Looking at the backside of the derailleur at the pivot bolt, you will see a c-clip on the pivot bolt that keeps everything together. Remove the c-clip with a small flat-blade screwdriver, keeping in mind the assembly is under tension and is no longer "locked in place".
Holding the derailleur body in one hand, with the other hand rotate that long steel bolt just enough to allow come clearance between the tab and the side of the derailleur body. Wiggle the spring assembly out of the main spring cavity and unwind it releasing the tension.
Now with the spring assembly removed and set aside, look down into the main spring pivot cavity and you'll see a hole where the coil springs inserts. Here's where the mod begins: another hole, about 45 degrees clockwise from the first needs to be drilled. Match a sharp drill bit to the original hole size and carefully drill down in the new location being careful not to go too deep.
Clean out the shavings, add some grease and re-install the spring assembly into the new hole.
Now the tricky part...
Re-wind the spring assembly back in place, again, using that long steel bolt for leverage. When the spring assembly tab lines up with the derailleur body, push it all together and install the c-clip. This took me several attempts as the additional spring tension makes this process tough. Again, patience...
Once you've got this done, remove the steel bolt and install the stock aluminum bolt.
You're done. Now the derailleur is ready to be installed.
This may take the first-timer about 30 minutes. Just take your time on the drilling process and relax for the spring re-install
I have done this mod several times. Frame contact is basically eliminated and I have not experienced any negative affects on shifting.
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Thread: Mojo XTR Rear Derailleur Mod...