This derailleur came with Michelle, my 1991 Bridgestone MB-3. Apart from the replacement / upgrading of its jockey wheels to Control Tech sealed cartridge bearing pulleys, the unit has never been serviced.
A picture of the derailleur in its stock form here.
After an external scrub down.
Somehow, the B-tension screw bent over the years. I replaced it with a generic stainless steel 4 mm x 12 mm allen-head screw.
The steps for disassembling the derailleur are similar to those posted for the Shimano XTR RD-M950 GS overhaul. Exceptions are noted in this post.
The cage arm is secured by a single Philips head screw. Removing it allows the sub-assembly to slide out.
Contrary to the RD-M950, the longer prong of the RD-M650 cage arm spring fits into the cage arm. The factory position (tension setting) is the hole closest to the end of the arm.
The o-rings compressed over the last 17 years, allowing ingression of dirt and water.
Derailleur body.
Fully disassembled and cleaned.
41 parts.
All the o-rings were replaced.
For a little more reliability, I replaced the stock Philips head limit screws with stainless steel variants (4 mm x 16 mm set screw w/ 2 mm allen head). HBC's titanium versions will work too, but are overkill for this application.
Shimano RD-M650 rear derailleur overhauled, re-lubed, and reassembled. Don't forget that the B-tension, lower limit, and upper limit screws are now all out of adjustment.
Specifications
Total capacity: 38T
Minimum gear: 12T
Maximum gear: 32T (although I gotten away with 34T with some fiddling)
Weight: 320 grams
At some point in future, the derailleur cable clamp nut (which is beginning to corrode) might be replaced with a corrosion-resistant HBC titanium version.
2 comments:
that's some serious shit man. any ancient organisms living inside? LOL
Very nice. Thanks for showing this. Makes me think, "hey maybe I can do this."
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