Originally Posted by
rccardr
Thanks for the video. That trick with the allen key to tension the spring and install the backing plate before inserting the C clip is pretty slick.
Learned something new!
Right, yes the use of a small hex key to rotate the backing plate before pressing it against the spring is the single most important tip in all of this. This step would drive me crazy until I figured this out pre-Youtube. Sometimes you need a small set of vice grips to (carefully!!) compress the backing plate against the spring tension. Since the Dura-Ace and XTR units have alu backing plates, extra caution is required, as this plate is easily bent, unlike the steel plates found in the lesser derailleurs.
On the subject of water: don't use a pressure washer to clean your bike. The derailleurs that I've been handed seized up and misdiagnosed as "having bad springs" all had this problem. Upon disassembly, not a trace of grease/lube left in the 2 cavities, but just corrosion. Water has no place in bike maintenance; if you need a degreaser, then there more effective and less corrosive products, such as mineral spirits.