What thread does the b-screw on a shimano rd-6400/6401 have? What thread does the b-screw on a shimano rd-6401 have?
I need to recut the thread but am not entirely sure if it's an M4 fine pitch or something else.
I have in front of me an RD-6500, Ultegra 9s rear derailleur. The B-screw is an M4 x .75 pitch x 12mm length. Looking at a couple older shimano derailleur's, it appears that the B-screw is also an M4.
Shimano's website has various technical documents, some of which are &quot;exploded view&quot; diagrams of the parts that make up the part. At the bottom is the list of the parts, and when it's a fastener, they often give the size and length of it. However, the exploded view of the RD-6400 does not have the size of the B adjust bolt. Here is the EV of the RD-6500 which does list the B-screw as an M4 x 10mm.