Originally Posted by dddd

I've found that many Suntour GT-cage derailers work best on even larger freewheels with their B-tension screw removed entirely, when using any modern chain.
And on other brands of vintage derailers, finding a way to adjust the derailer body angle without having a B-tension screw to play with (by tweaking spring tensions, or by modifying the stop lug on the derailer or claw hanger) was time very well spent!

Once the chain gap is tightened up, I further recommend adding some kind of polymer anti-friction noodle to any/all contact points between the cable and any metal guide surfaces, to give much better, more-accurate derailer movement in response to shift lever movement (this after oiling up the shifter's central pivot and friction surfaces).

so-ichiro, what derailer are you using?