Originally Posted by
Velo Mule
The cassette sprockets are rusty for sure, however, there does not seem to be too much wear. I don't see sharks fins or hooking on the tops of the sprockets. This may be salvageable. Is the hub still good? If so, there are several methods to remove the rust:
Evaporust
Wire Wheel
Sand Paper
Vinegar
What I do is to grind off the rivets on the largest sprocket to break the cassette down to the individual sprockets. The you can clean them up. The rivets are not needed to reassemble. They were only there to make assembly easier in the factory.
No need to go that far. Degrease with a great degreaser, scrub the crud out. Find a container that can hold the cassette as is, and cover with Evaporust. 24 hours later, scrub and rinse, and you should have a squeaky clean cassette. I don't like rust specks, so I've taken to coating the cogs with Fluidfilm to block moisture and oxygen from the steel after a rust removal.
Word of caution if you're replacing: Later Suntour cassettes and hubs had two flavors, Accushift Plus, and Accushift Plus Microdrive. The Microdrive system was meant to reduce drivetrain weight by using 6 speed length freehubs and higher cassette gearing (in 7 speeds) paired with smaller chainrings. Fortunately, the cassettes are easy to spot with
two cogs as part of the lockring instead of one. The hubs are much harder to identify, but paying attention to rubber seal that sits proud of the freehub body is a good check.