Hello. My first post is a question.
I have a 7-sprocket Shimano freewheel with a broken tooth. Not wanting to damage the chain, I’ve been staying off the seventh ring.
I got a replacement from Amazon, Shimano, same number of sprockets, teeth per ring, basically identical. The only difference is the old one was all press fit together and the new one is mostly pressed with the two upper rings being riveted to ones below.
When I installed it, I experienced a grinding sensation through the chain in all gears. No real noise, just the feeling. BTW, sprocket spacing is same as OEM.
It was installed correctly (no crossthread) and I do most of my riding on the center gear ring up front so not a chain alignment thing.
Put the old freewheel back on and back to normal.

Anyone ever experience this?

(btw- the new part is Shimano MF-TZ500-7 if it matters)

Thanks

Maybe the old sprocket was worn to the old chain? Did you put on a new chain, or using the old one? I don't wrench and work on bikes much these days, so other than that, I got nothin'.

When replacing rear sprockets of any type, you should always replace your chain at the same time. This is most likely the cause of your ‘grinding’ noise or sensation. You should never pair a worn chain with a new sprocket or vice versa.

Measure your chain. It should measure exactly 12 inches from outer plate to corresponding spot on the 12th link away. If it is more than 12 1/8", then it's toast and probably the reason you broke a tooth. If the chain is NOT worn, it could still have sand in it to make the grinding sounds. Or if by "grinding" you mean "clattering," then you just need to adjust the cable tension so that the jockey pulleys line up with the gears on the new cassette.

You mention the outer two gears not being riveted. This implies to me that you have a cassette on a freehub, not a freewheel.

I had that very thing happen when I changed an old freewheel with a matching new one. I wound getting not only a new chain, but also chainrings. The old ones were really worn down. Everything worked fine after that. New Shimano rings at bikewagon.com were cheap. If I remember correctly, the 53t ring was 19.95 and the 42t was 9.95. I think I saw them on bikewagon recently both at same price, 9.95.

Chain for 6-7-8 speed is also cheap.

Lower end cranksets the rings are often not replaceable.