Loose cassette

[FZRIP]

I’m a little confused… easily done.
I’m swapping a 7 speed 12-27 for an 8 speed 11-30. The 8s cassette fits fine on the freehub and the locking screws up fine, but the cassette remains loose.
If I use the last 12t sprocket from the 7s cassette it seems to tighten up fine.
Can anyone shed any light on this?
Pics of cassettes below if it helps.
Thanks

 

[novocaine]

hard to tell from picture of 8 speed, but looks like there is a spacer between 3 and 2 missing.

 

[FZRIP]

All spacers in place.

 

[novocaine]

really, I thought it was between 2 and 3, but actually 1 and 2 looks narrower in that picture.
Shimano had a thin shim on some cassettes in the 8 and 9 block, I've had it a few times now where someone hands me a cassette and complains about it. measure the gap between cogs.

 

[benjabbi]

Is the freehub threaded for a Uniglide cassette? If so the 11 tooth won't go all the way on, those freehubs were meant for 12 tooth smallest sprocket. You can put a spacer behind the cassette. As long as that doesn't push the cassette out into the dropout.

 

[FZRIP]

That sound like it. Thank you.
Is there a known spacer width?
Any mods to allow fit without a spacer?

 

[benjabbi]

2mm should be enough.
If the cassette is old enough to be bolted together you'll have to to take them out. Or get hold of an old Mavic or Hope spacer that has cutouts for the bolt heads. Or file some cutouts into a spacer.
Not really any mods short of fitting a more modern freehub to the wheel.
I suppose you could theoretically file the threads off the end of the freehub but that sounds like an immense pain in the arse.

 

[FZRIP]

Looking more closely at this, the obstacle seems to be the 11t and 12t sprockets.
The 11t is “blind” and does not pass far enough onto the freehub to clamp the rest of the cassette.
The 12t is “open” and will fit fully along the freehub to clamp the cassette.
the 8s cassette clamps up fine with the 12t, but it’s a different width so I assume the shifting will be iffy.
Am I just confusing myself..

 

[benjabbi]

That cassette should fit on that freehub.
Yes the 11t doesn't go all the way onto hub. That's why the splines stop short of the end of the hub. Also why the threads on the older ones that go to the end, stop the sprocket fitting properly.
There could be a shaped washer missing out of the cassette, like pictured below at the bottom. Goes between the main bolted together part and the next sprocket to clear the ends of the bolts. I did think these were gone by 8 speed. But maybe not?

 

[novocaine]

Looking more closely at this, the obstacle seems to be the 11t and 12t sprockets.
The 11t is “blind” and does not pass far enough onto the freehub to clamp the rest of the cassette.
The 12t is “open” and will fit fully along the freehub to clamp the cassette.
the 8s cassette clamps up fine with the 12t, but it’s a different width so I assume the shifting will be iffy.
Am I just confusing myself..View attachment 930718View attachment 930717View attachment 930720

free hub isn't thread for UG.
it's a spacer missing between 1 and 2.