right, i have a loose cassette, (sram powerglide ) i have tryed tightening it up with a cassete tool but it will not go any tighter, but it still wobbles. i though that something could be wrong with the hub? correct me if im wrong ?

matt.

well it shouldn't be a loose body because if you were doing it up it would hit the end stops on the cassette body.
when you do it up doesthe lockring keep spinning or will it actually tighten?
if not the lockring threads in your cassette body have gone.
if the actual cassette body itself is wobbling then you'll need to locate the bolt that holds it together and tighten that up.
which hub are you running?

What hub is it?
What speed is the cassette?
If you are running a 9spd compatable hub and an 8spd cassette, chances are you will need a cassette spacer.
J

Am i missing something here?  I thought 8 and 9 speed cassettes were the same width, thats why 9 speed uses a narrower chain.  IF you use a 7 speed on a 8/9speed freehub then you need a spacer?

Re the loose cassette have you removed it and lost a spacer or something?  You must be able to tell whether the freehub is loose as well by looking between the spokes and big ring when wobbling it...

MY old shimano freehub could be tightened by removing the axle and using a 10mm allen key on it, that was about 7 years ago though so may have changed now

8spd and 9spd are the same width.

I suspect your freehub is loose or buggered.

Take it to a bike shop.

Grab hold of the cassette and wobble it - if it moves as one the freehub is loose - if the sprockets move indpendently of each other it's the cassette.

does the free wheel move.  If it does you will need to tighten it.