I serviced my Mavic Ksyrium SLS wheels a little while back and ever since I’ve been getting a lateral wobble on cassette which is causing a nasty sound when freewheeling at speed (i.e. downhill). I’ve taken the cassette off and put it back on a couple of times which helps for a bit, but it keeps eventually working loose again. I believe I rebuilt the hub correctly and am torquing the cassette back on to 40nm as recommended.

Should there be a spacer on the freehub before the cassette? Should I try it with one on anyway?

Any help appreciated.

Thanks

Is it an 11 speed road cassette? If so you don’t need a spacer. Spacers are for 10 speed road or 10/11 speed MTB.

Sounds like something is not seated properly. Can happen if the freehub gets a little bit chewed up and then the cassette doesn’t go on evenly when you refit it.

If it’s the freehub moving, check the inboard bush. They can wear and cause all sorts of issues, noise and movement. They can be replaced. You’ll have to Google for the parts. Mavic do them and a couple of aftermarket places do over size ones.

Also. Make sure all the bearings are in place properly. I put one of my mavic hubs back together slightly crooked and it dragged the bearing out of position. Everything looked right and ran freely. But the freehub had about 3mm of side to side play.

Have you tried it with a spacer?
Have a Mavic road hub with Shimano 11 speed cassette and that needs a spacer