Front Sprocket Loose? Cause?

[Tripod]

I have a 2001 S4. Just got back from a 1,100 mile trip.

Started to get a clanging sound when taking off in 1st gear (seemed fine in all other gears).

Just got done cleaning the chain, and found the front sprocket wiggles if I grab the front and rear of the sprocket and pull one one side, pushing on the other..

I presume for some reason the sprocket is failing in some way. Note, this is the sprocket with a cover plate and 2 allen bolts holding it on (not the single central nut).

Aside from replacing the sprocket, I presume the shaft is hardened steel, and should be OK.

BTW, the shaft itself has not play, and seems solid, so not a bearing issue.

Any ideas for the cause of the failure? My riding partner has the identical bike, and there is no play in his front sprocket.

[ducatimike]

Hi Mark,
The cover plate is actually a retainer clip that holds the sprocket from moving off the end of the shaft. If the sprocket is moving past the groove in the shaft, either the bolts are loose or the teeth on the retainer clip have worn out. When the latter happens, the sprocket can shift so far out that the chain can interfere with the clutch slave.

I always change out that clip when I replace the chain and sprockets. I had that retainer clip fail on my ST4 once and eventually lost my chain.

Mike

[Tripod]

Thanks Mike. Ordered a new retaining plate as well as a new sprocket. S/B here today, so I can throw it on tonight.