Sprocket wobble

Brett Kerby · Post by **Brett Kerby** » Sat Feb 14, 2009 6:02 pm

OK I just finished putting new sprockets on the bike, and I noticed that there is a little play in the rear sprocket, actually the whole sprocket mounting hub. By play I mean I can wiggle the whole thing some with my hand. Is some play normal? Also my chain seems to get tighter in a couple places during the rotation of the tire ie almost 1/2 in difference in places. It is a new chain also. Did I muck something up or is something just not right. The bike is a 73 Gt250, And I know jack about bikes. Any help is greatly appreciated.
Thanks Brett

Arne · Post by **Arne** » Sat Feb 14, 2009 6:20 pm

Make sure you have all the spacers in there in the right spot and that the axle nut isn't too loose.

Check bikebandit.com for parts lists for general layout.

Also make sure the axle is square with the frame (little marks on the swingarm and the bolt on each end of the swingarm.)

This guy has some basic good starter info on bikes:

http://www.dansmc.com/MC_repaircourse.htm

kmil · Post by **kmil** » Sat Feb 14, 2009 7:48 pm

I had the same problem on my T350 and found the hub bearing was bad and had worn out the spacer inside the hub. Got replacement used parts off E-bay. Good Luck, hope it isn't to bad.

kmil

Brett Kerby · Post by **Brett Kerby** » Sat Feb 14, 2009 11:58 pm

Well thanks for the replies the motorcycle repair link is great, that will provide me with tons of reading. I am going to tear into it tomorrow hopefully and see what I can find. Will use the diagram off bike bandit as a resource. Will report back what I find. Kinda wondering if it was a bearing but thought that would make the whole wheel wobble? Old girl only has about 5k on it so it shouldnt be too bad

...famous last words.... Thanks again fellas......Brett

tz375 · Post by **tz375** » Sun Feb 15, 2009 9:17 am

Brett, on some bike the sprocket is bolted to teh wheel so there should be no wobble unless teh wheel bearings are shot and then teh whole wheel wobbles.

Where the sprocket is mounted on a separate plate as part of a cush drive, that "plate" has its own bearing outside the wheel hub and if that is shot, the sprocket and mounting plate will wobble.

Brett Kerby · Post by **Brett Kerby** » Sun Feb 15, 2009 5:13 pm

Well no signs of bearing failure that I can find such as scoring, deep scratches or pieces of metal, but I do find that there is some wiggle in the sprocket mounting drum at the bearing/drumspacer(hub retainer) joint. Looks to me like the bearing is worn enough to allow this movement. Also where the sprocket drum rests on the cush drive it does not sit level at all and wobbles a lot. Does this mean I need new cushions or will replacing the bearing negate this movement? Feels like the fins bottom out in the hub possibly? Thanks again for the help thus far, you gents are awesome...Brett

rbond · Post by **rbond** » Mon Feb 16, 2009 4:37 pm

All of the bearings should spin smoothly, maybe not too freely only from drag caused by the seals. Also the inner race should not noticeably wiggle with your finger stuck in it to turn with. The fingers of the sprocket carrier should fit lightly snug in between the cushions and fit somewhat flat. If it does not a spacer is not correct or missing. With the proper spacers, good bearings, etc. there really should be very little if any wobbling of the sprocket. Unlike as it sounds, you may have accidentally swapped spacers.

Brett Kerby · Post by **Brett Kerby** » Mon Feb 16, 2009 5:15 pm

Spacers appear correct with diagram, but what I found is that it is the hub spacer making contact with the wheel bearing that is causing the wobble. When I take spacer out the sprocket hub fits good with very little wobble. Maybe have a bearing that is not driven in far enough or something is only thing I can figure. Gonna play with it some later tonight and see If I can figure it out.

Post by **Suzsmokeyallan** » Mon Feb 16, 2009 6:30 pm

Thats designed just like the Titan where the sprocket hub carrier assy is separate on the swingarm when the hub/wheel comes out.
Try the sprocket carrier unit on the swingarm tightened up without the chain on it or the back wheel and see where the play is coming from. It should spin true free with no play. Look at the flats on the stub axle and how it passes through the swingarm and the adjusters hole on that side, make sure its seating fully into the carrier once its all installed.
The seal should be removed and the bearing checked to make sure its installed down into the lip on the carrier. If necessary check the trueness of the spacers width...

Brett Kerby · Post by **Brett Kerby** » Sun Mar 22, 2009 8:33 pm

Sorry it took so long to get back on the whole sprocket wobble thing. Ended up that the stub axle had to be machined 1/16 in shorter as it was not allowing the sprocket hub to seat fully in the cush drive allowing the sprocket to wobble. Got her all back together and it is solid as a rock. Thanks for all the replies guys your advice is greatly appreciated..Brett