Front sprocket, just came of...

[tek_tuk]

Hey there all!
A short while back I got me a, visually, quite descent 89-sport.
Now, when autumn, dampness and darkness descends over the grim north and the garage is warmer and friendlier than the open road I have started picking it apart.
Imagine my novice surprise when I started a drive line change and, after the sprocket cover came of, there was absolutely nothing to keep the sprocket on to the drive shaft.
I am quite new to bikes overall, all my knowledge is from cars, but after digging around on forums I have realized that there are a couple of versions on the sprocket carrier and the plate but...
The front sprocket that came of has a plate welded to it the plate has a hole. The driveshaft has one centric and threaded hole but it seems somewhat damaged.
The new sprocket has two smaller holes adjacent to its splined center. I have no retainer plate what so ever.
I checked the original sport workshop manual and I couldn't quite make out how the retainer plate keeps the sprocket in place but it shows the retainer plat and the two adjacent holes and screws.
Do I need to get an entirely new drive shaft here or whats my best way out.

Can anyone help an enthusiastic Ducati novice out here, I will try to get some pictures up as soon as possible but any primary thoughts will be very appreciated.

Thanks alot,
Horst
Stockholm
Sweden

[Tamburinifan]

I checked the original sport workshop manual and I couldn't quite make out how the retainer plate keeps the sprocket in place but it shows the retainer plat and the two adjacent holes and screws.

Retainer plate mount holes fixates the plate a little offset towards the splines.
So therefore it locks to the sprocket & gear shaft.

Yup, winter f sure has arrived in Sweden.

[ir_joep]

Hi,

I have an other system where the sprocket is rather "thick" and fixed with a centrale bolt.

There are some lines written about this some time ago, or did I read it at the paso forum? I do not rember.


Cheers Joep

[Maico88]

I have a 1990 Sport that apparently has the same type of sprocket that yours does. Here is a picture of the setup. I hopr that this helps.

[ducinthebay]

If you have the central bolt version, then it is important that you let the sprocket move a bit when the bolt is tight. The bolt should have a shoulder or sleeve that tightens against the shaft before it tightens against the sprocket. If the bolt tightens against the sprocket, the movement of the sprocket will loosen the bolt. No amount of Loctite will hold that bolt in.

Cheers,

[Finnpaso]

Its easy also to make holes to those allen screws and put then safety wires through them... I have used such "mod" in my Ducatis.

[tek_tuk]

Thank you all for your valued insights I really appreciate it!

I was down fiddling around with the bike and a new front sprocket the other day...
Well, I cant really get any wiser with this.
-The drive shaft has a crest/crease? so that the two bolted retainer plate should fit.
-The splines of the drive shaft widen and get thicker close to the gearbox.
-The drive shaft allso have a internal hole with M-screw groves so that it could actually take a bolt to hold the sprocket.
-The new sprocket has the two holes for the retainer plate.
-When I fit the new sprocket it seems to line up with the rear sprocket but it wont go all the way on the shaft because of the widening splines so that fitting the retainer plate is impossible by 4-5mm, actually it stops flush with the drive shaft.

Does anyone have any pointers to which sprocket to buy and where to find it?

Thanks again for your help!

[carlopalmas]

I had this happen years ago while I was on a road trip in Montreal. I think a great deal has to do with the sprocket. In retrospect I noticed that my sprocket had some wobble when mounted on the spindle. The wobble turned into a rocking motion that slowly ate away at the teeth on the retainer. No amount of safety wire in the world is going to prevent the retainer to come off in this case.

Double check the sprocket, make sure there isn't too much wobble, use the mounting screws and you can probably use a central screw in the spindle with a washer as a safety measure. Carry a spare retainer and check regularly (or at least before a long trip).

In my case I got really lucky, the Ducati dealership in Montreal called a fellow Italian whose bike had the same retainer mechanism and he stripped the parts of his bike so I could make it home. Really cool of him

from the land fo spaghetti!
Carlo

[ducinthebay]

Retainer plates are a replaceable item. Replace them often, at least with your sprocket. Ducati had a run of soft ones which wore out very quickly. (around 98)
The sprocket is made of softer material than the output shaft. So, if there is too much free play, then it should be replaced. I haven't heard of anyone shearing off all the teeth yet, but that is a problem with older VW rear hubs.
You should always put a thick grease in between the shaft and the sprocket. it reduces wear on your shaft, and also acts as some amount of damping between the parts, which also reduces wear.

Cheers,

[Finnpaso]

I would add, that such grease what have molybdenium...