M900 Rear Rim / Rear Sprocket Flange Gap

Dellikose · July 16, 2011, 04:54:14 PM

Gentleman,

While adjusting my chain tension on my 1999 M900, I noticed that there is a gap between the rear wheel and the sprocket flange. I started to take a closer look and then found that it looks like the studs that bolt the rear sprocket on, or maybe the nuts, have made contact with the swingarm and tensioner plate.

It's not too bad, but there are definitely gouge marks from where they have hit. The previous owner said that he had the tire off at some time in the past...is it possible that he forgot a spacer?

I've been having problems with keeping proper chain tension...could this be the reason why?

Howie · July 16, 2011, 08:01:20 PM

A gap between the wheel and sprocket carrier is normal, the gauges are not. Photos would be helpful, plus you may need to disassemble to inspect. Meanwhile, don't use the bike. There is a cone shaped spacer on the sprocket side. The flat side goes towards the swing arm and the cone faces the bearing. A parts diagram is available at http://www.ducati.com/services/maintenance/index.do They don't go back to your year, but 2001 will work.

Also check for worn/lost cush drives. This will cause the sprocket to wobble.

Dellikose · July 17, 2011, 06:03:58 PM

Sorry it took so long to get the pictures, had the last day of the MSF today...

First, yes I know my bike and chain are dirty... that's why I was down there in the first place!

You can see how close the nuts come to the tensioner plate and swingarm. I didn't see the cone spacer you were talking about. I'm in the process of ordering a rear stand now so I can take the wheel off.

Another thing I noticed was that when the axle nuts are loose and I rock the bike, the wheel doesn't move in the swingarm slots, like it is hung up.

ducpainter · July 18, 2011, 04:14:52 AM

The gap is normal, but as howie said, the spacer is missing or in backwards.

Your chain is probably at the end of it's useful life which will cause frequent adjustments being necessary.

It could use some lube.

Dellikose · July 18, 2011, 04:49:40 AM

Yeah, the more I sit here and think about it, it is probably the spacer. When I swung the tensioner plate down and looked in the swing arm I saw metal shavings.

The rear stand will be here in a few days and I'll be able to disassemble everything and inspect it. If I need to replace the spacer due to wear, is it hard to get ahold of?

While the rear wheel is off I plan on checking the bearings and cush drive. Is there anything else that I should be looking out for?

I should also add that she has about 24,000 miles on her.

the_Journeyman · July 18, 2011, 06:07:44 AM

Best I can call, that reddish stuff is what the o-rings are supposed to hold in, so dp is correct. Time for a new chain.

The gap is normal, both my M750 and my SS900 had that gap.

JM

Dellikose · July 18, 2011, 11:28:24 AM

Quote from: the_Journeyman on July 18, 2011, 06:07:44 AM
Best I can call, that reddish stuff is what the o-rings are supposed to hold in, so dp is correct. Time for a new chain.

Ah, I just figured that it was residual chain lube from the previous owner. Is this color typical with bike chains? It is a Regina chain if that helps.

And for my reference, could someone please post a picture of the cone spacer either on or off the bike?

Speeddog · July 18, 2011, 12:04:07 PM

Quote from: Dellikose on July 18, 2011, 11:28:24 AM
Ah, I just figured that it was residual chain lube from the previous owner. Is this color typical with bike chains? It is a Regina chain if that helps.

Long Explanation
That red stuff is Hematite, alpha-Fe₂O₃, one of many versions of 'rust'.
It is debris produced by fretting corrosion.
Fretting corrosion is caused by small motion under high load with inadequate lubrication.
Moto drive chains fall into that category when the o-rings fail and let the grease out.
It is a terminal condition.

http://www.rexnordcomposites.com/tuflite/reference/fretting-corrosion.asp

Short Explanation

Your chain is shagged.
Replace it, and both sprockets, while you have the wheel out.

Howie · July 18, 2011, 12:41:03 PM

If that is indeed fine red rust verses orange surface rust you neede a chain and sprockets yesterday.

Dellikose · July 18, 2011, 01:58:53 PM

Yes, it is indeed the fine, red rust...so now I can add sprockets and a chain to the list.

I already have a replacement "tube" spacer and two wheel bearings that I'll end up throwing in. While the wheel is out, degrease and clean the swingarm and adjusters.

Luckily we have storms lined up for a few days, so it's not cutting into seat time too much

ducpainter · July 18, 2011, 02:06:31 PM

Quote from: Dellikose on July 18, 2011, 01:58:53 PM
Yes, it is indeed the fine, red rust...so now I can add sprockets and a chain to the list.

I already have a replacement "tube" spacer and two wheel bearings that I'll end up throwing in. While the wheel is out, degrease and clean the swingarm and adjusters.

Luckily we have storms lined up for a few days, so it's not cutting into seat time too much

The spacer we're referring to is a cone spacer.

If you go to http://www.ducati.com/services/maintenance/index.do

you can download a parts manual for the '01 M900. The wheel parts are the same and you can see what the spacer looks like.

COP TZR · July 18, 2011, 08:52:56 PM

if you need a replacement cush drive/carrier, I've got one complete with the spacer that you will need. I hope it all works out for you.

Dellikose · July 22, 2011, 04:17:30 PM

A disclaimer: You may want to put your children to bed as the next few images are very graphic

Now that we got that out of the way...you guys were right, the cone spacer was put in the wrong way. Well, it looks like it has been that way for a while and the swing arm really took a beating.

I'm guessing that the swing arm is shot, as these grooves are nearly all the way through the aluminum.

Here's the cone spacer, it looks to be in pretty good shape. Would it be reusable?

I'll count this as a lesson learned, and hopefully some other newbie will check his spacer to make sure the same thing doesn't happen!

Off to eBay! What model year swing arms are interchangeable with mine?

Thanks

Howie · July 22, 2011, 07:32:29 PM

The swing arm could be filled with weld and smoothed. I would replace the spacer, I doubt it is expensive.

COP TZR · July 25, 2011, 10:05:32 PM

Quote from: Dellikose on July 22, 2011, 04:17:30 PM
A disclaimer: You may want to put your children to bed as the next few images are very graphic

Now that we got that out of the way...you guys were right, the cone spacer was put in the wrong way. Well, it looks like it has been that way for a while and the swing arm really took a beating.

I'm guessing that the swing arm is shot, as these grooves are nearly all the way through the aluminum.

Here's the cone spacer, it looks to be in pretty good shape. Would it be reusable?

I'll count this as a lesson learned, and hopefully some other newbie will check his spacer to make sure the same thing doesn't happen!

Off to eBay! What model year swing arms are interchangeable with mine?

Thanks

check your PM's. I sent you a msg.

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M900 Rear Rim / Rear Sprocket Flange Gap