Okay, I know there have been a couple of posts lately regarding the spacers inside the hub, but I am starting my own because of what I have just encountered with it and I don't want to muddy up anyone else's post.
Let's get the basics out of the way: I have a 2008 Brutale 910R. I bought it 6 1/2 years ago and it had 7500 miles (12,000 km) on it. I had the 7500 mile service and the 15000 miles service done on it at a dealer. From that point on, I have done all the maintenance on the bike - learning a lot along the way and very grateful to many of the members of this forum who helped me when I needed help. I first tackled my hub in early 2015 with 28,000 miles and found to my surprise that it had a 2010+ upgrade hub. From that point on, I made it a habit to check the hub at about every tire change which is at least once a year. Well, I had a couple of nail in tire situations which meant changing the rear tire more often than normal and I kind of stopped checking the hub (my bad, I know). So... all that's to say that I don't actually know when the last time I checked the hub (and when I say, "checked", I mean removed).
I needed to replace my chain a while back and had trouble getting the rear sprocket. Eventually it came in and I went about replacing the chain. My bike has 47,000 miles (75,000 km) at this point. I took the pin out of the nut on the left/chain side of the axle and the nut was loose - I felt it move when I removed the pin and I was able to unscrew it by hand. I immediately looked down between the sprocket carrier and the hub and I could still see space between the "hat" spacer and the hub, but I could tell it was closer than it should have been. Thankfully, it hadn't gotten close enough to get into contact with the hub/swing arm. I had just been reading some threads on here about other riders and that space running out and making contact, so I was relieved that I at least caught it before that happened.
Okay, so I took everything apart and the hat spacer and "floating" middle sleeve have worn grooves where the chain side sleeve had obviously been spinning independently. Both bearing sleeves looked good. I went to the dealer and it turns out that there are two "parts" of the hub assembly you can order separately and they are the hat spacer and the middle sleeve (you otherwise have to order the whole hub assembly). Obviously parts that seem to have a tendency to get worn. When they came in, the middle sleeve is noticeably heavier. It looks like the original sleeve was aluminum and the new one is steel. I would also like to point out to anyone who has not looked at the sleeves, the two sleeves that ride inside the bearings (on either side of the middle sleeve) have slight tapered edges - so their profile doesn't sit completely flush. - that's why it can wear a grove inside of the other spacers.
I inspected hub pretty thoroughly and it all looked okay outside of those two spacers. Everything is back together and I've put another 700 miles on it since
I can't believe I didn't tighten the nut the last time I had it off (and it had to have been at least a year or more, 8000 miles??), but I feel like that is the only explanation for what happened. I am also mad at myself for not keeping a better record so that I could at least know exactly how long ago and how many miles it has been since I last had it off.
Anyway, just thought I'd share my experience for what it is worth.
The attached images show the space between the hub and the hat spacer (worn on top, new on bottom) and the grooves worn in the two spacers. The middle spacer was worn severely on the left/chain side but also worn a tiny bit on the right/wheel side. I have also attached an image from when I originally took the hub apart years ago that shows two additional spacers with their tapered edges.
Let's get the basics out of the way: I have a 2008 Brutale 910R. I bought it 6 1/2 years ago and it had 7500 miles (12,000 km) on it. I had the 7500 mile service and the 15000 miles service done on it at a dealer. From that point on, I have done all the maintenance on the bike - learning a lot along the way and very grateful to many of the members of this forum who helped me when I needed help. I first tackled my hub in early 2015 with 28,000 miles and found to my surprise that it had a 2010+ upgrade hub. From that point on, I made it a habit to check the hub at about every tire change which is at least once a year. Well, I had a couple of nail in tire situations which meant changing the rear tire more often than normal and I kind of stopped checking the hub (my bad, I know). So... all that's to say that I don't actually know when the last time I checked the hub (and when I say, "checked", I mean removed).
I needed to replace my chain a while back and had trouble getting the rear sprocket. Eventually it came in and I went about replacing the chain. My bike has 47,000 miles (75,000 km) at this point. I took the pin out of the nut on the left/chain side of the axle and the nut was loose - I felt it move when I removed the pin and I was able to unscrew it by hand. I immediately looked down between the sprocket carrier and the hub and I could still see space between the "hat" spacer and the hub, but I could tell it was closer than it should have been. Thankfully, it hadn't gotten close enough to get into contact with the hub/swing arm. I had just been reading some threads on here about other riders and that space running out and making contact, so I was relieved that I at least caught it before that happened.
Okay, so I took everything apart and the hat spacer and "floating" middle sleeve have worn grooves where the chain side sleeve had obviously been spinning independently. Both bearing sleeves looked good. I went to the dealer and it turns out that there are two "parts" of the hub assembly you can order separately and they are the hat spacer and the middle sleeve (you otherwise have to order the whole hub assembly). Obviously parts that seem to have a tendency to get worn. When they came in, the middle sleeve is noticeably heavier. It looks like the original sleeve was aluminum and the new one is steel. I would also like to point out to anyone who has not looked at the sleeves, the two sleeves that ride inside the bearings (on either side of the middle sleeve) have slight tapered edges - so their profile doesn't sit completely flush. - that's why it can wear a grove inside of the other spacers.
I inspected hub pretty thoroughly and it all looked okay outside of those two spacers. Everything is back together and I've put another 700 miles on it since
I can't believe I didn't tighten the nut the last time I had it off (and it had to have been at least a year or more, 8000 miles??), but I feel like that is the only explanation for what happened. I am also mad at myself for not keeping a better record so that I could at least know exactly how long ago and how many miles it has been since I last had it off.
Anyway, just thought I'd share my experience for what it is worth.
The attached images show the space between the hub and the hat spacer (worn on top, new on bottom) and the grooves worn in the two spacers. The middle spacer was worn severely on the left/chain side but also worn a tiny bit on the right/wheel side. I have also attached an image from when I originally took the hub apart years ago that shows two additional spacers with their tapered edges.