Sprocket Bearing?

Associate
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4 Jan 2012
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Sevenoaks, Kent
Hey guys. Recently just got my bike serviced and MOT'd and all was dandy!.. Until 100 miles later.

Was on my way home the other day and got some horrible crunch, clanky like noises and almost felt like I had a flat tyre when going round corners. Sounded like it was coming from my sprockets/chain.

I was told that my chain had a tight spot (but would nothing serious), so got off and checked it to see if they had adjusted it funny, seemed a little on the slack side but nothing too serious.

Anyway, got home done some adjustments to my chain but alas, still the horrible noises. So I decided to pull the rear wheel off. I've never had a bearing go so don't really know what i'm looking at but the bearing on the sprocket seems to have some play, if i stick my finger in the center i'm able to jiggle that part around, easily.

Is this likely the culprit?

Cheers in advance for any suggestions!
 
Soldato
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Sounds like it is the sprocket carrier bearing, yes. Dont ride the bike until you replace it as it will chew up the spacers around it and you'll have to replace more bits.....and it's safer for you to replace it before riding again.

Also if you do it yourself make sure the spacers are put back correctly as they can rub on and destroy the bearing
 
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OP
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Well at least it sounds like my diagnostic skills are on point.

I did have to ride it home, which was around 18-20~ miles from when I first heard it so hopefully haven't caused any excess damage. :(

I'll order a new bearing now. Worth replacing all rear bearings at the same time, or just the individual?
 
Soldato
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Check the rear wheel bearings but just replace the sprocket carrier one if that's all that's gone. It's a fairly easy job as you have access to both sides of the bearing.
 
Soldato
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Take a look at the front one also. Very unlikely it's gone but if it has you got a problem, but it's also possible the front sprocket is loose - just check it.

The rear sprocket sits on rubber spacers (sometimes referred to as a cush drive) which takes the mechanical metal bite of out the force of your chain again the sprocket when it's driven. They do wear out but you should only get movement by twisting the rear sprocket around if you are side on to the bike (sorry kinda hard to explain in writing) a little bit of this movement isn't the end of the world, but any other movement is not good.

I would also check both sprockets to make sure they are still flat/round to ensure they didn't get damaged either.

Probably worth reading up of chain tensions and how to correct adjust it, it's very important, could literally kill you if you get it wrong enough.
 
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I actually ended up ordering myself some rubber cush drive, spacer things (what ever they're bloody called!) along with replacement bearings. They were only £14 so thought I may as well swap them out while I've got the wheel off.

I'm all read up on chain adjustments / tensions so not to worry there ;)

All the bits have turned up at home today so will tackle this tomorrow, I'll make sure to follow up with an update :)
 
Soldato
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Cush drive rubbers rarely need replacing unless they're proper gone which takes a lot of miles.

The easiest way to knock out the old bearing in the sprocket carrier is with a socket which is the correct size to sit on the inner race, then a bit of wood and hammer or a rubber mallet and gently knock it out. I replaced mine in about 25 minutes on my old CB400.

Wheel bearings on the other hand a lot more tricky! :D
 
Soldato
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It's the getting to it that I see the issue with, if it drifts out nice then it's fine but if it's proper stuck then it's a lot harder as you don't have direct access to the other side.
 
Associate
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All done and once again running smooth! Was pretty easy too. Old bearing was... Pooped to say the least.

Honestly, the thing that shocked me the most was the level of noise coming from such a small thing.

Cheers for the help though, guys!
 
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