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Is it a bearing? Little help please...

Discussion in 'Technical and Troubleshooting Torque' started by 17SJS, Mar 4, 2009.

  1. Hi folks,

    Haven't been riding the GS500 lately, as there's been a whirring sort of noise from the rear wheel (like a car tyre out of alignment - very rythmic and almost soothing :LOL: ), which you can feel through the seat. It's not horrible, but I know it isn't right.

    So, first instinct was chain out of alignment/incorrect tension. Checked the tension, and found I had tightened it based on a loose link, rather than the tight spot in the chain - loosened it off a little and voila, no change in the noise. Damn.

    So, next thought was wheel bearing. Pulled the wheel off tonight, bearing seems to spin pretty smoothly. Then i found this;


    No, my sprocket doesn't have measles! I happened to grab the wheel by the sprocket at those points to move it, and found I could cause a shift in the sprocket alignment (relative to the centre of the wheel) with very little effort.


    The red circled area is where the movement shows - the silver section shifts about 5mm in and out of the centre of the wheel.

    So - my question, what causes this? Is it normal to have that sort of play, or is it a bearing/something else entirely???

    Thanks for any assistance or suggestions...

  2. It's a while since I owned a bike with a sprocket carrier, but memories of the time that I did suggest that, no, movement as you describe with the wheel spindle removed is not a portent of doom.

    The bit that's waggling is the sprocket carrier. If it's anything like my old GSX550, it does not mechanically attach to the wheel but merely slots into the cush drive rubber, which prevents road shocks being transmitted to your gearbox and gives your chain an easier life, that is housed between carrier and wheel hub.

    Movement of the carrier relative to the wheel is only a problem if it's all bolted up and installed and the sprocket still wobbles like Ciderwoman on dole day.

    If it does, fear not. The task of replacement is not huge. I did mine in a couple of hours once, and that included cashing a dodgy cheque at the corner shop so I could pay cash for a new bearing and finding a bearing factor who'd believe I was trade so I could get it for a decent price. If you're not keen to tackle replacement yourself, take the loose carrier to any decent shop or a friendly local Netrider and I'd be very surprised if replacement would take more than half an hour at the outside.

    Of course, it may very well not be the bearing. My suspicions would continue to fall on the chain, depending on how different it is, tight spot to loose spot, or, possibly, wheel balance.
  3. If you lift the sprocket off, you will find what's called a 'cush drive' inside. It's a series of rubber wedges that fit into cleats in the hub. When they are worn they allow the wheel to 'slop around' both in a fore-and-aft direction (jerky gearchanges as they fail to cushion (there's that word) the impact of the chain on acceleration) and also side-to-side movement. Buy new ones and fit them.
  4. Mate, that's the rubber cush drive, pull the sprocket carrier off from the wheel and it will all make sense.
    You will see the rubber bits beneath which are designed to lessen the drive snatch from on/off throttle.

    btw there are 3 bearings in the rear wheel assembly, 2 in the wheel hub and 1 in the sprocket carrier. You can usually check for any movement by placing on the centrestand and seeing if the wheel will move relative to the bike frame. Else while you have the wheel off you can spin all 3 bearing with your finger and check for slop or gritiness (not really a word) when pinning.
  5. Put the wheel back on, don't install the brake caliper or put the chain on. Now spin the wheel by hand and see if it spins freely, runs true, wobbles or makes funny noises. If there's a problem, check the bearings. The movement at the sprocket that you've noticed is normal, I doubt that the cush drive rubbers need replacing.
    As the wheel is off, pull the sprocket assembly out of the wheel and see how the rubbers look.
    Good luck!
  6. That was my next thought - the difference between tight spot/loose spot in terms of slack was probably around 15-20mm as a guess. That seems like a fair bit to me...advice on that point anyone?

    Also something i should have thought of earlier - the front sprocket (last time i had a look at it) seems to me to be very dirty/rusty. Even though the teeth are all fine, should I perhaps lean towards a chain and sprockets replacement? As far as I know they're the original items, and the bike has 20k-odd kms on it...

    Cush rubbers seem ok after inspection too, as does the sprocket carrier bearing. guessing i'm going to be spending a few more hours on this yet... :grin:

    EDIT: The wheel balance shouldn't be out - new tyres only 3 or 4 thou ago...Thanks to everyone for the advice so far!
  7. doesn't matter; 10 ks or 10000ks, you can have a counterweight come off the wheel... but unless it was a 50g countertweight, It's likely not an unbalanced wheel. if the vibrations occurred out of time with the wheel, i.e. Whrrr... half second.. Whrr, then replace the chain/sprockets. If it's clunkclunkclunk or vrrrrrrrr (how's that for onomatipoeia?), I.e. synchronised with wheel revolutions its likely shafted bearings. (/pun)

    Given you suggest chain tightness/loseness was an issue, and it's rhythmic, I'm listing towards the chain being rooted. what's he varience in chain play?
  8. Sounds like chain to me, too. Try putting it all back together and adjusting the chain at its tightest point (may take a few turns of the wheel to determine that point). If in doubt, adjust it a little loose. If the problem goes away its new chain and sprockets time.
    A loose chain is not good but a too tight chain is much worse as it overloads the bearings in the wheel, gearbox and swingarm pivot.
    Note that it is very easy to overtighten the chain if the bike is on the centrestand when you do it. That's because the chain will get tighter when the weight is back on the rear wheel. Ideally adjust it while someone is holding it up for you, while they're sitting on it. Its a bit of a pain to do that while moving the bike to and fro to find the tight spot, but the only way to do it properly.
    I've found with my GS500 that after doing it a few times I can do the adjustment with it on the side stand (so there's still weight on the back wheel) and estimate a few mms extra slack, so that its right when I'm riding it.
    The rusty look on the front sprocket could be caused by it fretting against the shaft.
  9. That was the first thing I did - adjusted the tightest point to have around 30mm slack when on the sidestand. That then left at least 40 or 50mm slack in the loosest part of the chain though - so that would suggest stuffed chain?

    Sigh. Might do a strip-down of the bearings tonight as well as trying to get my head around how to replace the front sprocket. I won't write off the bearings being screwed just yet - when I had the tyres replaced, the front wheel bearings were also replaced as they had rusted completely. :shock:

    EDIT: Another thought - clearly don't do much at work apart from spend time thinking about riding :grin: - would wheel alignment be able to cause that sort of noise? I haven't noticed it 'crabbing' at all, still points straight so I doubt that would be it, but just another theory...
  10. check to make sure the tyre isnt at fault as well
  11. The wiser heads have told you it's the cush drive
    Fix it and ignore all the others :roll:
  12. I betcha it's a rooted chain. That causes a rhythmic vibration, usually you feel it first in the footpegs. If you've already identified that you've got a tight link or two, that clinches it for me.

    You've already checked all the wheel bearings and they're turning totally smoothly, yeah? No gritty feeling, no crunchy feeling, no resistance? If you're sure both sides are fine, chuck some high temp grease in there anyway.

    How old is the bike? How many Ks? I doubt the cush drives are worn out.
  13. On the money. New chain and sprockets sorted the problem.

    An update/resolution, in case anyone goes searching for this again.

    After a week and a half, buying the wrong chain tool, buying the right chain tool, cutting the first chain 2 links short :oops: , bending the tool, improvising the tool to make it work properly - i finally went to start it up, and had to charge the battery lol. :p

    Anyway, just got back from the first ride, and it feels soooooo good - power delivery seems smoother, although that could be my imagination anyhow. The new chain and sprockets have made a world of difference, and i wish i'd done it sooner. forgot to take photos along the way, but i don't think anyone wants to learn how to change it over the course of a week... :LOL:

    Now I'm just going to keep an eye on the tension of the chain over the next few weeks to make sure it doesn't stretch too much initially (should it? i don't know), and enjoy riding again!
  14. :roll:
  15. Well done on fixing the problem. However just a minor point that chains don't stretch but the pins and sleeves wear as well as the sprocket teeth. The major contributer to the chain becoming slack is wear in the individual links. Over the length of 1 meter of chain with 50 links it takes just 0.01 mm wear on each link for the vertical chain slack to increase by about 15 mm. I hate rear drive chains but they are a necessary evil.
    Quality chain, good lube, regular attention. With a non-O ring chain I remove, clean in petrol, then heat on my barbecue in saucepan with HMP grease. The grease melts and penetrates the rollers. I hang over the saucepan to drain excess grease. I then wipe the excess with a rag. The petrol removes the grit that wears the chain.
    I used to do this every time I changed the rear tyre which was every 6 months or 6,000 km. I don't believe in oiling a chain as it's just flings off all over the rear end. If I do occasionally lube the chain while it's on the bike, I use spray Lithium grease while rotating the chain. The solvent penetrates the rollers and carries the grease. The sprocket and chain roller contact points do need some lube but just a little. It might look good to have a well oiled chain but within 100 km most of it ends up on the bike and some on your leg. O-ring chains should last their service life without much lube. If they are out of adjustment range or noisy, they need relpacement. Some solvents will damage the O-rings.
    How long a chain lasts depends on the conditions, the quality of the chain and your riding style.
  16. Fair call. I'm a believer in "dry" (bel-ray, etc) chain lubes - don't attract dirt. All depends who you talk to regarding Oring chains - My only-for-warranty period mechanic was whinging about how Oring chains are crap, they wear out too quickly etc... lo and behold, he WD40s the chains... :roll: