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Rear wheel reinstall problem

Discussion in 'Technical and Troubleshooting Torque' started by Viator, Jul 31, 2011.

  1. Hi guys

    Today I changed and balanced my rear tire but I can't get my rear wheel reinstalled properly. The problem I have is that when I run the bike in 1st gear on the paddock stand, the chain sounds real clunky. When I press the rear brake to slow things down, the chain gets worse and starts slapping around all over the place really violently.

    Possible causes?
    - wheel/sprockets are not aligned property i.e spacers missing or not on properly
    - rear brake is dragging
    - rear sprocket or disc was damaged
    - poor wheel balance

    I think I need to address the rear brake first and foremost. The wheel doesn't spin very freely in neutral and the brake pads don't sit flush on the disc. When I put the wheel back in, I levered the pads apart with a screwdriver so I could fit the disc back in, but even after pumping the rear brake, the outside pad and piston haven't come back into the disc properly. How do I fix this?

    I'm starting with the rear brake because:
    - chain slack appears fine
    - I believe I've put the spacers in correctly
    - I can't remember damaging the sprocket or disc
    - the alignment adjusters on each side are the same
    - I think the wheel is fairly well balanced

    Help please! I can't ride my bike :(

    Below is a diagram of the wheel.http://www.kgrant.co.uk/Data/Parts/REAR%20WHEEL%20&%20CHAIN.gif
  2. What sort of bike is it? I got from an earlier post that it's a 900 but not what sort.

    I hate to sound like Brains from the thunderbirds here, (because that's a bit what I'm like) but that's such a vague description it could be just about anything. Do you have a camera phone? Does it record even very ordinary video? Could you arrange like a 5 ~ 10 sec clip?

    Can I ask, how much slack is in the chain? Because re-reading that a few times it sounds like the chain is way too tight. There should be between 20 and 30mm vertical slack mid way between the sprockets, at the tightest point. The problem with the rear brake and the pads not pumping back up may be related or it may be an entirely separate issue.
  3. If you run the rear wheel up when the bike is on the centre stand, it will absolutely rock and buck all over the pace at certain RPM even if everything is OK.

    You need to fix that rear brake first, take it off, clean everything, in particular the slider pins (may be under rubber boots). Then it is really all about wether you are a doofus or not,... ie forgot a spacer or balanced the tyre wrong. Throw an eye down the length of the chain, are the sprockets paralell?

    I get the feeling you are seeing the natural imbalance that you get when runing the bike with the rear wheel off the ground. It does seem very bad, but is usually quite normal.


  4. reads like the rear wheel is not aligned. don't trust the marks on the swingarm.

    To get the pistons back down, wedge something between one of the pistons and the disc. Pump away. When the others are down, remove the wedge and pump some more.

    I don't think the brake is causing the problem. I'd say our wheel is out of alignment. the noise is the chain trying to climb off the sprocket.

    Also make sure you haven't over tensioned the chain.
  5. Thanks for the suggestions.

    The bike is an 00 ZX9R. Chain slack is at least 2cm so I think it's a sprocket alignment issue. I'll run the bike with the caliper off and come back with what I've found.
  6. Don't know the slack for that bike specifically but that seems tightish to me. Also check the procedure for your bike. Whether it needs to be done on the side-stand, upright or with the wheel off the ground.
  7. So I managed to fix the rear brake issue with a bit of fiddling but turns out I've let the battery run flat :( Looks like I'll have to wait a couple of hours before I test it.

    The way I tension my chain is:
    - raise the rear wheel
    - engage 1st and rotate rear wheel backwards until the top of the chain is tight
    - halfway along the bottom of the chain, push upwards and take a measurement
    - push downwards and take a measurement
    - subtract 1st measurement from 2nd to get roughly 25mm of play

    My bike is suggested to need 20-35mm of slack.

    I'm thinking that I had both the chain and the axle nut too tight so I'm going to run the bike with them much looser and see how that pans out. I've obviously made a silly mistake somewhere but it has me stumped because I've never come across this before.
  8. OK you need to check if raising the rear wheel is right for your bike when setting the chain. I'd say most bikes it isn't (at a guess).

    Secondly, "the axle nut too tight"? The main axel nut should be one of the tightest nuts on your bike. Hope you mean the adjuster screws.
  9. Okay so ... I put the bike on the stand and fired her up. Same issue with a marginal improvement.

    So far I've set the rear calliper and set chain slack at 35mm (bout as loose as it should go). Considering everything looks fine I thought what the heck and took it for a ride. My initial thoughts were that the bike felt and acted the same as before I changed the tyres. The rear didn't feel unbalanced and I couldn't tell if it was out of alignment.

    Maybe my slap happy chain was just a symptom of running the bike while the rear was in the air? It makes sense because the top of the chain would have no drag on it when the rear is raised. Maybe I should just listed to the sticker on the paddock stand and leave the engine off when raised?
  10. ibast, I definitely meant the axle nut. I know it's supposed to be somewhere around 100nM but I'm pretty sure you don't want it too tight either. I'm sure it would transmit pressure through the swing arm, onto the spacers, and onto the wheel creating some friction/resistance.

    As for the chain slack, it seems to be the same whether I measure it on the stand or off. I might have a go at checking the rear wheel alignment using string from the engine mount in the frame to the swing arm.

    Thanks for the help so far.
  11. the wheel runs on roller element bearings. Tightening the nut will only effect the inner race and won't effect the way the wheel spins.

    That's a pretty good check.

    My money is still on alignment. Are there any external wheel spacers? Do you have them in the right way?
  12. You can definitely overtighten any bolt/nut of any size, however if you are not using a huge bar or unless you are a weakling just do it up as tight as you can. Once you tighten it up, there is effectively metal spacers all in compression, going all the way through the axel to stop you from putting too much pressure on the side of the bearings. The bearings will likely be deep grove ball bearings, not rollers.

    Thanks karl for pointing out that the violent rocking is normal if you run your bike with the wheel off the ground.

  13. Lol, I was just getting on here to say thanks Karl but you beat me too it.

    So I guess I've learnt that I never really had a problem in the first place. I went for a spin up to the shops and the bike runs great. Can't wait to try and wear those chicken strips off the tires. Apparently I need well over 50 deg of lean to reach the edge of these pilot powers.

    Join me on next weekend's episode when I attempt to set the valve clearance :eek:hno:
  14. No worries. Checking the valve clearance is relatively easy. Pulling the Cams is also easy. Getting the shim right is all about taking a deep breath and working it through. Do not drop em in the crankcase!. Putting the Cams back in can be tricky if you stuff up the timing. I get a permanent marker and mark which tooth matches which part of the chain before I disassemble. Then Torque the cams back down carefully. Crank the engine a bit and check the clearances again.
  15. Yea cheers. I've played with cams, shims etc before and it wasn't too hard. On the other hand, I've removed a rear wheel before and yet here we are.
  16. When you pull the cam covers, carefully put a rag over every hole into the bottom of the engine..
    if the cam spockets have a hole in them, wire the cam chain to the sprocket so it cant move anywhere, works on some bikes, not on others so its a judgement call.