Trouble with chain alignment and tensioner stability.

Discussion in 'Transmission / Drivetrain' started by BlueDestiny, Dec 17, 2014.

  1. BlueDestiny

    BlueDestiny New Member

    I am having some difficulty getting the drive chain to fit properly. The problems are a huge amount of vertical play and the tensioner wheel being pulled sideways into the spokes.

    Here is a picture of the vertical play. As you can see the chain goes way up and down, but despite that I can't seem to make it any shorter and still fit the tensioner.
    uneven tension.jpg too loose but no room to shorten.jpg

    Here I've tightened it as much as possible with just the tension pulley. It worked OK without the clutch.
    pulled taut.jpg

    But as soon as I engage the clutch and turn the wheel, it falters and yanks the pulley sideways, forcing the chain to rub against the tire.
    pulley yanked sideways.jpg

    The chain itself doesn't rest evenly on the pulley wheel, which might be causing it to pull inward.

    Instead of being inline with the groove on the pulley like this: |I|

    It sits at a slight angle like this: |\|

  2. Slogger

    Slogger Member

    You can probably take a link out of the chain since it's so sloppy. The tensioners are always needing attention, mine is bent to a sort of an S shape to get it squared up under the chain right.
    Using some blue loc-tite on the nuts and putting a coat of plasti-cote on the frame under it should keep it out of the wheel.
    Hope this helps, good luck to you!
  3. tomtruty

    tomtruty New Member

    Please reconsider using the chain tensioner on the drive chain. Remember the top chain in under tension when the engine is pulling your bike. When you decelerate or start your engine the bottom chain is under tension. If your engine kicks back your spindly tensioner will bend into the spokes and cause big problems and possible physical pain! Spring loaded tensioners don't work well unless there's very little action and even then the chain is liable to pop off when you start your engine. Adjust the chain length as close as possible without tensioner. You may need a half link to get the pedal chain somewhat tensioned when the drive chain is right.
  4. BlueDestiny

    BlueDestiny New Member

    Thanks for the replies. I'll see if I can ditch the tensioner and manually adjust the chain using the little bracket space things (walkouts?) in the rear wheel fork.
  5. bluegoatwoods

    bluegoatwoods Well-Known Member

    You definitely want to shorten your chain. It's much longer than it needs to be.

    tomtruty is right in suggesting a half-link in order to get both chains tensioned properly. But there's another way. Shorten your engine chain until it's perfectly tight without a tensioner. Then use that chain tensioner on the pedal chain. It'll need to be hung upside down on that side, pushing downward on the bottom chain run.

    You can get a rivet extractor from some of the vendors that you'll find on the left side of these pages. I believe carries them. If not, one or two of the other sponsors will.

    Or you can always cut (but not lengthen) a chain using a bench grinder to grind off the rivet head. Then just punch the rivet out.

    And if you do overcut it, then you could always get a bit more chain and master link from a sponsor. Then your bike chain will have two master links and you can add or subtract a small chain of links in between.

    I just cut a 415 chain the other night using a bench grinder. I wish I'd taken photos. But if you need that kind of help, then please feel free to come back here and say so. I'll cut a piece and take pics.

    You would need to actually say so, though. For all I know you already know how to do this. Without being told that you need it, then I'll be doing other things.
  6. crassius

    crassius Well-Known Member

    First, you need the tensioner to feed chain EXACTLY straight onto bottom of rear sprocket - turning the wheel should place the chain such that the teeth are right in the middle of the rollers. Next, you need to bolt the tensioner tightly to the frame. Some times the frame is a bit too small for a good grip on it, so I take an inch or so of old handlebar and cut it lengthwise into 2 "C" shaped sections to put under the tensioner mount (these can also help to move tensioner so it is straight by putting both on a side where it is needed. Sometimes, I also need to replace the two 4.8 chinese bolts with two 10.9 or 8.8 american bolts to get it really tight.

    I've done hundreds this way & all work well.
  7. dougsr.874

    dougsr.874 Active Member

    Chain is way too long....take out links....also picture if so dark I can't tell...but it appears that rear sprocket is dished should be dished OUT to keep chain off of tire...
  8. butre

    butre Well-Known Member

    throw away that stock chain tensioner and buy or make one that bolts to the engine. those things are dangerous, and I'm surprised nobody has gotten killed over them yet. If I was in traffic when mine went I probably would have been.
  9. crassius

    crassius Well-Known Member

    I've tried some near the motor, they don't steer chain straight enough onto rear sprocket.
  10. BlueDestiny

    BlueDestiny New Member

    I'll be damned, you're right. The sprocket is dished inwards which would explain the chain running at an angle and throwing the pulley off. The chain just barely clears the frame with no tensioner, so it might be better to attach it to avoid damaging the bike.

    Now all I have to do is re-lengthen both chains, flip the sprocket and try not to have an aneurysm because this is the fourth time I've taken off and removed the darn thing.
  11. dougsr.874

    dougsr.874 Active Member

    If chain hits bike frame after you dish out the sprocket.....then add some washers between the frame and sprocket...this will set the bike frame farther away from the engine chain....
  12. butre

    butre Well-Known Member

    they shouldn't have to steer the chain anywhere, you should have a perfectly straight line between the sprockets
  13. bluegoatwoods

    bluegoatwoods Well-Known Member

    We feel your pain........

    It's happened to me. You can bet on that.

    And I'll bet it's happened to everyone reading this thread.
  14. crassius

    crassius Well-Known Member

    In 6 years of working on these I don't recall ever seeing a totally straight run between sprockets.
  15. butre

    butre Well-Known Member

    I used a manic mechanic adapter to get a perfectly straight run, using a laser line level to be 100% sure it was perfect.
  16. dougsr.874

    dougsr.874 Active Member

    Sometimes you people just amaze me.
  17. crassius

    crassius Well-Known Member

    I refuse to build a coaster brake bike, so that over-priced adapter is not used here.
  18. BlueDestiny

    BlueDestiny New Member

    Flipping the sprocket so it dished outwards helped, but the chain is still misaligned in the pulley and it simply goes for a few more revolutions before slipping and pulling the chain half-off the sprocket and into the tire again. I tried running the chain without a pulley, but even at maximum tension on the bottom half, it still rubs against the bike frame where the tensioner would be mounted.

    The only two things I can think of now are either making an angled pulley somehow, or finding a way to fix the pulley bracket to the frame so that it won't slip at all.
  19. darwin

    darwin Well-Known Member

    IF you use a tensioner please use one that attaches to the chain stay and the seat stay, attaching to only one stay is a disaster waiting to happen. Use a long stick/metal rod if needed for alignment check if eyeballing doesn't work.
  20. crassius

    crassius Well-Known Member

    two other things can be done if you're not up to getting it right as I explained above

    one is to grind or file the sides of the teeth of the rear sprocket so that they are sharp as knives - this way they'll more easily find the gaps in the chain links

    the other is to attach a long piece of metal to the top of the tensioner, then bolt that piece to the upper part of the frame so the tensioner cannot move in/out