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General question: Why is first gear so loud to engage when stopped?

Discussion in 'Technical and Troubleshooting Torque' started by grue, Feb 7, 2010.

  1. I've always been curious but usually forget to ask by the time I get home ](*,)

    It's been like this on every bike I've ever ridden. Engage first, it's always a nice solid THUNK

  2. Some are louder than others.
  3. I've often wondered this too, Grue. Maybe something to do with neutral being above first? Just a guess.
  4. my r1 is like this its a 99 model with 15000 kms in pristine condition -- just an idiosyncrasy i guess
  5. One of the nice things about the much maligned BMW gearbox is that it's possible to feel first home almost silently. Unlike the violent metallic thwack that the DR produces, no matter how much I fuddle with clutch adjustment and idle speed.

    Come to think of it, I don't remember too many of the older Jap boxes being quite so unpleasant going into first either, so it seems to be a feature of modern gearboxes.
  6. Maybe it's something to do with running engine. In neutral, on my bike stand, the wheel still manages to turn. So maybe something is spinning and when you engage first it slams into place. Meh...
  7. it's because the gearbox in pretty much all bikes is a "dog engagement" gearbox. this means there are no synchro's to make changing gears easy, including going into first from neutral.

    put basically, you have a spinning metal chunk colliding with a stationary metal chunk... it makes a bit of noise when u engage them.

    just make sure you are firm with shifting gears AND putting it into 1st from neutral. if you pussy foot around u can gear the doog teeth grinding against each other.. this isn't good.
  8. Sheppo's closest.

    Sequential gearboxes are constant mesh, meaning the gears are always engaged only transferring power based on how the dogs are engaged. Sooooo, there you are stopped at the lights, in nuetral, clutch out, which means that the engine is spinning the input shaft of the gearbox. The shaft is still spinning under it's own inertia when you pull the clutch in and you snick in the gear which slams the dogs into engaging a stationary output shaft. CLUNK.

    The thing mentioned by Mr Messy is oil drag, usually only when the oil is cold and viscous. Some bikes are much more prone to it.

    Starting a cold gpx250 in gear but clutch in is sure to see the bike move from under you when the starter motor kicks in. You soon learn to hit the start button with a brake applied!

    The track stand wheel spin thing is a cold oil thing too - oil drag between spinning output gears and the output shaft.
  9. The old man once told me to push my bike forwards when I put it into first so the bike is rolling a little when it is engaging. Low and behold the clunk isn't anywhere near as big.

    I've now worked out a method of rolling the bike forward a half a meter to a meter or so very slowly and when I put it into first all I hear is a click. Obviously pushing your bike a meter at a set of lights isn't what you want to be doing all the time but a small push forward helps, and the meter roll out the driveway to and from work makes for less clunk at least twice a day.