Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Bent shift rod

Discussion in 'Technical and Troubleshooting Torque' started by dbrain, Jun 1, 2016.

  1. Hey!

    I bought a bit of a beat up '91 CBR250RR. Just tearing it down and working out all of the bits that aren't happy and giving it a good clean. Mostly pretending to be a mechanic and learning by doing, hopefully without an [external] explosion of some sort at the end when I try to start it.

    Anyway, one thing I've found, the gear shifting rod.. roughly 20cm, maybe 8mm in diameter.. bit of metal running from the gear lever to the shifting cog thing (official name) is bent. I'm struggling to source a replacement, as it seems to be a discontinued part, and most wrecking bikes rods are also bent.

    Does anyone have any experience unbending metal rods? Is there a DIY way to sort this?
    Is there someone I could take it to to get it sorted?

    It's not bent terribly, gear shifts seem to work (struggle to find neutral, but might be unrelated), but feel like I should sort it out.


  2. Take it off, heat it up and persuade it back into shape?
  3. #3 oldcorollas, Jun 1, 2016
    Last edited: Jun 1, 2016
  4. I doubt you'd even need to heat it. If you mean the rod that connects the bottom of the foot control to the shaft going into the engine. I'd just remove it, put it on the anvil, or any seriously substantial and flat surface (but not a driveway or road) and bang it straight with a hammer, taking care not to damage the threads at each end.

    Providing it is made of steel, it can be cold straightened. (alloy will often crack if you attempt to bend a bent bit straight again, but steel will not. Look at the threads, you should be able to see whether it is steel or alloy (and I doubt it is). A little filing can confirm if it is steel - harder than alloy, harder to file - a couple of strokes on the end would be enough, or even better, check it with a magnet. That's even easier. If its magnetic, it's OK to bend, by whatever means. It won't be high tensile steel and won't shatter.

    If it is chromed and you want to protect the chrome from hammer blows, wrap it in ducting tape. So long as you don't hammer endlessly on it or WAY too hard, a single layer of tape or two will protect the chrome a little. Hammering on chromed parts may dent the steel beneath the chrome and cause the chrome to flake off, usually at a later date, possibly buffer the blows with a little wood. Using a press might be the best, but who has one of them? At any rate, protect the threads because you will want to put it back together. It's worth putting a little bit of something on the threads and the collars that they screw into before you take it apart, like a little bit of nail polish or fast dry paint or even a texta mark so you know how far to wind the threaded rod back in to get the original position.

    This rod gives you adjustment to the attitude of the shift pedal - you might want to adjust this anyway, when you are done.

    Good luck.
  5. As in shove it in the oven or something? Will give it a shot.

    Definitely not meant to be bent, bikes gone on its side at some point and the gear lever has pushed into it

    The rod has one male end and one female, if that's the right wording. Basically threaded on one side and reverse threaded on the other. Otherwise I probably could have just bought a long threaded rod of the right dimensions.
  6. inny and outy? :D

    are they left and right hand threads?

    ie if you keep ends still and rotate the road, do the ends move closer and further apart?
    or you need to rotate each end opposite ways to make the linkage longer?

    and no.. most threaded rod is shit, especially at bunnings :D

    another option is to find any engineering place that has a left hand thread in the size you need (if it does have LH thread) and just make a new rod.. should be cheap, cos it would take 5 minutes

    fwiw, MC22 diagram shows male at both ends... maybe yours is already a dodgy replacement?
  7. I was thinking more towards the blowtorch end of the scale.
    • Agree Agree x 1