Author Topic: Bent gear shift roccker shaft?  (Read 621 times)

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Wombat

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Reply #15 on: September 15, 2021, 12:39:18 am
I'm hoping someone may have an idea of what is going on with this?  Downshifting was all good before the rocker shaft got bent, so presumably something else may have been bent further up the line.  Pretty sure the bike was in first gear when it fell over, but could possibly have been second.  If something else was damaged up the line from the rocker shaft, and ideas on what the most likely candidate could be to cause false neutrals downshifting from 3rd to 2nd gear?  Could it be the neutral finder cam plate or shifting forks?

Thanks in advance for any advice or suggestions.



Mad4Bullets

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Reply #16 on: September 15, 2021, 02:32:26 am
It must have taken quite a hit to bend the assembly as it did.  It's possible that another less robust stamped part of the assembly where the springs attach could also be bent or misaligned, but you'd have to take it apart once again to inspect the entire assembly, and even then there are no guarantees. If it were me, and mind you I'm cheap as hell, I'd order the new gear change assembly and replace it as suggested by others. But that's just me. It's a touchy mechanism.


Haggis

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Reply #17 on: September 15, 2021, 10:59:37 am
I have a sneaky feeling it could be a bent selector fork.
Difficult to tell without a full strip down and split the cases to visualise the actual parts.
The only bits you can get to from the outside, you have already been there.
When you shift from 3 to 2, are you going past 2 and into neutral proper or are you finding a false neutral between 3 and 2?
Meaning 2 is not being fully selected.
« Last Edit: September 15, 2021, 11:03:10 am by Haggis »
Off route, recalculate?


Wombat

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Reply #18 on: September 15, 2021, 07:32:52 pm
Thank you  both for your replies.  As I always I am very grateful.

I've ordered a new gear change assembly and will install as soon as it arrives.  I guess there is a chance that alone will make a difference, but I suspect something more will also be required.
 
Symptoms are:
It appears to be shifting from third past second to actual neutral.  If I stop at that point, the neutral light is on and the bike rolls with the clutch out.
If I shift up again from that neutral position it engages second.
When the bike goes into neutral after downshift from 3rd to 2nd, the bike will not shift down to first from there.  It will however shift easily back up to 2nd, after which it will shift down to 1st normally.
My workaround while riding for now is to downshift from 3rd to neutral, and them immediately up to 2nd and then back to 1st when stopping or otherwise requiring 1st gear.
Neutral can be a bit difficult to find from 1st gear.  It's easier to go up to second and then move back down to neutral

Haggis, your suspicion regarding the selector forks is probably correct.  Based on the symptoms do you still have that sneaky feeling?  If so, do you have a hunch about which fork is most likely to be bent?

Cheers


Haggis

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Reply #19 on: September 15, 2021, 09:45:21 pm
This the bit you can get to from the outside, that you straightened.
I would hope that your replacement part will fix your problem as there may be other twists or bend on the damaged one.



The rest is on the inside and requires a full engine strip to get at it.




The notches in the camplate are each gear position.
A bent selector fork would move the gear more/less than it should.
Do you still have a positive click from gearbox as each gear selects.
Engine off is fine but you might need to jiggle the back wheel a little .
« Last Edit: September 15, 2021, 10:09:24 pm by Haggis »
Off route, recalculate?


Mad4Bullets

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Reply #20 on: September 15, 2021, 10:31:00 pm
Here's a video that offers a rare insight into the gearbox and its actuation. I believe this will be of interest to anyone who is trying to help you solve your problem.  It's very enlightening. Enjoy.

https://www.youtube.com/watch?v=4xgvtWbPviA


Mad4Bullets

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Reply #21 on: September 16, 2021, 03:11:01 am
Another possibility is that some other bend or misalignment in the overall shifter assembly may be resulting in a slight over-rotation of the shift cam plate when shifting from 3rd to 2nd.  As a result, the spring-loaded anti-skip mechanism shown in pink may not be fully seating as intended in the detent on the outer profile of the shift cam plate. All speculation mind you, but you'll know soon enough when you replace the shifter assembly.


Wombat

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Reply #22 on: September 16, 2021, 04:28:56 pm
Thanks again guys.  Your responses are GOLD, and that video is great.  Provides nice insight.

Haggis, yes I get a positive click when I select gears. 

Mad4Bullets, thanks for your advice.  I wasn't aware of the anti-skip mechanism and I like the idea of what you're suggesting.  I'm not confident enough to strip down the engine to get to the shift forks etc, so if it gets to that point it will be a trip to a dealer.  The nearest is quite some way from here, and cost may be prohibitive so definitely hoping not to have to need that.

I'm hoping that as you both suggest, replacing the damaged shift mechanism will take care of the problem.  I think the best thing now is to just wait for that to arrive and reassess once I have that installed.  Fingers crossed that takes care of it.  I'll update here once I get to that point and know either way.

Thanks so much.


Mad4Bullets

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Reply #23 on: September 16, 2021, 04:58:12 pm
Yes, fingers crossed. Looking forward to a positive result.


Ove

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Reply #24 on: September 18, 2021, 07:55:16 am
Have you ruled out any denying of the cover around the Bush area?


Wombat

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Reply #25 on: September 18, 2021, 03:01:18 pm
Have you ruled out any denying of the cover around the Bush area?

I'm not quite sure what you mean by this. Are you suggesting the housing around the black spacer on the end of the gear change shaft could be damaged?  If so, no I've not considered that. I'll check when I pull it apart to install the new rocker shaft. If that's not what you meant would you mind clarifying a little please.  I'm open and grateful for any and all suggestions and possibilities.  Thanks.


Ove

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Reply #26 on: September 18, 2021, 11:01:04 pm
Sorry, auto correct got the better of me. "Denting", not "denying". I was wondering if the gearshift side could be pushed in allowing the opposite force to rearrange the Bush end? Just a thought.


Wombat

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Reply #27 on: September 19, 2021, 01:08:52 am
Aha.  Now I get it. I don't think that has happened. The gear lever side all looks good. Worth checking though.  Thanks.