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Discussion Starter #1
Has anyone ever had this issue? I did a search, but couldn't find anything with a knock in a specific gear....

I bought this bike with 3k miles and she ran fairly well except for a slight vibration and this 3rd gear knock. The previous owner had paperwork for maintenance all performed at the dealership.

The third gear knock is RPM dependent... it knocks faster as the rpms increase. I can feel it knocking on my pegs and I can hear it. Again, this only happens in third gear, so it doesn't seem like it would be the chain. Is it something in the transmission that is specific to third gear? Is this regular? The oil was just changed prior to my purchase (at the dealership).

If it is the transmission, how hard is it to open the transmission on a bike? I've done a lot of mechanical work on bikes, but nothing transmission related....

Thanks for any help/advice.
 

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To have a look in the transmission you would need to remove the engine and split the cases... something you want to avoid where possible.

Sure its the gearbox and not the cct?
 

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Discussion Starter #3
seems weird that the gearbox or the CCT would go out at around 3k miles....

and if it were the CCT... would it be making the knocking noise only in 3rd gear?.... I would think if it were a CCT issue, it would make noise in every gear, but I'm not sure...
 

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It should make it in all gears... does it do it in neutral?

And even though the bike only has 3k miles, its 4 years old... that is a lot of time to wear particularly if the PO was only doing short runs.
 

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Discussion Starter #5 (Edited)
No, no noise in neutral. Do you think there are any consequences if I don't get it looked at? I could replace the CCT, it is a fairly cheap part... but I'm just not sure if it would fix the issue. Any other ideas? :).

It doesn't seem to effect performance of the bike... still accelerates as it should in 3rd... just the sound and the knocking feeling in the pegs... can't get my head around what it could possibly be....
 

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Discussion Starter #7
if I'm low rpms in 3rd gear (e.g. 3k-4k), it knocks maybe 4-7 times per second and as rpms increase, the knocking increases until you can barely tell its there.

I should get a video.... I had my friend ride beside me and he said he could hear it too... but we are both stumped on what could cause it only in third gear.....
 

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a video would be awsome if you can kill the wind noise

(suggestion, piece of electrical tape over mic opening is great and killing wind noise)
 

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Discussion Starter #9
btw Nico, does your name come from the Nissan forums? I used to be fairly active there, but switched to miata's for a while...
 

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Sounds similar to a problem I read about on cbrforum. It was the transmission, i'll see if I can find it and post a link.
 

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Discussion Starter #12
I'm hoping it's not the transmission. Scared me for a bit! :p. I'll get the video and post up this weekend. Thanks guys.
 

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I'm hoping it's not the transmission. Scared me for a bit! :p. I'll get the video and post up this weekend. Thanks guys.
Sorry for the scare, hope u find out what it is n It's a nice n cheap, easy fix, if there is such a thing. Good luck.
 

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Discussion Starter #14
I finally got some vids of the issue. Kinda just held the camera by hand... and velcro'd it to the the triple tree just in case I needed my other hand in an emergency.

Here's the links:

6822:

6823:

1st video (6822), I am in 3rd gear and I stop at a stop sign, so I switch back to 1st. Start at 1st, hit 2nd (no knocking in these two) and then in 3rd again, you'll hear the knock.

The 2nd video (6823) I start from a stop in 3rd gear and it's knocking pretty noticeably at such low rpms. I probably hit around 5-7k rpms in 3rd gear and then pull in the clutch.

After re-listening for this issue, I think there is a slight knock in 3rd gear even when I pull in the clutch... very minor....
 

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Sounds to me like a broken tooth on the third gear. I would pull the exhaust and oil pan off and take a look. Pay special note to what u find when draining the oil, and inside the oil pan.
 

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Discussion Starter #18
Any advice/manuals on how to pull the transmission? A google search has found nothing :-(.

I recently changed the oil and didn't see anything unusual. I wasn't specifically looking for anything at the time though... but we double pour from a catch pan into a large container and I think I would've seen something on the double pour....

So... bearing or tooth? Either way I need to pull the transmission?

I've never dealt with transmission issues other than just changing fluids in a car... so, are there repercussions to riding with this issue? I'm guessing this is also what's causing my vibrations... heh
 

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Any advice/manuals on how to pull the transmission? A google search has found nothing :-(.

I recently changed the oil and didn't see anything unusual. I wasn't specifically looking for anything at the time though... but we double pour from a catch pan into a large container and I think I would've seen something on the double pour....

So... bearing or tooth? Either way I need to pull the transmission?

I've never dealt with transmission issues other than just changing fluids in a car... so, are there repercussions to riding with this issue? I'm guessing this is also what's causing my vibrations... heh

you are going to have to pull the engine, and open it to get to the trans

repercussions ... could be none, or you could end up with a seized transmission while your doing 75 mph down the highway causing your back tire to instalock and possibly throw you off the bike .....
 

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^What he said...

Repairing a transmission is not really something I would reccomend to the beginner... there are a lot of parts there to get in the wrong way around / aligned incorrectly and some experience needed to recognise things like damaged thrust washers etc...
 
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