gearbox knocking under acceleration.

[Ben sIII]

Hi all,

So my bike has very rapidly developed a loud knocking sound whilst accelerating under load. I can't replicate this with the bike in neutral, or running it in gear on the stand. I was hoping someone has experienced this before and worked out the cause.

 

[ChanceCoats123]

How does your chain look, and how did you determine that it's in the trans? It only happens under load, so it could be as simple as some stuck links in the chain.

 

[Ben sIII]

Thanks for the reply cc, went through the chain, it's in spec and no stiff links or signs of wear. Only reason I say GB over engine is that I can have the sound, pull the clutch and sound goes, also an excellent way of cancelling out the chain sadly. Not sure if it's the clutch basket, bearings or even stepped teeth, though the knocking sound confuses me. , Just hope someone knows before I start pulling it apart.

BTW 06 fzs, 42000 kms

 

[TownsendsFJR1300]

As posted above, the chain is most likely your issue. It needs to be well lubed/maintained/ajusted correctly.

I know you inspected it, however what you desrcibe is a classic failing chain..

IMO, I'd invest in a new chain (and sprockets if slightly worn) before opening up the engine. If it doesn't work, you have a spare chain (or sell it, it will move).

And just as a side note, I've had issues with a DID X chain (o-rings failing-extremly well maintained). I'd stick with a regular O-ring (but name brand chain)

And lastly, and MOST IMPORTANTLY, 2" of total up and down play measured at its tightest point is CRITICAL...

**You may want to pull the front sprocket cover and watch as the chain comes off the sprocket. If there's any binding, it'll show up there...

 

[Ben sIII]

Thanks Scott, sadly after much searching through the forum, it appears to most likely sound like the gremlin videos of metal throughout the transmission. Bike is due for a service so will drop the pan anyway and investigate.

Cheers,

Ben

 

[TownsendsFJR1300]

Thanks Scott, sadly after much searching through the forum, it appears to most likely sound like the gremlin videos of metal throughout the transmission. Bike is due for a service so will drop the pan anyway and investigate.

Cheers,

Ben

Good luck with it Ben and please post what they find.

Just as a side note (a good side note), most if not all those mysterious noises were due to a failed clutch and the remnants getting crushed in-between the crank grear and clutch basket. And those noises were present most of the time...


Some troubleshooting tips if you have time to kill (it'd help the tech too);

(1)Try riding the bike in an area W/O a helmet (Of course be carefull) and where its quiet and see if you can ascertain if its coming from the engine itself, wheels, right side or left side more predominatly.

(2)Also, try and nail down what gears its most noticable in.

(3)If the shop your going to has a dyno, I'd put the bike on there first before pulling anything. The half hour or so on the machine should help pin point down the area/gear too... (If that's the original chain with 26,000 miles on it, its still high on my list)


I have to doubt its something seriously wrong, but again good luck...

I'm assuming nothing important happened you didn't mention just prior to the noise??

 

[FinalImpact]

Good luck with it Ben and please post what they find.

Just as a side note (a good side note), most of not all those mysterious noises were due to a failed clutch and the remnants getting crushed in-between the crank grear and clutch basket. And those noises were present most of the time...

I have to doubt its something seriously wrong, but again good luck...


Randy? [MENTION=15974]FinalImpact[/MENTION]

I've been watching and it seems like a chain issue to me. As noted, clutch bits through the primary gear reduction set (crank & clutch basket) and the noise is 100% and IT never goes away!!

If in doubt about the box, dump the oil into clean pan and look for bits. Hack open the filter and search in the pleats for bits. I've done it on every USED vehicle I ever bought on the first oil filter just so I know its rate of loss. If they come on clean the next go around, I quit looking.

To my knowledge no one has ever killed an FZ gear box either. They may make noise, but they don't fail. One guy hit two gears at once under load and it made some noise. i.e. likely deformed the lead babbit bearing in a gear making an odd noise under load in that gear.

Click link or image; How too - Cut open oil filter...



How long has it been present?
Does it change pitch, sound, loudness if the oil is changed?

If you Point your LEFT knee STRAIGHT OUT, is it LOUDER than when you point your RIGHT KNEE Straight out? At speed obviously...
If so, I'd be more suspect of the chain!​

 

[Ben sIII]

so a quick update,

being the season, i have had little time to play with the bike and have a look, and australia being what it is, our local dealers and parts centres dont hold stock, though they complain about people buying their parts online and overseas...

anyway, as i stated before the chain is in spec and i couldnt notice any stiff links, though i took the rear wheel off today and worked through the chain link by link and found a few tights ones, most i could loosen with wd40 and working the link though a couple stayed stiff. as a result the sound seems less to me so hopefully that was the issue and a new chain may be in order.

Will still pull apart the clutch for my own sanity when i get the new plates and gasket, 45000 km so may be getting near the time for a new one anyway.

on a quick note to answer the questions, about 1000kms ago i snapped the clutch cable 100km from home so rode it without a clutch to get it there, most of the changes were fine though 1 or 2 sounded a bit rough going down to second. this made me maybe jump to considering the gearbox a bit early.

thanks all for the help and will continue to update.

 

[TownsendsFJR1300]

Thanks for the update.

You just answered likely most of your issues. ANY links sticking will cause issues. Getting most of them out will help however, the chain is telling you it needs replacement.

WD40 is probably ok for straightening those links/ cleaning, but if its being used as chain lube, DON'T... Its not designed to be a MC chain lube. If MC specific chain lube is NOT available, USE ENGINE OIL as your owners manual specifies (messy but better than WD40)

Re the clutch, its easy enough to change out but un-less you seriously abuse it AND its NOT slipping at all, it should be fine.

Good luck..

 

[Ben sIII]

Thanks Scott.
It's OK, the wd40 was only to try to free the links, thinking pressurised kerosene in an easy to use package. Proper chain lube was liberally used after.

New chain and sprockets are on the way. On a side note, the sprockets are still good though I don't see the point of changing the chain and not the sprockets. Does the fz6 have a special front sprocket with some form of seal or anything I'm not aware of, or am I OK to get an aftermarket one?

 

[TownsendsFJR1300]

On a side note, the sprockets are still good though I don't see the point of changing the chain and not the sprockets. Does the fz6 have a special front sprocket with some form of seal or anything I'm not aware of, or am I OK to get an aftermarket one?

The OEM sprocket has a plastic(maybe) type coating just below the tooths edge. I'm guessing it to keep noise down but no, you can use an aftermarket sprocket W/O issue.

Just make sure if the aftermarket sprocket has an offset on ONE SIDE ONLY, its re-installed in the same position as the OEM sprocket. (I wouldn't go with aluminum/something soft just for lack of longevity)

There's nothing special under the sprocket although it is tight (65ft lbs). I would clean it good before removing the ft sprocket.

Depending on the year bike, it either has a separate fold over plate locking the nut or the nut itself gets peened slightly on two sides(S2).

With the chain still on (and properly tensioned), I used an air gun to remove that nut(in neutral). For re-installation, I padded a steel bar and jambed up the rear wheel with the swing arm, tightened up the new chain some and torqued the ft nut. If you have another body to help, they can hold the rear brake activated and should hold the rear wheel tight enough to again torque down the ft sprocket.

Make sure the rear sprocket studs are spotless CLEAN, (no oil/lube, etc) and tighten in a criss cross method. The manual calls for 72 ft lbs (a bit tight IMO) but it should take the torque. Torqued "criss cross" like a car wheel... **Oil/grease on those studs will almost gaurantee a sgripped rear sprocket hub stud**.
An interesting read; http://www.600riders.com/forum/garage-mechanical-help/53487-rear-sprocket-carrier-failed-studs.html

 

[TownsendsFJR1300]

Any updates???