Noise/feeling on final drive

[adamhearn]

Further to my poor running (Fuel system thread) my L4 also has a problem with the final drive somwhere.

After the bike is used for a few miles I feel a knock/graunch/something from the drive. I can hear it but it's not a knock, more like a feeling through the footpegs.

I think I can only feel it when off the throttle but in gear. It could be present when on throttle also but it's more difficult to discern so my mind may be blanking it or even making it up Also, importantly [and I assume badly in terms of possible expense for repair] is the noise/feeling isn't there when I pull the clutch in.

The chain was ran with it adjusted too tight for a while and is now a little slack apart from one tight spot. It could be the chain and I'm open to that but that wouldn't explain the noise disappearing when I engage the clutch.

When I was last at the bike garage no obvious issues were seen - it passed it's MOT but wasn't taken on a ride.

Has anyone got any suggestions for me to look at - I'm not a mechanic mind you!!

[CaNsA]

Sounds like you have a tight spot on the chain.
Get the butt up on a paddock stand, stick the bike in neutral and spin the wheel slowly by hand. You DO NOT need the engine running!
When looking on the lower half of the chain, the part under the swingarm, it might move up and down.

A new chain and sprocket set isnt that pricey.

[adamhearn]

Wouldn't a tight chain always be heard/felt whatever the clutch was in or out? I'm convinced the issue is only present when the clutch is engaged.

I will get the bike on a stand and see if it's worse than I'm remembering.

Thanks for the reply!

[CaNsA]

Not a tight chain, but a Tight Spot.

It is a link on the chain that has seized and doesn't rotate on its hinge.

[adamhearn]

Sorry for misreading/understanding, will look this evening.

[adamhearn]

I didn't notice any tight links though the chain was worse than I recalled! The tight section was quite noticeable so it's got to be replaced [with sprockets] anyway. Hopefully the problem is related to it and I don't find anything else more expensive.

[CaNsA]

If you are feeling a knock knock knocking through the pegs the chances are its a buggered chain.
Also, while you have the back wheel off check the cush rubber. It is probably buggered too.

[adamhearn]

Chain & sprockets ordered. Will look at the cush rubber when I take the wheel off. How do I know if it needs replacing?

[CaNsA]

Trust me, you will know
It will look really really worn on one side.

with the bike on the sidestand, go and try to move the rear sprocket by hand.
If it rotates more then about 0.5mm, maybe 1cm, then it will need replacing.

[adamhearn]

No movement by hand.

Here's a couple of pics of the cush rubber. Looks OK [to me it does] though this is some wear shown in the second picture on the outer edges - where the metal is shiny on the sprocket carrier:


Front sprocket (new one has been ordered to go with chain). Does the sprocket holder generally look like that [not slotted fully into teeth]?


To get the sprocket off the carrier it's just a case of brute force with a breaker bar. No movement thus far and the rubber was flexing so thought I'd ask before destroying something!

Thanks in advance!

[CaNsA]

Cush rubber looks not to shabby mate.

It's easier to "crack" the nuts while the wheel is on the bike.
The front sprocket retainer should look like that mate.


Good luck, dont f*** it up

[adamhearn]

Sprockets are now off

The front one is actually quite worn (shark teeth) but the rear one not so much. Bike looks a bit sad on the stand missing its drive but I've taken the opportunity to clean all the crap off.

What everyone's view on [not] using a torque wrench when putting the parts back? Lots of web research suggests I need to spend pretty big money to get something that's accurate and then I'd also need to buy two given the range of bolts that are off the bike If I "must" use one, feedback on what's cheap but reasonably accurate appreciated!

Also, what grease should I be using on the rear axle when rebuilding? I've got a [very old] tub of Castrol BNS (my general use for all conditions grease) but will grab different as suggested.

Thanks in advance!

[CaNsA]

I hope you aren't planning on not swapping the rear sprocket.....

Torque wrench - I havent got one, i use a bit of common sense

Grease - Marine grease, but any decent stuff should do.

[banner001]

i have two torque wrenches...if it says to torque it...i torque it.

i have a sealey one thats 2-26nM and a teng thats 19-110nM, i will be getting another one thats 80-300nM to do clutch nut and anything else that requires it.

looking at ~£70 for my two wrenches.

[adamhearn]

Thanks to you both for your replies. Whilst I have previously used "judgement" in this area, I'll ask around at work to see if I can borrow one as I'd like the final drive parts to be back on as they should be. I may end up on Amazon for a smaller one (like the Sealey) as that range would be useful for my bicycle too.

I hope you aren't planning on not swapping the rear sprocket.....

Don't worry, I might not be a bike mechanic but know they all need to be replaced at the same time.