Grinding / Grating over Bumps

[Guest SlinKO PLuSh]

Hello all,

 

I'd appreciate your input on a issue i've noticed over the last few weeks, whereby the bike makes a grating/vibrating sound/sensation through the seat  momentarily when I go over road imperfections at around 60mph plus; it's when the suspension compresses and feels like a vibrating/grating sensation which is quite disconcerting, as if the suspension is bottoming out or something is catching when the suspension goes through it's range of motion; the bike isn't overly laden, just me and and my 12 stone. 

 

Have 10,000 miles on the bike, chain is the correct tension and new chain/sprocket set was only fitted by Honda 1,000 miles ago. 

I'm a bit miffed, and slightly concerned. 

 

Thanks in advance. 

[embee 7,288]

My guess would have been chain too tight, but if you say it's right ...............................

 

When you lift the bottom run of the chain does it just touch the rubbing strip on the underside of the swingarm?

[Trumpet 215]

Sounds possibly like shock linkages to me ? Can happen to any Bike, creaking/clicking when shock is compressed over bumps..

Edited May 16, 2017 by Trumpet

[Guest Mac750]

Hi get someone to bounce on the bike to compress the rear suspension whilst you check the shock mounts and  linkages and also the swing arm pivot . As per Trumpets post.

Also see the swinging arm bearing post on this forum and the grim picture posted on the thread.

Check the chain adjustment, again some good info posted on here under chain adjustment and also see a You Tube video on line NCX chain adjustment, as it is not unheard of for a dealer to over tighten the chain and send it back out again.  

Finally if you have a centre stand, with the bike on the stand and the rear wheel off the ground , get someone to hold the bike handle bars and apply the front brake.  You then grab the back wheel top and bottom and try to rock the wheel on its axel checking for any play. Then grab the back of the wheel and try to move the whole wheel and swing arm  left or right , checking for wear in the swing arm pivot area.  

Hope that helps .☺️

[Guest machinman]

Id be checking everything associated with your chain and sprockets replacement, it's too coincidental.

 

[DaveM59 1,603]

Why doesn't it do it below 60mph though? Surely chain or suspension wear would be evident at all speeds if not more so at slower speed.

What changes when you go faster apart from aerodynamics? Possibly wheel bearings or even the cush rubbers.

Does it seem worse when on overrun or coasting or only when on throttle?

[CFB 4,601]

14 hours ago, embee said:

My guess would have been chain too tight, but if you say it's right ...............................

 

When you lift the bottom run of the chain does it just touch the rubbing strip on the underside of the swingarm?

 

Agree.

Because the swing arm pivot is behind the front sprocket and the chain is adjusted with the swingarm at the bottom of its travel.

When the swing arm moves up, the chain tightens, so it is too tight on the sprockets, causing the grating, vibrating feeling.

Did this issue start when the new chain and sprockets was fitted by some chance?

[trisaki 2,029]

Shame you  aren't closer to me in sussex  - I would  have checked the bike over for you  at my wshop  foc  and given my opinion    

[Guest SlinKO PLuSh]

Thanks for the info guys. Going to have a look at the bike later today and get back to you, much appreciated. 

[rjp996 1,091]

On 17/05/2017 at 12:08, CFB said:

 

Agree.

Because the swing arm pivot is behind the front sprocket and the chain is adjusted with the swingarm at the bottom of its travel.

When the swing arm moves up, the chain tightens, so it is too tight on the sprockets, causing the grating, vibrating feeling.

Did this issue start when the new chain and sprockets was fitted by some chance?

 

Just to clarify, the chain is tensioned when the swingarm is not at the bottom of its travel, and this can be an issue when a person adjusts the chain unwittingly with the bike on the center stand / lift, as when the bikes weight is back on the swingarm the chain is then to tight, and tightens more as the shock compresses.

Robin - did you check chain tension with the bike on the side stand so the swingarm is loaded with the bike's weight.

[rjp996 1,091]

prob already been mentioned, but could be bearings - outer bearings on rear wheel sproket side can grind as the chain tightens (wear can be accelerated by someone previously over tighting the chain in the past 10K of the bikes life). I have had inner rear bearings go at 18k so would not be surprised if outer had gone. You can feel them if you take rear wheel off (but remember bearing feel needs to be done under load - eg can feel fine when no load applied).

[CFB 4,601]

7 hours ago, rjp996 said:

 

Just to clarify, the chain is tensioned when the swingarm is not at the bottom of its travel, and this can be an issue when a person adjusts the chain unwittingly with the bike on the center stand / lift, as when the bikes weight is back on the swingarm the chain is then to tight, and tightens more as the shock compresses.

Robin - did you check chain tension with the bike on the side stand so the swingarm is loaded with the bike's weight.

 

Richard, that is correct.

I adjust mine on the centre stand so wrote from that perspective. With the chain adjusted so it is just touching the swingarm when on the centre stand, it is then at the correct measurement when on its wheels.

As we both say, it gets tighter the higher the swing arm travels.

[Guest SlinKO PLuSh]

Thank you for everyone's advice. I'm appreciative of the sentiment Mark that'd you'd look at it, but yes i'm a bit far away!

 

I've checked again and the chain tension is fine on the side stand to my eye, about 3cm  - although yes Murray, the bottom of the chain does just touch the rubber strip on the bottom of the underside of the swingarm, approximately at the point where the fixing for the side stand is. 

Dave - it presents as worse when i'm going downhill actually, and the suspension seems to wallow slightly as I go over road imperfections with the throttle applied, and I get the sensation / noise. 

Update: I spun the rear wheel on the centre stand, and a squeaking noise is evident from the top of the chain, emanating from just where it disappears behind the fairings in the direction of the engine. I thought this was strange because the chain was well lubed; anyhow lubed it again and the noise is still there, albeit more minimally. 

I've got a video of the noise and will try to upload it in the next few days if I can, have limited computer access at the moment. 

 

I appreciate the support from everyone; this is my commuter bike, so any potential issues are a big concern for me. 

[trisaki 2,029]

I wonder if they either didn't change the front sprocket  and its knackered or havent done it up or fitted it properly