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Front end 'clunk' / knock

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alanp
Rossi
Rossi

Posts : 53
Location : Norfolk, UK

Front end 'clunk' / knock

Post by alanp on Wed 07 Sep 2016, 3:05 pm

Hmmm - my bike has developed a slight 'knock' or 'clunk' at the front which I'm trying track down and cure. I feel it through the bars when riding over rough surfaces, or most particularly when approaching a roundabout that has those annoying thick yellow 'rumble lines' leading up to it.

My first thought was the headrace bearings and whether they'd gone a touch slack. I changed them about 500 miles ago, and already checked and nipped them up after they'd settled in after about 100 miles. If I put the bike on the main stand and pull the front around I can't feel any remaining slop. The turning flops easily and smoothly from side to side so I think the setting is about right.

Any thoughts? Is it worth nipping the headrace again (I don't want to over tighten it)? Are there any other known front end clunks/knocks on these bikes? I can't spot anything obvious...
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Jameshambleton
Moderator
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Posts : 1722
Location : Bedale, North Yorkshire

Re: Front end 'clunk' / knock

Post by Jameshambleton on Wed 07 Sep 2016, 3:43 pm

Wheel bearings, brake caliper bolts tight, retaining pad for the brakes. Check every bolt on the front end including the fork clamps.
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eternally_troubled
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Posts : 3639
Location : 'ere be fens. (near Cambridge)

Re: Front end 'clunk' / knock

Post by eternally_troubled on Wed 07 Sep 2016, 5:26 pm

@Jameshambleton wrote:Wheel bearings, brake caliper bolts tight, retaining pad for the brakes. Check every bolt on the front end including the fork clamps.

I'll second that.

You can sometimes get a klunk from the brakes or from the suspension. You might be able to test these by pulling on the front brake and bouncing the front of the bike up and down - might be worth having an assistant listen to see if they can identify where the klunk is coming from (assuming you can reproduce it).

muttley1
the 900
the 900

Posts : 742

Re: Front end 'clunk' / knock

Post by muttley1 on Wed 07 Sep 2016, 5:44 pm

I had this on the most recent cb5 I resurrected, a bit worrying and my headraces were ok too. I changed the brand of front pads and put in a new pad pin, fixed.

Btw I had an sv650s and it had a front end clunk too but they all do that sir, its a well known "problem".
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alanp
Rossi
Rossi

Posts : 53
Location : Norfolk, UK

Re: Front end 'clunk' / knock

Post by alanp on Wed 07 Sep 2016, 7:44 pm

Thanks all.

I've just checked all the bolts etc at the front, all ok, and nothing touching or catching that shouldn't. 

The only thing I can find is movement in the caliper and pads, which I'd normally expect (calipers on all my bikes float around a bit) - but given muttley1's comments above I wonder if a quick strip down and proper check is in order? I'll give it a go and report back.
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alanp
Rossi
Rossi

Posts : 53
Location : Norfolk, UK

Re: Front end 'clunk' / knock

Post by alanp on Tue 13 Sep 2016, 8:50 pm

Just reporting back. I'm pretty sure that it is the headrace. I basically spent a few minutes vigorously, errr, 'humping' (!), the front of the bike and sure enough could feel the headrace knocking.

Now I've been through a frustrating routine of tightening it up a bit, which got rid of the clunk but made the bike wander horribly. I then loosened it a gnats whisker, and the wandering has gone but the clunk is back. Grrrr

I'm surprised that it's so sensitive to the small adjustments. It makes me wonder if the bottom race is seated properly - the recess was badly mauled inside the headstock by a previous 'mechanic' when I changed the old ones over.
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eternally_troubled
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Re: Front end 'clunk' / knock

Post by eternally_troubled on Wed 14 Sep 2016, 6:59 pm

@alanp wrote:Just reporting back. I'm pretty sure that it is the headrace. I basically spent a few minutes vigorously, errr, 'humping' (!), the front of the bike and sure enough could feel the headrace knocking.

Now I've been through a frustrating routine of tightening it up a bit, which got rid of the clunk but made the bike wander horribly. I then loosened it a gnats whisker, and the wandering has gone but the clunk is back. Grrrr

I'm surprised that it's so sensitive to the small adjustments. It makes me wonder if the bottom race is seated properly - the recess was badly mauled inside the headstock by a previous 'mechanic' when I changed the old ones over.

From my experience with other bikes it can be a very sensitive adjustment, I assume the CB500 is not different.
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hh_12345
Silver Bullet
Silver Bullet

Posts : 101

Re: Front end 'clunk' / knock

Post by hh_12345 on Wed 14 Sep 2016, 7:45 pm

My bike also feels the same, it is the caliper, but mainly the head bearings.

I tightened them a bit and the knock is less noticeable,  but the handling is also negatively affected.

There are really small marks in the top race that probably cause it.Sad

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