Front end 'clunk', headstock bearings?
 

Hi all,

I picked up a curvy sv650 today and after some good advice off here have started to service the bike.

TBH it runs really nicely, although not having another carb sv to compare it to within the bike/friend circle it might not be as nice as i think...

It rides well, its my first bike so haven't pushed it plus the tyres are new. However when i go over a pothole/bump i can hear a clunk from the front end, i can also feel this through the steering (slightly). I had a friend pick the font end up so i could shake the forks but i didn't feel any play (might not have been shaking hard enough!).

Any suggestions? does this sound like head stock bearings?

Thanks very much

Rob,

Re: Headstock bearings?
 

That clunk is normal and nothing to worry about if you cant feel any play.They all do it.

Re: Headstock bearings?
 

I get the clunk too but everything's fine.

Re: Headstock bearings?
 

The clunk is normal

Re: Headstock bearings?
 

Lol the perfect answer! had a ride of a friends pointy, it had a slight clunk but it wasn't as bad as mine. Is the curvy more clonky so to speak?

Also its normal to feel it through the grips slightly?

Rob,

Re: Headstock bearings?
 

I thikn it's the fork internals slapping against the insides, it's normal

Re: Front end 'clunk', headstock bearings?
 

Had a really good look at it at the weekend, as you all say its not the headstock bearings, but the actual forks. Its pretty bad tbh and nothing like the clonk of my friends SV.... after a really good search it looks like fork bushes are worn.

A good excuse to rebuild the forks with emulators and thicker oil.


Rob,

Re: Front end 'clunk', headstock bearings?
 

It's your soft standard fork springs bottoming out, you'll need to put stiffer springs and thicker oil in to stop it!!!

Re: Front end 'clunk', headstock bearings?
 

I wish, but this isn't at the bottom of travel, the clonk is there before mid travel, it does it stationary if i rock the bike.

but it will be getting thicker oil and stiffer springs when it gets rebuilt.

Rob,

Re: Front end 'clunk', headstock bearings?
 

Umm, I too have a clonk when going over speedbumps and potholes.
2001 curvy.

Re: Front end 'clunk', headstock bearings?
 

When mine did this I thought it was actually topping out. It definitely wasn't bottoming out.

It seemed to me the clonk was when the wheel dropped off the other end of a speed bump rather than when I initially hit it.

When I put in Hagon progressive springs and oil it improved the handling but still clonked. Stronger linear springs and heavier oil might help. A GSXR front end definitely sorts it. :)

I don't remember being able to recreate the clonk on the sidestand though.

Re: Front end 'clunk', headstock bearings?
 

IMO it's a hydraulic lock. You ask the fork to compress rapidly, the oil gets to the point where it can't travel through the aperture in the damper rod any faster, and so the fork locks up. Change your oil for one with a higher kinetic viscosity than standard and it gets worse, which would explain the difference between your bike and your mates. Just crap forks.

Re: Front end 'clunk', headstock bearings?
 

got this on my 99 curvy, and also had it on my 89 VFR .. have always been told its nothing to worry about

Re: Front end 'clunk', headstock bearings?
 

In my few years experience here and as an owner I've seen nearly everyone post that it does it and no-one post that it posed a problem. a tad annoying perhaps but nothing to worry about.

The threads usually end with

Re: Front end 'clunk', headstock bearings?
 

Most threads do seem to end with that,

But it shouldn't do it, and its really annoying! ahh well, i guess a strip down in summer will show whether i can get rid of it or not.

cheers for the replys!

Re: Front end 'clunk', headstock bearings?
 

Mine does the knock on harsh bumps . No noise just rocking it back and forth , so you need to look deeper .

Re: Front end 'clunk', headstock bearings?
 

Different forks or cartridge emulators are your only options to get rid of it. Or a lighter oil, but that would make the suspension even worse than it already is.

Re: Front end 'clunk', headstock bearings?
 

rob yeah mine clunks but only when you know youve gone a bit to fast over a bump if you know what i mean, where as when i rode yours it seems to do it at the littlest bump in the road, im going gsxr route lol

Re: Front end 'clunk', headstock bearings?
 

Thats assuming the problem is hydraulic lock which im not convinced it is, there are a few threads which claim the knock went away with thicker oil....

Re: Front end 'clunk', headstock bearings?
 

Ill have to have another ride on your ghigo, but i don't remember yours doing it nearly as bad as mine.

Re: Front end 'clunk', headstock bearings?
 

People like to think when they mod their bike it has made it better.

Besides, I doubt many of those people changed just the oil, they probably changed the spring for a heavier one too, so the fork was less likely to compress as fast, and so less likely to create the hydraulic lock. IMO the oil needs to be matched not just to the damper rod, but to the spring as well, and that's the problem with the stock SV, the spring is too soft.

I put too thick an oil in mine because I hadn't checked the cst@40 rating. Funnily enough lots of threads said it was the right oil to use! ;-) The clonk got much worse, to the extent that it would do it going up or down the dropped kerb into the driveway. It wasn't travel as I had a tie wrap on the fork to measure that.

If somebody can give me a plausible explanation I'm all ears, but I'm the only person on this thread offering one. There's one thing for sure, something causes it, and it's not bottoming out and it's not a paranormal phenomenon. ;)

Re: Front end 'clunk', headstock bearings?
 

Thicker oil made mine more prominent.
Your noise don't follow the norm.

Re: Front end 'clunk', headstock bearings?
 

I don't know what makes it do the clonk, I don't think it is cavitation/hydraulic lock as there is no reason for flow to make a knock when it is subjected to pressure, there is no compressibility to cause the knock when this is released.
My best guess is it is the vertical clearance in the damper rod seal allowing the seal to knock up and down.

Pointy has a different rod design, bit less clearance, bit less knock. Perhaps.


If it is worn fork bushings you would feel this when rocking.


We fixed it on your though :-)

Re: Front end 'clunk', headstock bearings?
 

You've changed your mind on that one then. It was you that sent me off reading a paper on 'oil flow through a sharp edged orifice' when WE came up with that explanation for it.

Re: Front end 'clunk', headstock bearings?
 

I can say if wind off the preload the clonk is louder. So it's tightening up somthing in there.

Re: Front end 'clunk', headstock bearings?
 

It is that sort of flow, there is still a limit on how much you can flow through, but I don't think that's the knock.

I believe last time we talked about this it was about the poor comp behaviour of a simple orifice damper as it obeys a ^2 relationship.

Re: Front end 'clunk', headstock bearings?
 

bit of an old post to regurge, but was just surfing the old posts to see about headstock bearings on my curvy, as recently theyve started to clonk over bumps pot holes etc.

Wierd thing is, its never done it in the past 3 years of ownership, but I changed the oil in the forks, for the standard grade, then about 3 weeks later it started clonking :confused:

If they all do it, why did mine never clonk before, and has an oil change brought on the clonk, passed its mot recently and wasnt commented on, no obvious free play, can only detect it riding the bike and its really horrible!

Lee

Re: Front end 'clunk', headstock bearings?
 

Haven't you answered your own question? The standard grade is known to make the noise & that's what you've put in. Different grade oil previously in there?

Re: Front end 'clunk', headstock bearings?
 

32K miles worth of the thinnest brown tea youve ever seen :mrgreen: but the clonk didnt happen straight away, took about 3 weeks of daily use before it became apparent.

Re: Front end 'clunk', headstock bearings?
 

what about vertical play on stanchion bushing? may it be related?

Re: Front end 'clunk', headstock bearings?
 

was chatting to someone today about the clunk, and he suggested the same thing, so will get it looked into, thanks for the replies :cool:

Re: Headstock bearings?
 

They certainly do,had my pointy from brand spankers,knocked from day 1. Because of this i sat on LOADS of new SVs in showrooms afterwards to try them , and every single one of them knocked. You havn't got a problem mate.:)

Re: Front end 'clunk', headstock bearings?
 

You need to fit a Gixer front end.... simples