Modern Vespa

I am still having slight shudder/growling from my clutch bell when the bike is warm and riding slowly in London traffic.

Whilst it is not the end of the world, it is not perfect, which is what I expect.

I have recently removed/cleaned and rubbed the clutch bell, but I suspect I did not rub hard enough! It was still very shiny when re-installed.

Question is, how hard can I rub and does it matter if I do go quite tough with it to get the shine off it? I do read people use scotchbrite pads, but they are even safe on non-stick pans so I have no idea how they make any impact on the smoothness of the surface at all.

Any advice please?

Charles.

I would hit it hard enough to get rid of all the shine. If you are doing this by hand, it would be hard to go far enough to do damage. I use use a product known as Emory Paper here in the US (and maybe in the UK too) for such things. It's like sandpaper but with a cotton backing making it very tough.

These are Harley clutch plates from a 1930's era clutch. But you get the idea of what I'm talking about.

Before, lots of shine and glazing...


After, nice dull surface. You can see a slight cross-hatch pattern from the Emory Paper.

Stop rubbing your clutch bell or you will go blind!!!

You beat me to it.

It's mine and I will rub it as hard as I like!

Blindness is a small amount to pay for a lack of shudder.

Thanks guys, I was hoping I could get quite aggressive with it.

Charles

Thank you for bringing it up. Scotch bright pads comes in many colors. The green kitchen type that you mention is actually the harsher one. And if I ever see you using it on any of my pots and pans I will throw a fit. The same goes for steel wool. I will try the emory paper since I don't any tools to help me scratch my clutch bell. So basically I can sratch the shit out of it by hand, right?

Newbie question: What does that do? Why do you need to deglaze it? Inquiring minds want to know.

If you have a shudder in your scooter when you are taking off from a stop, it can be caused by glazed (shiney) clutch bell friction surface.

-Craig

Don't forget to de-glaze the friction pads with some emery paper after you have roughed up the bell. I would say 150 grit on the bell as you are trying to make it rough not smooth. But the bell won't stay rough for long!
150 will be ok to de-glaze the pads just be a bit gentler.
Not easy but try to rough up the bell across the face and not simply run the paper around the inside.
Sand/bead blasting would be perfect but....

+1.

The first time I ventured into the transmission cover for this, I neglected the pads. On re-do three days later, got the bell and pads. No hurt sea lion or shudder after that.

This thread is not about what I expected. The subject line reads like a bitsa joke.

So, after the advice, this weekend I rubbed the bell down really hard and got a good misty surface to the clutch bell (pads rubbed too).

Guess what - after one ride in some traffic I have the slight noise/rough take off at slow speed.

Seems that the options are

1. Ignore it. Its not the end of the world.
2. Change the clutch bell only
3. Change the clutch and bell etc (if I was sure it would work I would be prepared to do this.

Am I striving for perfection when I am unlikely to get it?

Charles.

Change the clutch bell only. I'll bet it's slightly out of round. On the other hand just ignore it.

I did try to measure it very carefully and I have had my eye on a new bell.

Do I stick with a standard one or get a Pollini or something like that. Is there an advantage of a slight more " performance" version of the bell?

Considering how much I do ride in traffic, it has always got on my nerves though and a new bell is only about £40 which would be a cheap fix if it worked.

Charles.

New bell. Stock. Only.

okay, i'll bite one for the team...can you tell us what belt you're using?
oem or off brand?
any chance you have the belt on, wrong way round?

there are abrasives sponges one can get at the DIY in the wood refinishing aisle. 3M and Norton are ones i use for metal(jewelery) and wood working.

Oh! I've been looking forward to this update forever.

Here is my wise solution before you go ahead and spend your hard earned money on a new bell or a new clutch. Wearing gloves, a mask, and perhaps goggles, get your clutch and spray brake cleaner on it. Don't do just a few sprays. Spray the crap out of it. Do it away from the scooter because that stuff will leave marks on your paint. When you think you are done, spray some more. Brake cleaner dries very fast so work quickly. Use your fingers and thumbs to displace the clutch counterclockwise. If you have a friend with you, ask your friend to spray it for you as you are doing it (or use small c-clamps). Then do some more handcleaning. Use several clean rags. As a final touch if you have access to an air compresor attempt to blow all left over residue in it. Forget the bell. Next turn your attention to the clutch shoes. Those sometimes need to be looked at too. When you are done put it all back together. I promise your shudder will go away. Provided you measured the bell and the diameter is up to your specifications.

One other question. How do your clutch pads look? I know yours is a town bike. On my first ET4, the pads were worn most (normal) at the first contact point where they were thrown out by centriputal force. I coudn't get the judder to stop. It eventually dawned on me when I inspected the pads carefully, that the metal beside/underneath the friction material was shiny and smooth and had been making contact with the bell before the material itself.

My guess that replacing the bell only will work is only a guess. It's cheap enough to give it a go though. Is the leader bell the same as the quasar bell? If it is, I might have a spare. Scootech will certainly have a spare in their pile of second hand stock out the back. Go in and smile nicely at Lawrence or Ian, they are usually very helpful.

Thanks all - I will clean the crap out of the clutch and probably change the bell too. For the £40 or so I do not really want to open it up twice.

The bell glazes really quickly/easily so I suspect it could be out of true and that gets worse when it is hot (perhaps there is a slight warping of it at heat).

The belt is new, OEM and the right way around. This has ALWAYS happened on this bike and just got a bit worse the last year or so.

If you imagine when riding in proper traffic (and being allowed to filter) you are constantly riding with blips on the throttle at about 2-3 mph and trying to balance the bike with tiny amounts of revs. This sort of problem can be a real hindrance to that slow speed control.

Charles.

Since rubbing the bell REALLY hard with 80 grit sandpaper and re-installing then riding for about 2 journeys in town, it is shuddering again.

Took the bell out tonight and it is shiny as normal (you would never know that it had been rubbed at all). Measuring it seems OK - very hard to tell if it is out. As it only happens when it is warm, the only other suggestion could be that it warps when hot. I guess I could put it in the oven for 10 mins and measure again but may be too small a change to be able to tell.

I have a new bell to install tomorrow and I will give the clutch a good clean then too.

Any other suggestions whilst it is apart (has a new belt etc)?

I know it's been said before but do wear gloves when handling the belt. I would double glove if touched anything else. Handle the belt like it is in a sterile evironment. You don't have any grease left in your tranny, do you? Remember it is directional. Good luck!

Ive been having the same problem and been watching this thread for awhile for a solution.So that been said.STOP rubbing it and buy a new bell. I did and it fixed the shutter and slipping.Its worth the $45.00. 8)

Well, its clean, grease free, dust free and installed.

Whilst there I also changed to the Jettin nylon damper bushings.

Shudder is gone (only a short test) - full ride tomorrow to test it out but I have my fingers crossed that this is finally it.

Front bitubo to fit next week then I am done.

Charles.

I know this is dragging on, but probably worth it to consolidate information.

So, after the clutch bell replacement I had some lovely squeal/shudder free riding. I rode about 1000 miles around Nothern France in a few days and it rode really well.

Now back home and the noise is back with a bit of shudder (not much).

Opened up the transmission to find the bell shiny but everything else nice and clean. So, it is now rubbed up nicely and smooth so far, but I suspect it will be back soon.

Should I change the clutch or just put up with having to rough the bell up every couple of months (takes about 30 mins to do now so not a nightmare)?

I found the best way to get rid of the shudder and noise was to adjust the way I was riding. My own findings are that when I don't "gun it" after a lot of stop and start riding the shudder and noise would kick in. BUT if I adopted a more aggressive style of taking off the noise and shudder were no longer a problem.

Just thought I would share my 2c and experience, but make of it what you want!

Howling clutches save lives

I know if I rode like an 18 year old with no family or future then I would be fine, but with 20 years of experience I know better!

I am sure it is my riding style that results in this - I just thought the bike would be more tollerant of a careful and relaxed rider.

Seems not though!

i find that caning it from a stop as a matter of course is a great help in preventing clutch shudder. mine only does this after many months of riding - at which point it's an indication that things need to be opened up and cleaned out.

riding at slow speeds and on the back brake definitely makes the shudder worse,as does pulling away in a "civilised manner" i had the same problem on both my gtv and lx and found riding style almost the biggest factor,oh and 2 up makes it worse...


my advice...gun it at the lights and when riding in traffic not to much on the stop start and back brake....


i did the whole sanding thing and clean out the housing once every week or two with brakleen...

also once in a while open her up on a stretch of shiny black stuff....

after sorting it the last time and paying attention to the way i was riding ive had no return of the sealion...

that was a good 1000km ago...

but then again they are all bloody different....



good luck!

Yep... gun it and go, and clutch shudder will be a thing of the past.

Get a new bell and polini speed clutch same as stock with revised linings. It will never shudder again full stop

Interested in how or if you finally resolved your clutch issue?

Got the bike stolen and replaced with a new one!

Next best solution is to replace the whole bloody clutch and clutch bell. This is a very common problem which, if the standard methods fail to resolve, then a new clutch is the next step.

You can bugger around with springs etc, but it takes a lot of time to do something that may or may not work.

If the clutch is at a reasonable number of miles and if you ride a lot (as I do) in London stop start traffic, then the clutch will wear much more quickly than for countryside dwellers.

Very Interesting thread charles,
I am actually in the process of installing a new polini speed clutch bell to match the polini speed clutch I installed two years ago. A bit of extravagance at 100 Euro but I will post my findings. I was surprised today to find the inside of the cluch bell (old) that I removed was all shiny and the clutch pads were very grubby. I have roughed up the pads with some sand paper and will now see how the new clutch bell works out.

keep us posted on how you get on

I have the squeaky sealion issue too, sometimes at idle if the fuoco's idle goes up a bit.

Is there any other comments apart from rough up the clutch bell and clutch pads with sandpaper and look for abnormal wear.

I have access to a lathe so was wondering if it would be worth taking a tiny bit off the clutch surface with that. And I mean a tiny bit..

Thx

If I may chip in on this. I'm ex-tech and have sorted this issue on many cvt centrifugal dry clutch bikes. Yes, there is a solution to this clutch squeal and judder! I appreciate many of you already may know this but for those that don't this could be invaluable. I'm seeing above in this thread only part of the issue being dealt with so that's the reason for this post. The solution is easier than you may think. After extensive testing on mainly Burgman 400's and the GTS250 and 300's (I've been servicing one for a colleague), I can categorically state the main cause of judder at move off is clutch dust and clutch pad glazing. Rider technique is also a factor in how often this issue arises. This judder is not a fault, but is something that can be avoided with proper maintenance. The belt is not an issue in causing this clutch judder. But here's the thing. Although some folk know what to do to fix the issue, they don't do it right! Read on please.

So, the glazing of the clutch pads is caused, as many of you will already know, by the resin in the clutch pads heating up during move off. The pads get hot and the resin in the clutch pad fibres rises to the surface. This hardens the surface of the pads that contact the bell. During subsequent move off's the pads continue to heat up and some of the resin transfers to the clutch bell. This also mixes with small quantities of clutch dust and the whole clutch thing becomes juddery with often a small squeal at move off. It can be worse when cold or better when cold. It depends how much dust is present in the bell. This is a fairly universal issue with dry cvt centrifugal clutches. It has affected my Burgman, Honda Silverwings, Maxsym 400 and 600's and any bike with this sort of dry clutch transmission. When fixing the issue it is critical to do the right thing. Wrong or poor maintenance is the cause of clutch judder returning very quickly. If done right you will not have reoccurrence of the judder for many thousands of miles.

As the guys are saying, clean out the clutch bell and roughen the surface slightly. I use 100 grit for this and you don't have to go mad at it. Break up the glaze in the bell and spray brake cleaner in it. And as you rub the bell with emery paper, use an even rubbing technique and avoid rubbing in just one place for any length of time. Next, leave to one side. Then, using a small flat wooden block you must CAREFULLY sand the clutch pads. This is the bit folks often get wrong. First make sure you use at least 100 grit on the pad, I use 80 grit. You need to expose the nice clean fibres on the pads and remove all resin. But you don't have to take much material off to do that. Use nice even strokes on the pad and go all the same way as you do it. Use a face mask to stop you breathing in the dust. You should always use a wooden block with the emery paper wrapped around it. DO NOT USE YOUR FINGERS WITH THE EMERY PAPER ALONE. Doing so exerts slightly uneven pressure, however small, on the clutch pads and causes them to become uneven very slightly. It's difficult to see this too so you won't realise it. This means uneven clutch contact patches forming and it will cause the judder to come back very quickly within days or just a few hundred miles. You also get clutch dust building up in the uneven 'dips' in the pads making everything worse. So the secret is to keep the clutch pad surfaces absolutely flat in every plain. Also bevel the leading edge of each clutch shoe pad to allow smooth engagement. There is no need to spray brake cleaner on the clutch pads. If you notice that after sanding the clutch pads there are uneven places showing (you may have to look hard) then sand just a little more. I'd take roughly the same amount off each shoe to keep things even. The pads last a long time so don't worry about the sanding shortening there life span. In total it's not much you should have to remove.

I've proven over and over that this technique works completely. I used to service many many cvt bikes and all complained of this sort of issue. In every case it was because owners did not carry out the maintenance of the clutch correctly. My technique has worked for all of them with no repeat of the judder for thousands of miles. Even those guys that run in town most of the time with lots of stop start. But this leads me to the next point (yeah, sorry it's a long post!).

The correct moving off technique is crucial to maintaining a smooth clutch too. Don't move off slowly with a static low throttle setting. This encourages the clutch to slip more than it needs to heating it up and causing more dust and glazing. IMHO, the best method (and proven) is to wind on the throttle a little more that you need to and let the bike drive off the line in a sprightly manner, adjusting the throttle to get the speed you need after the clutch has locked up. It works! All the guys who's bikes I serviced and who had this clutch issue have adopted this type of move off. No one has ever had to have their clutch deglazed and cleaned out at anything more than the 15k service intervals on the Burgmans an 9k on the GTS. In fact, the GTS guy is coming in later this year for his 9k service. I'll be sorting his clutch maintenance so will do some photos and show you how I do it for those that are interested. But it won't be until summer. I appreciate some of you know all this stuff, but it's worth posting about this sort of stuff. People suffer in silence on this issue I've found and it doesn't need to be. It's curable. Good luck!

Great post!

I must admit that I've been one of the ones suffering in silence for quite a while!

I'll be opening up the tranny tomorrow to check the valves so will do the work required if I have time and report back..

Thx

Well done, great post. Stick around, we like you...

Will favourite this for future reference. Had judder on my previous GTS 125, and cured it with the simple techniques mentioned (not your enhanced technique), but can't remember having it on the 300 these last few years. But if I do, I know which post to go to, this one. Thanks

Spot on , thanks for typing all that. been my exact experience as well.

I've added this to the Wiki article:
FAQ: Shudder, graunching noise on take-off? Sealion?

Thanks!