Clutch Slippage??

[BrianG]

Last season, I experienced a strange feeling that I'm thinking may be actual slutch slippage. Once the bike was up to operating temperature, I would get the occasional strange feeling upon normal clutch engagement. This feeling was a cross between engagement slipping and rear-end squat.

 

I have never experienced such a sensation before, and I've experienced clutch slippage on any number of motorcycles... from '70's Nortons and Triumphs through Yamaha RZ series 2-strokes, through modern inline-4 sport bikes..... albeit none were shaft-drive bikes. Also, when that sensation was absent the engagement was not "smooth", but rather more like the pulsatile feel of a slightly warped brake rotor.

 

Once engaged, there did not seem to be any further slipping.

 

I am in the throes of splitting the drive-line, but I'm wondering if anyone else is familiar with this sensation? Any ideas of what I'm likely to find once I get in there?

 

Also, I cannot get a clear understanding of which clutch system is in this (2000) model year of V-11 Sport.

 

Is there a clear preference as to which clutch product one should be seeking as the replacement unit?

[Greg Field]

It's what's called a two-plate clutch, meaning two friction plates separated by a steel intermediate plate. Absent a soaking in oil or mechanical malfunction of one sort or another, these clutches last 50,000-150,000 miles, depending on how they're used.

 

I work in a Guzzi shop. We sell a lot of clutches. In my opinion, the latest two series of Guzzi plates are superior to others, in that they last well and offer very smooth engagement. The friction material is riveted to the plates. On very rare occassion, these rivets come lose. I have only seen it happen once in the last 4 years. Bonded plates won't ever have that problem, but in my experience are harsh all the time.

 

The symptoms you describe can be caused by notches worn in the splines of the i.d. of the flywheel or on the o.d. of the trans input hub. Check these carefully.

[Alex-Corsa]

It's what's called a two-plate clutch, meaning two friction plates separated by a steel intermediate plate. Absent a soaking in oil or mechanical malfunction of one sort or another, these clutches last 50,000-150,000 miles, depending on how they're used.

 

Thanks Greg for that info again , I was thinking to precausionary change my clutch (have 52Kmiles on it and dunno if it was changed before) though I don't experience any slipping.

[BrianG]

Is this reasonable at 20,000 km??

[Greg Field]

It would be unusal that there's a problem in the clutch at 20,000 km.

[BrianG]

It would be unusal that there's a problem in the clutch at 20,000 km.

 

My sentiments..........

 

so......... what else could result in the specified symptoms??

[pete roper]

My sentiments..........

 

so......... what else could result in the specified symptoms??

 

Unusual, but not unheard of. The fact that you're getting the pulsing feel at the lever along with the slippage tends to make me think that it is the plates un-rivetting or de-laminating. Another possibility is that one of the two friction plates has ripped it's centre out. Greg would know more accurately than me when the changes occured but there have been at least three revisions of the *late model* Guzzi plates. The very early ones used to rip their centres out with great gusto at low miles, the next generation had thicker steel centres but then the friction material started separating from the part it was riveted too and finally they started both rivetting and bonding the material to the centre! I think that's the order it was done anyway????

 

Although my peanut brain tends to think that all of these upgrades were made before 2000 there is no reason to belive that someone in the factory didn't find a stash of old plates up the back of the store somewhere and sent them to be put into new bikes when they ran out of the newer design!

 

2000 wasn't a particularly good year for Guzzi so it may well be they were scratching around for parts to push bikes out the door

 

Pete

[BrianG]

I guess we'll see what we see when we split the thing....

[Greg Field]

Take it to the steepest hill in your area. Select the first or second gear beyond that which you would normally use for the speed at which you are riding. Watch the tach as you give it full throttle. If the revs rise faster than the speed, that's clutch slippage and a strong clue as to what's happening..

 

Usually—usually—when the plates unrivet the symptoms do not come and go. they show up and stay. Suspect also something in the clutch master/slave system.

[BrianG]

Thanks Greg........ but here at -30 C with 2' of fresh snow on the ground, I think I'll just split the bike and have a look.

[Mal]

Hi Brian

 

This may not be of much use but I was experiencing some very strange feelings from my clutch (ooh err) a year ago, it felt like it wasn't engaging properly and made some odd noises. It vanished as soon I bled the clutch, probably not the problem but worth a try.

 

A good thing is that Guzzi clutches are simple robust units and relatively easy to replace/repair.

 

Good luck

 

Mal

[BrianG]

Well, I decided to open the inspection cover.............

 

 

This is as far as I got today. Boy there are a few "while you are at it" issues to attend to!!

 

Maybe I'll split the transmission cases and seal them up, too!

[BrianG]

Well, there's good news and there's bad news..............

 

The good news is that I can't identify an "issue". It looks good.... no notches on the splines....... the fiber plates look good and so do the friction surfaces. Nice and dry..... no oil from any source. No loose bits......

 

I'm not sure what the part numbers on the friction plates means...... if it's a factory assembly notation or if it indicates a "field repair".

 

I did notice one thing about the clutch-pack assembly, though.... The two "fiber" plates were assembled with the inner spline "flange" facing away from the middle "steel" friction plate. I thought that each flange was to face the transmission side (rear) of the assembly??

 

Anyway...... here are some pics.... comments are appreciated.

 

[Guest ratchethack]

I did notice one thing about the clutch-pack assembly, though.... The two "fiber" plates were assembled with the inner spline "flange" facing away from the middle "steel" friction plate. I thought that each flange was to face the transmission side (rear) of the assembly??

Brian, your comments also have me wondering if the friction plates may have been assembled with one facing the wrong direction. I don't know the proper way they should be (can't remember since I had mine out), but when stacked as they came out, can you tell if the flanges would have interfered with full clamping of the stack as the thickness of the friction pads decreased with normal wear?

 

The friction plates need to "float" freely on their splines without any interference at the hubs. Seems to me you could stack them both ways until it became clear which orientation is correct? There should be ample clearance at both faces of each friction plate hub part when clamped-up.

 

If the spline flanges had been making improper contact, they'd have witness marks, but can't tell from the photos.

 

Just takin' a flyin' swag at it. . .

[pete roper]

OK, a couple of things I can tell you straight up.

 

1.) It's been apart before, those are Surflex friction plates so the chances are the factory plates ripped their centres out or de-rivetted at some time in the past.

 

2.) Both of the friction plates should be installed with the *Raised* bit of the centre spines facing rearwards. If the front one is installed with the raised bit facing forward it will rub on the centre of the pressure plate and prevent the friction material touching the furface or clamping properly. This *may* not occur with new plates but will certainly do so as the friction material wears and this would also fit in with your symptoms. As the splined part started transmitting the clamping force rather than the friction material it would of reached a point where the torque overwhellmed the ability of the surface and force to hold it, hence the slipping feeling.

 

I can't see for sure but are there witness marks on the centre of the pressure plate and the edge of the splined centre that corresponded with it? To me it appears there might be.

 

Anyway, I think you've found the problem

 

When re-assembling make sure you use the correct tool to compress the springs behind the friction plate before installing the plates and ring-gear or you WILL bend the intermediate plate and have to do it all over again!

 

Pete