[Strega]

You failed to mention how many miles are on the clutch.

The standard test for detecting worn-out clutch plate friction material is to watch for slippage when accelerating in top gear. Some people are just harder on clutches than others, so service mileage will vary over a wide range.

You can often stop slippage by maintaining the force pushing the plates together. The idea here is to maintain the 38 mm new stack height as the friction material wears off and reduces the thickness of each plate. The higher the stack height, the more the springs are shortened/compressed, and the greater the force pushing the plates together. The clutch slips when there's not enough force supplied by the springs or the friction material is worn completely off.

The service limit on 3 mm friction plates is 2.8 mm. For 2.5 mm plates the service limit is 2.3 mm.

The plain metal plates come in stock 2.5 mm or 3 mm thicknesses. When the overall plate stack height wears 0.5 mm, replace one 2.5 mm flat plate with a 3 mm one. At 1 mm stack height wear, repeat for a second flat plate. At 1.4 mm - 1.6 mm wear, replace all the friction plates. Allowable friction plate wear is 0.2 mm (each).

Ducati considers both the plates and clutch basket to be wear items. By the time you need to replace the worn-out clutch plates the basket has been notched from the impact loads of the plates. Ducati specifies the allowable gap between the plates and basket as a quite small 0.6 mm, effectively saying to replace the basket and plates together.

Also check the pressure plate throwout bearing and pushrod for smooth rotation.

 

[Old rider]

About a dozen rides ago, my not-aggressively-ridden SS/SP began to make a little “chirp” sound whenever I'd sport shift it up a gear. Nothing drastic or alarming, just a little noise when I'd slightly roll off the throttle to let the shift lever move up on its own.

Last night and this afternoon, however, I noticed that if I attempted to accelerate in 4th, 5th, or 6th, she'd just rev.

What should I do next?

Should I just assume I need to get a new stack of plates and springs?

Or are there maintenance things I should be considering?

Thanks in advance. You guys have always helped me get her back on the road quickly. There are no Ducati dealers here in town —*you've all been my guidance counselors; that and my Haynes manuals.

My stack height is in the low 30s and I have applied white lithium grease to my friction plates, my tweaked 999 delivers 128.5 bhp at the rear wheel through what is essentially the same clutch as you have, yet I get no clutch-slip.
Do you have the required minimum play at your clutch lever - iirc, 1-2 mm?? If you have no free-play at the clutch-lever, the full pressure of the clutch springs is not pressing your clutch plates together.

 

[casor]

Before you do @Strega's full monte, make sure you check the transfer/actuating rod that runs from under the slave to the clutch, from one side of the engine to the other. These thing freeze up with alarming regularity. What happens is that there is enough force to actuate the clutch, but the rod will not retract entirely since it is hung up in its bore. You don't need much interference to have a problem.

Remove the slave, pull the rod and clean the bore with WD-40 and a gun cleaning brush on a rod and then wipe it all out with the rod and a bore wipe cloth. Clean up the rod, install new o-rings (forget if one or two) and apply a light smear of synthetic grease upon reassembly.

Your goal should be to "zero time" this system. Do the maint stuff first - bleed, clean, check, no leaks etc. If still not working, then you now have to zero time with a fix per the above

 

[BelgianDuc900SS]

I had the exact same problem a few weeks ago. The clutch sometimes started making strange 'chirping' sounds and when revving up to higher rpm's it sometimes completely failed.

My advice: make sure to check the friction plates before adding ticker steel plates.

If you have been riding with a slipping clutch it is possible that your friction plates are glazed and when that happens it's useless to add ticker steel plates. These glazed plates were the problem with my clutch. My stack height was perfectly within specs. But I had two broken clutch plate springs and a slave cilinder with lots of rubbish on the inside. Probably the reason why my clutch had been slipping for quite some time.

Glazing is the proces when the friction plates get hot (like when they are slipping, maybe even without the driver noticing it) and the binding material of the plates starts to 'melt' or 'liquidify'. This stuff then comes to the surface of the friction material and smoothens the surface, possibly even to the point where your friction plates start shining like if they were polished.

I don't know any solution for glazed plates besides replacing them.

Another thing that surprised me was how much dirt came off 'clean looking' steel plates when cleaning them with brake cleaner.

 

[ducvet]

Great info sofar I will try and not derail that fact.

Start by checking for lack of freeplay at the master cylinder, make sure there is free travel if you have none you will slip the clutch (any new levers?).

Disassemble the the clutch pack and inspect everything, do the same with the clutch pushrod .
A quick check on the friction plates is that most frictions will have grooves cut between the frictions on the plate, if the grooves are gone (much like brake pad wear indicators) then you likely need new plates. Note there are a few brands (Dp) that do not have wear grooves cut.

If everything looks good then next inspect that the large 32mm clutch nut has not come loose. Inspect the inside of your clutch cover for signs your clutch is now touching the inside of your cover.

In my experience it is very rare to wear out a dry non-slipper clutch, but with any used bike anything is possible. Worn components and people doing burnouts can shorten the life to a fraction of average lifespan. Since we cannot rule out the past we just look for something worn,loose or aout of spec causing the slipping.

I will assume you do not have a slipper clutch in the bike but you have not given us many details on the bike yet. Pictures,miles?

 

[belter]

i've had a couple of clutch slipping incidents in the last few years after a fluid flush and bleed where freeplay was the issue. no adjustment made, just the fluid. wacky.

i saw a pushrod so worn once that when i replaced the pack (900ss owner was a known clutch killer) and pumped the lever up the piston popped out of the slave. went bang and scared shit out of me.

 

[pneumadeux]

Now that I think of it, yes —*my “chirpring” started not long after I did a bleed and refill of my Yoyodyne slave cylinder.

Within 2 rides, the fluid was back to it's usual dark color, which I've been told is normal for these bikes since the lines are situated in such a way as to “cook” the fluid. I’ll be open to the forum’s point of view on that one...

 

[pneumadeux]

Remarkably helpful, Strega.

I'll start with my feeler gauges and my micrometer and see what that yields.

 

[pneumadeux]

Full disclosure on the age / mileage of the friction plates, etc.

It's a full Barnett set: basket, plates, and springs, with a chromed CycleCat open cover.

Approximately 17K miles, mostly commuting and local interstate miles. Never dropped.

Bike has 47k miles all total. I posted a pic in the Show Us Your Duc forum. I'll see if I can find a link.

 

[Old rider]

So you've already checked for free-play...

 

[pneumadeux]

Here's a link to a picture of Sophie (1995 900SS/SP) at the end of last summer. You can see the described clutch basket here.

https://drive.google.com/open?id=1K8rUQ1UccNzIpJv1dbGa_QK29F4dvT-B

 

[pneumadeux]

Yes, I have roughly 1/2-inch of freeplay in clutch lever travel, measuring from the tip.

 

[ducvet]

Barnett clutches do not last as long as oem clutches so it is possible the friction plates are worn.

Go back to the slave/bleed and make sure that you have freeplay at the lever. Levers are adjustable for freeplay so if the lever is not oem or oem replacement you have to set it when you install. If the lever was adjusted with air in the line and then you remove the line you would have less freeplay and the clutch may slip especially when hot as the engine grows with heat and settings change.

Take a close look at the pushrod at the clutch end of the rod and look for a step that should not be there. when the bearing runs dry or fails you will mill down the rod and the step can cause it to hang up. compare yours to pictures of new pushrods it does not matter the model none would have a step where the bearing is located.

Is there a reason your rear brake reaction rod is installed upside down?

 

[pneumadeux]

Thank you for this, ducvet. I'll check the rod for that step, indicating that I'd need a new bearing...

As to your question about the “reaction rod,” I'm afraid I'm at a loss as to what you mean?

 

[RockAZ]

It took me a bit of looking to figure it out, but the piece on the engine case that the reaction rod connects to is upside down on your bike. Here is a picture of the "elbow" piece he is talking about installed correctly. It seems to me that the Aussie style you have would actually impede the swingarm travel when it goes over a bump?

And here is a close up of yours

 

[pneumadeux]

That's seriously fascinating.

I bought the bike used over 20K miles ago... that piece has never been off since I purchased the bike! Looks like I should be flipping that!

#ThingsThatMakeYouGoHmmm

 

[pneumadeux]

Obiously, I can inspect the pushrod ends by simply pulling the Yoyodyne and the clutch pressure plate. But if I end up replacing baskets et al due to things being out of spec, is it essential that I drain the oil first before extracting the pushrod?

 

[ducvet]

Once the pressure plate is off for you to inspect the clutch you can slide the rod out and inspect the rod as well as the needle bearing in the shaft.

Sounds like you have plenty of freeplay so on to checking the shaft,clutch plates,clutch hub nut.

 

[pneumadeux]

Wow. The stack height is a very worn 24.6mm. And the gap between the plate "tangs" and the space in the basket is far from .6mm: try 2.2mm!

I'm surprised that the slippage only now started manifesting.

The bearing is fine and smooth. The ends of the rod are not capped in any way. I have not pulled the rod, however.

Here's my new question:

The gold Barnett basket does not show any signs of "hammering" on it's splines, at all.

Is there a way for me to measure to see if I just need to get a new plate stack, rather than pick up a new basket, also?