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Old Wizard
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Discussion Starter #1 (Edited)
Ducati Clutch Basics

The Ducati dry clutch is famous for it’s unique noise that makes it desireable to some but an annoyance to others. The reason that they’re noisy is that each time you shift, the edges of the friction plates hammer the fingers of the clutch basket, causing each to deform, and making the gap between them to get larger, causing higher impact forces (the next time), and so on, causing a louder rattling noise each time the clutch is disengaged. So, they get louder and louder until the plates and basket are replaced.

The noise doesn’t necessarily mean that your clutch is worn out. A clutch is considered worn out when the thickness of the friction material on one or more friction plates exceeds the minimum allowable. It’s recommended that you replace a 3mm (new) friction plate when it reaches it’s service limit of 2.8mm, and replace a 2.5mm friction plate when it reaches 2.3mm.

When the plates wear, the plate stack height is reduced so when the stack height wears 0.5mm, you can replace one flat steel plate with a one 0.5mm thicker to recover the correct stack height. At 1.0mm wear repeat for a second flat plate. At 1.4mm wear you’ll want to replace the friction plates. This is the time to replace the basket if you want to quiet your clutch.

Ducati Clutches need to be stacked to 38mm plus (+) or minus (-) 2mm.* The reason that maintaining the overall stack height is important is that the force pushing the plates together comes from the preload of the clutch springs. The higher the stack height, the higher the preload. Also for a given stack height, the more springs the higher the force pushing the plates together. Not enough spring preload, not enough springs, or not enough friction material and your clutch will slip.

The standard test for a slipping clutch is to check while accelerating in top gear.


Quiet Clutch Mod

It’s been sugested that adding a plate at the bottom of the stack will reduce clutch noise. This plate is not an addition to the existing stack, the stack height has to be maintained. This is a rearrangement of plates in the stack.

The idea here is to move the friction plates to a new location in the stack so that they no longer are alligned with the notches in the basket (notches that they caused previously.) This in turn reduces the tab-to basket clearances for the friction plates so you get less noise.



The arrangement of plates in the stack, the number of plates, and the thickness of plates vary from model to model, but the one feature that all arrangents have in common is stack height. Here’s some examples:


748, 916, 996 (From the Haynes Manual)
7 friction plates
1 convex plate


2.0mm flat plate
2.0mm*flat plate
3.0mm friction plate
1.5mm convex plate (convex side facing outwards)
3.0mm friction plate
2.0mm*flat plate
3.0mm friction plate
2.0mm flat plate
3.0mm friction plate
2.0mm*flat plate
3.0mm friction plate
2.0mm flat plate
3.0mm friction plate
2.0mm flat plate
3.0mm friction plate
2.0mm flat plate
pressure plate (line up marks)
38.5mm Total


916SP, 916SPS, 996S, 996SPS
8 (thinner) friction plates
2 convex plates


2.0mm flat plate
1.5mm convex plate (convex side facing outwards)
2.5mm friction plate
1.5mm*flat plate
2.5mm friction plate
2.0mm flat plate
2.5mm friction plate
2.0mm*flat plate
2.5mm friction plate
2.0mm flat plate
2.5mm friction plate
2.0mm*flat plate
2.5mm friction plate
2.0mm flat plate
2.5mm friction plate
1.5mm flat plate
2.5mm friction plate
1.5mm convex plate (convex side facing inwards)
pressure plate (line up marks)
38mm Total


998 (From the Ducati Service Manual)
6 friction plates
1 convex plate


2.0mm flat plate
1.5mm convex plate (convex side facing outwards)
2.5mm*flat plate
1.5mm flat plate
3.0mm friction plate
2.0mm*flat plate
3.0mm friction plate
2.0mm*flat plate
3.0mm friction plate
2.0mm flat plate
3.0mm friction plate
2.0mm*flat plate
3.0mm friction plate
2.0mm flat plate
3.0mm friction plate
1.5mm flat plate
2.5mm*flat plate
1.5mm convex plate (convex side facing outwards)
pressure plate (line up marks)
38mm Total

Of course shifting the plates around to reduce plate-to-basket clearances is only a temporary fix until the plates hammer-out new and bigger clearances.

More Lasting Solutions

There has been some innovation to try to address the durability issue associated with the plates impacting and notching the basket.

For example, STM and Sigma (UK) has tried to overcome this problem by increasing the number of tabs on each plate (and the number of basket fingers) from the stock 12 to 48 tabs. The intended result is to distribute the impact loads over a larger tab-basket contact area (lower psi) to reduce notching to the clutch basket fingers and mushrooming of the plate tabs. Only STM and Sigma offer a 48-tab clutch pack, however.

Nichols Manufacturing designed their CNC-machined aluminum basket with wider basket fingers that results in larger finger contact area and consequently lower impact stresses, particularly when combined with their Barnett aluminum clutch pack where extra care has been taken to initially minimize gaps. Basket: $299, clutch plates: $139.

Another option is a Barnett aluminum basket with stainless steel inserts to protect the basket fingers. About $225.

Keep in mind that when you mix steel and aluminum, the softer metal deforms preferentially and clearance gaps suffer, more than for steel-to-steel. So if you have a steel basket, stick with steel plates.
 

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Good write up shazaam. The quiet clutch mod that I have used uses 1 or 2 friction plates in the bottom of the stack so that they sits against the bottom of the slots in the basket rather than the steel plates sitting against the bottom of the splines in the hub.

This prevents plates from rattling by having the pack loaded against the outer basket rather than the inner hub when disengaged preventing the rattle.

This is easier to do on the older sqaure bottomed slot steel baskets like the 90's 900 SS rather than the aluminium radiused bottomed baskets.

Less rattling means longer life for the tabs, meaning you could wearthe plate friction material out before the basket gets heavy slots.

There could theoreticaly be additional load placed on the hub bearing but haven't heard of anyone having one fail.

This is different from the quiet mod you have mentioned.
 

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Good write up shazaam. The quiet clutch mod that I have used uses 1 or 2 friction plates in the bottom of the stack so that they sits against the bottom of the slots in the basket rather than the steel plates sitting against the bottom of the splines in the hub.

This prevents plates from rattling by having the pack loaded against the outer basket rather than the inner hub when disengaged preventing the rattle.

This is easier to do on the older sqaure bottomed slot steel baskets like the 90's 900 SS rather than the aluminium radiused bottomed baskets.

Less rattling means longer life for the tabs, meaning you could wearthe plate friction material out before the basket gets heavy slots.

There could theoreticaly be additional load placed on the hub bearing but haven't heard of anyone having one fail.

This is different from the quiet mod you have mentioned.
+1, this is not the same quiet mod that was discussed in the other thread
 

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I agree with Corse. The original quiet clutch mod reducers the space for the plates to rattle by adding two steel plates at the back rather than as suggested in the original post that it merely moves the plates so that they vibrate or rub on a different part of the basket. I did the quiet clutch mod and am well impressed with it as it does not take away completely the dry clutch rattle that we all love so much when disengaged or in neutral, it rather just reducers the clatter a tad..
 

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why is it that ducati designed the clutch this way however?
Being dry, the clutch doesn't loose torque spinning in a fluid. I read once, and thought it well said "Ducati designed the bike, then thought about the rider. Other bikes are designed for the rider, then thought about the bike"

The reason that they’re noisy is that each time you shift, the edges of the friction plates hammer the fingers of the clutch basket, causing each to deform, and making the gap between them to get larger, causing higher impact forces (the next time), and so on, causing a louder rattling noise each time the clutch is disengaged. So, they get louder and louder until the plates and basket are replaced.
Shazaam, great write up!

In neutral with the clutch engaged the plates are banging away against the basket in the torque ripple of the 2 cylinders. Could this also be a contributer to the notches in the basket?
 

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I received a clutch pack but it didn't contain a convex plate. Do I need to find a replacement?

ps. It's for a '97 748bip

pps. The old plates were all discarded.

Thanks in advance and thanks for the great write up.
 

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When the plates wear, the plate stack height is reduced so when the stack height wears 0.5mm, you can replace one flat steel plate with a one 0.5mm thicker to recover the correct stack height. At 1.0mm wear repeat for a second flat plate. At 1.4mm wear you’ll want to replace the friction plates. This is the time to replace the basket if you want to quiet your clutch.
Will this work for a wet clutch as well? Also, instead of replacing a .5 with a 1.0, could you just add an extra .5mm plate? My second clutch is starting to slip, but I still have my original clutch pack to steal plates from.
 

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Chilehead
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Will this work for a wet clutch as well? Also, instead of replacing a .5 with a 1.0, could you just add an extra .5mm plate? My second clutch is starting to slip, but I still have my original clutch pack to steal plates from.
Plates are either 1.5mm or 2.0mm, not 0.5mm and 1.0mm

Tom
 

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Experience with my 1098 dry clutch (the first I've owned with alloy basket and friction plates) suggests that 30,000 kms is about all that can be coaxed out of that plate/basket engagement point, with mainly road (and occasional track) use. After that all the plate-shuffling in the world won't make it take up nicely.
At 30,000 I fitted a set of new plates and an MPL anodised basket. The plates were a neat fit in the MPL slots, and very quiet for a while. The basket being anodised should also delay the inevitable. Now, at 9,000 kms from the clutch replacement it is still less rattly than my friend's 6,000 km bike, and working well.
 

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I've been reading this and other clutch topics for a month or 2, preparing to replace my fried clutch plates. Bike has just over 30000km on it and as far as I know, the clutch was the original. My mechanic recently said the plates were glazed and did a temporary fix (?added extra plate/s - I didn't know to ask him at the time).

On the topic of quieter clutch mods... http://www.ducati.ms/forums/showthread.php?t=70205 ...I found it curious that my worn out clutch seemed to sound the same as this mod describes ie. "gloriously quiet clutch when in neutral with the clutch out. However, the beloved sound with the clutch pulled in". On pulling it apart I found that there was an extra friction plate under the first two steel plates, as the mod describes. This may have been added by my mechanic - I'll ask him next time. It was an extra thick friction plate with friction material (though totally worn) on one side only - see attached pic (thick plate on the left, alongside new Barnett friction plate for comparison)

I went with a Barnett pack as a replacement but kept the thick used friction plate back on the bottom to retain the quiet clutch mod benefits, followed by 2 thick steel plates, then alternating frictions & steels. Stack height ended up about 38mm (see attached pic). To get this I left one friction plate and the curved/dished plate out. On subsequent reading I see the curved plate is meant to give a more progressive clutch action, so I am thinking of at adding it in and adjusting a bit more. SO... being the first time I've done this, I have a couple of questions...

1) the curved plate from the Barnett pack looks more warped and twisted to me than just purely 'curved' or convex (see attached pic) - is this normal? I thought plates needed replacing if they were warped, but this one is straight out of the packet.

2) Do you always need to alternate friction and drive plates? If so, how is it ok for the first two steel drive plates to be together? Can you have 2 steel drive plates together elsewhere in the stack to adjust the height?

The clutch is working fine as it is but I wondered about the "more progressive feel" thing with the curved plate so just want to check what is ok to do on that front. I love the quiet clutch mod for all the reasons listed by others, so will be sticking with that part :D

Thanks in advance for any input ;)
 

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The dry clutch rattle from my Duc is just like the olden days of dry clutch rattle on a TZ!
The louder the better!!!
Many a clutch handle heavyness is fixed by scquirting some penetrating lube, CRC- INOX, into the bottom and top of the clutch handle pivot point!
And lubing the cable propperly:)!
 

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So to be clear, a small amount of rattle is natural when you are in gear, and driving? I put an open cover on my 748 today, and noticed that it rattles underload. Its light, but certainly noticable. Clutch is not slipping, and engagement is normal.

If you put an open cover on a new dry clutched Duc, would it rattle a bit even when you were accelerating?
 

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I am going to try this mod out later today and I have to admit that I still dont fully understand what I need to do to my clutch pack.
I have a 1999 996 biposto.
If I read correctly, this mod does not require any extra plates or new plates and is therefore free.
Can someone list the stock 996 plate order and then the 996 plate order that would be used for this mod or seen after this mod is complete?
 

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96 ss900 I used Barnett aluminum clutch, installed I old friction plate at bottom of stack, did not include this in stack ht. measurement as far as I can remember. I had an alloy basket to install, but found PO had already installed one , it was in decent shape even though it had been used with steel plates, so I saved the new one. It didn't have adequate clearance in the slots for free function, anyway. Clutch works flawlessly, noise much reduced but still there when clutch lever is pulled in at a light.
 

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Right...but you used an old plate. This isn't the same thing. This is a rearrangement of the existing plates. Anybody?
I won't tear into it at the moment be side I just feel too lost without the plate movement clarified so I know which plates move where.
 

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Fitted a brand new all alloy clutch to the Monster today; MPL basket, SSR hub and Newfren plates, quiet as a mouse with no audible difference if lever pulled in or not - quietest I've ever heard.

I give it 1000 miles before it rattles like a skeleton wanking on a tin roof into a tin can... :rolleyes:
 
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