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slob · 31-03-2020, 08:00 AM

So, a step by step procedure that can produce a quiet clutch in minutes is as follows. I assume that all home Ducati mechanics are able to gain access to the clutch and remove and replace the plate-pack correctly. For this job, there is no need to remove either the clutch centre or the basket, both of which require special tools.

Before you start, you will need to find one or two old friction plates, preferably of the OEM ST2/ST4 steel type, as they are stiffer than the alloy friction plates of the OEM ST4s.

1: Remove the pressure plate and springs, and take all the loose plates out, keeping them in the order of removal. Inspect the edges of the tabs on the friction plates, and the sides of the basket slots. There, you will likely see the wear caused by the tabs slamming to-and-fro in the slots. If the slots have deep notches in them, a new basket may be needed in the near future, or smooth engagement could be compromised by the tabs sticking in the grooves. There is nothing to be gained by filing the burrs off the tab sides, as this just reduces the contact surface-area again.

2: Drop one of the old junk friction plates into the basket first, pushing it right down into the slots. As the tabs on the plate reach the radiussed ends of the slots, they will lock into the curve while pressure is applied, and cannot rattle to-and-fro. This is the first significant aspect of the mod.

3: Then add the second old tabbed friction plate.

4: Now slide the first plain steel plate onto the clutch centre and push it as far in as it will go. For the quietening mod to work, that steel plate has to contact the face of the previous friction plate before it hits the bottoms of the splines/slots on the centre. The amount by which the friction face protrudes needs only to be around 0.020”/0.5mm, and more will not be better. This dimension will likely be different with the various options of OEM and aftermarket components you might be using, and is also influenced by any wear on the front face of the clutch centre. Checking the amount of overhang will require a short straight-edge that can be laid across the friction faces adjacent to the roots of the slots in the centre. It may be that sufficient overhang is provided by only one extra friction plate, though this dimension will likely diminish as the tabs bed into the basket slots with use.

5: Replace all the other plates as they came out, including the cone-shaped spring-plate, whose exact position and orientation does not seem to be critical. (Note that the wave-profiled spring plate in the Barnett plate-pack gives more resilience, and may be a factor in abolishing the famous ‘groan’ on take-up. Refacing your stock plates can apparently work too).

6: Disregarding the extra one or two plates in the bottom of the basket, your effective plate-pack thickness should only have increased by that 0.020”/0.5mm mentioned in 4 above. This should mean there will be no issues with plates coming out of the basket slots or off the centre when the clutch is disengaged, especially if your plates have seen some use. However, you should check this before running the bike. The specified max thickness of the pack is 38.5mm, but a mm or so less is permissible.

If you have to juggle with plates, remember that different brands vary in thickness and number, and I see no problem with mixing-and-matching plates to get the right total thickness. If you find it difficult to get down to the 0.020”/0.5mm overhang, you could always reduce the thickness of the friction material on the additional plates, but do it evenly on a flat surface to keep the outer surface square to the rest of the components. Finally, make sure that the very last plate you put in is a plain steel one for the pressure plate to contact.

31-03-2020, 08:00 AM	#3
slob . Join Date: Jul 2003 Location: East London Bike: Multiple Monsters Posts: 9,710	So, a step by step procedure that can produce a quiet clutch in minutes is as follows. I assume that all home Ducati mechanics are able to gain access to the clutch and remove and replace the plate-pack correctly. For this job, there is no need to remove either the clutch centre or the basket, both of which require special tools. Before you start, you will need to find one or two old friction plates, preferably of the OEM ST2/ST4 steel type, as they are stiffer than the alloy friction plates of the OEM ST4s. 1: Remove the pressure plate and springs, and take all the loose plates out, keeping them in the order of removal. Inspect the edges of the tabs on the friction plates, and the sides of the basket slots. There, you will likely see the wear caused by the tabs slamming to-and-fro in the slots. If the slots have deep notches in them, a new basket may be needed in the near future, or smooth engagement could be compromised by the tabs sticking in the grooves. There is nothing to be gained by filing the burrs off the tab sides, as this just reduces the contact surface-area again. 2: Drop one of the old junk friction plates into the basket first, pushing it right down into the slots. As the tabs on the plate reach the radiussed ends of the slots, they will lock into the curve while pressure is applied, and cannot rattle to-and-fro. This is the first significant aspect of the mod. 3: Then add the second old tabbed friction plate. 4: Now slide the first plain steel plate onto the clutch centre and push it as far in as it will go. For the quietening mod to work, that steel plate has to contact the face of the previous friction plate before it hits the bottoms of the splines/slots on the centre. The amount by which the friction face protrudes needs only to be around 0.020”/0.5mm, and more will not be better. This dimension will likely be different with the various options of OEM and aftermarket components you might be using, and is also influenced by any wear on the front face of the clutch centre. Checking the amount of overhang will require a short straight-edge that can be laid across the friction faces adjacent to the roots of the slots in the centre. It may be that sufficient overhang is provided by only one extra friction plate, though this dimension will likely diminish as the tabs bed into the basket slots with use. 5: Replace all the other plates as they came out, including the cone-shaped spring-plate, whose exact position and orientation does not seem to be critical. (Note that the wave-profiled spring plate in the Barnett plate-pack gives more resilience, and may be a factor in abolishing the famous ‘groan’ on take-up. Refacing your stock plates can apparently work too). 6: Disregarding the extra one or two plates in the bottom of the basket, your effective plate-pack thickness should only have increased by that 0.020”/0.5mm mentioned in 4 above. This should mean there will be no issues with plates coming out of the basket slots or off the centre when the clutch is disengaged, especially if your plates have seen some use. However, you should check this before running the bike. The specified max thickness of the pack is 38.5mm, but a mm or so less is permissible. If you have to juggle with plates, remember that different brands vary in thickness and number, and I see no problem with mixing-and-matching plates to get the right total thickness. If you find it difficult to get down to the 0.020”/0.5mm overhang, you could always reduce the thickness of the friction material on the additional plates, but do it evenly on a flat surface to keep the outer surface square to the rest of the components. Finally, make sure that the very last plate you put in is a plain steel one for the pressure plate to contact.