Ducati Bevel Drive Clutch Replacement and Adjustment

Technical Guide

Ducati bevel drive motorcycles have long been renowned for having ‘heavy’ clutches, clutches that tend to slip, and clutches that can feel ‘grabby’.

Before we go much further, it’s worth noting that all bevel drive V-twin Ducati motorcycles with wet clutches use the same clutch. Round case or square case engines, it makes no difference. Later bevel drive engines that use a dry clutch have a different configuration, including hydraulic operation, but many of the issues we mention here can still be encountered on these dry clutch set ups.

There are many fixes that enthusiasts have employed over the years at home in their quest to make these clutches easier to live with, like heavier clutch springs and longer clutch arms for example but these are only bandaids and don’t go to the heart of the problems.

There’s a number of wear points that can cause the clutch to operate poorly.

Clutch Basket:

This is the outer part of the clutch that is bolted to the primary gear. It holds the tangs on the outer section of the friction plates in place and this is the major wear point on the basket. Over time these tangs wear into the recesses on the clutch basket, creating highs and lows, or ‘notches’ which can cause the friction plate tabs to get caught on these notches.

Clutch Hub:

The clutch hub sits inside the clutch basket and slides over the spline of the gearbox mainshaft. The steel plates have teeth on the inside circumference and these slide over ‘grooves’ in the outer circumference of the clutch hub. These outer grooves can also wear from the teeth on the steel clutch plates. 

(The whole system works with the pressure plate pushing the fibre and steel plates together, and the clutch basket is then able to drive the clutch hub, via the clutch plates, which in turn rotates the gearbox and front sprocket. Usually you will find wear on both the basket and hub from the clutch plates. The worse that wear is, the worse your clutch will feel.)

Clutch Plates:

The friction plates’ main wear point is the fibre itself. This is bonded to the plate itself and as this friction material wears it becomes thinner, so eventually the pressure plate cannot exert enough force on the plates to get them to ‘drive’ together.

Steel doesn’t wear like fibre but it can deform or ‘warp’, usually due to excessive heat.

Most manufacturers will list a minimum thickness for clutch plates.

Clutch Springs:

All bevel twins use the same clutch spring. A popular home ‘bodge’ to try and cure slipping clutches was to fit springs from a 450 Ducati single. These 450 springs have thicker steel in the coil springs, which makes them ‘stiffer’.

Clutch springs can also lose tension over a period of time and use and again, most 

manufacturers will list a minimum length of the clutch spring.

These are the main culprits when it comes to ill performing clutches on bevel drive Ducati engines. Of course you’ll always get the usual suspects, like sticking clutch cables, seized or partially seized clutch levers, rusty pushrods and so on. Every part has to be at its best for the clutch to work as designed.

Vee Two Clutch Video - Click Image Below to Watch

Getting to the clutch

To get to the clutch you must first remove the rear cylinder header pipe so you are able to remove the clutch cover. If you have an electric start motorcycle, you will also need to remove this as well. There are two distinct electric start systems on bevel drive engines with wet clutches. One has a chain drive from the starter to the idler gear (Bosch ignition engines), and the earlier engines have a bendix style starter arrangement, much like a car.

It’s best practice to disconnect the battery before removing the starter and associated wires.

Once this is done, and any other ancillary parts, like gear levers for example, are removed you can remove the clutch cover from the engine.

If your basket and hub is not worn enough to warrant replacement, you simply undo the six screws holding the springs into the pressure plate and the spring cups. Once the springs are removed, you can pull the pressure plate off, which then allows all the clutch plates to be pulled away from the basket and hub, ready for the new clutch.

Basket and hub

If you need to replace the basket and hub you will need to remove the clutch hub nut which holds the basket and hub on. This is a regular left hand thread. Originally the factory fitted a tab washer, and if this is still in place you will need to bend the tab so you can undo the nut.

If you have a clutch tool, you can hold the hub with that and use a socket to remove the nut. If not, you can hold the hub by hand and use a rattle gun and socket to do the same job. This works well.

If your engine has the original ignition rotor, you will need to remove that first before there is enough room to remove the clutch basket. This is another left hand thread nut and again the rattle gun is your best friend here. Once this is removed you can simply pull the hub and basket away from the mainshaft of the gearbox.

To fit the new basket you will need to remove it from the primary gear, as they are bolted together. The bolts may have thread locker on them and may need some heat to weaken the thread locker. Once these bolts are removed, clean the bolts and threads with a white spirit of some kind so new medium thread locker can be applied when you bolt the basket and primary gear together. It’s worth noting here that there is a bearing in the primary gear, and it’s best practice to replace this at this time. Also ensure you do not misplace the thrust washer that sits on the mainshaft behind the primary gear. It is essential this remains in place as one of its purposes is to line up and mesh the two primary gears correctly.

Once this is all done you can refit the basket and primary gear by simply slipping it on to the mainshaft, then slide the clutch hub on. Vee Two does not use the alloy tab washers as originally fitted by Ducati. We find the soft alloy used in the manufacture of these washers cause them the deform and allow the nut to loosed. While the nut does not come off it allows the basket and hub to move slightly which causes undue wear to the parts. We use medium thread locker to hold the nut on, and torque it to spec. Ensure all parts are clean of oil and residue before using the thread locker.

Vee Two uses the Italian made Sureflex clutches and there are instructions in the kit which highlight which order the plates go in. The first plate in is usually different to the rest, as is the very last plate before the pressure plate is fitted. You must follow these instructions.

It’s a matter of timing

Once the clutch plates are fitted, you can fit the pressure plate, which is timed. By timed, we mean it can only go on in one position, where you can access all the clutch hub posts. You can then fit each of the six spring cups. On the pressure plate there is an indentation in each of the six holes where the spring cups sit. There is also an indentation on each of the spring cups. You need to ensure each indentation is lined up with each other so the spring cups sit flat against the pressure plate. If this is not done, the pressure plate will not sit flat, and it is essential for them to sit flat for correct operation.

The next step is an important one. You need to ensure the clutch plates disengage evenly. If not, your clutch will not operate as smoothly as it could.

Holding the clutch plates into and onto the basket and hub is the pressure plate, springs and spring cups. The even movement of the pressure plate and clutch plates, all things being in good condition, is controlled by the clutch springs. These are held in place by short screws and washers, which once screwed in hold the springs over the posts of the clutch hub. You pull the clutch lever in, it pulls the clutch cable and clutch arm, which in turn pushes the clutch push rods to further compress the clutch springs and push the pressure plate away from the clutch basket and hub, therefore releasing pressure on the clutch driving plates.

You can check if all of these parts are working in harmony by gauging how evenly the pressure plate moves outwards when you pull the clutch lever in. The easiest way to check this is to have the clutch cover removed and look out how the pressure plate moves out.

If it is uneven you can sometimes swap the clutch springs around, as some may have slightly more or less tension than its mates. This could fix the issue or if not you can place an extra small washer underneath the head of the bolt and the first large washer which sits on the outside diameter of the clutch spring. When the clutch spring screw is tightened down and seats this extra small washer, which slides down the inside of the clutch spring and seats up against the clutch hub post, you will have the effect of having less pressure on the spring by essentially making the hub spring pos longer by default.

This is usually an easier process than is explained on paper. Once the clutch pressure plate is deemed to be operating evenly and smoothly, it’s time to adjust the free play on the clutch arm. In the centre of the pressure plate there is an adjusting screw and lock not. This is what adjusts how much free play there is at the clutch arm.

You loosen the lock nut and screw the adjuster in our out, with the aim to have around 5mm movement at the upper end of the clutch arm, so there’s no engagement left between the clutch plates when it’s disengaged.

It’s sweet

Now it’s time to put the clutch cover back on, electric start bits and bobs if your engine has them, and go for a ride.

You can watch the full video in the links below or in this article.