9.2 - | Crankcase assembly: crankcase halves

1 | Circlip

2 | Timing belt driveshaft

3 | Alternator-side crankcase half

4 | Bearing

5 | O-ring

6 | Circlip

7 | Bearing

8 | Screw

9 | Retaining plate

10 | Bearing

11 | Seal

12 | Bearing

13 | Seal

14 | Bearing

15 | Bearing

16 | Clutch-side crankcase half

17 | Spacer

18 | Screw

19 | Bush

20 | Seal

21 | Bearing

22 | Circlip

23 | Bearing

24 | Roller bearing

25 | Screw

26 | Screw

27 | Screw

28 | Seal

29 | Circlip

Parts catalogue

Timing system
Crankcase halves

Important
Bold reference numbers in this section identify parts not shown in the figures alongside the text, but which can be found in the exploded view diagram.
Separation of the crankcase halves

Operation | Section reference
Remove the engine from the frame | N 1, Removal of the engine
Remove the lubrication system | N 2.1, Removal of the oil pump
Remove the cylinder head assemblies and the timing parts | N 4.2, Removal of the timing belt covers
Remove the cylinder barrel/piston assemblies | N 5, Removal of the cylinder/piston assembly
Remove the alternator-side crankcase cover and the alternator assembly | N 8, Flywheel - alternator
Remove the gauze pickup filter | D 4, Changing the engine oil and filter cartridge
Remove the clutch-side crankcase cover | N 6.2, Removal of the clutch-side crankcase cover
Remove the clutch assembly | N 6.1, Removal of the APTC clutch
Remove the engine starting system | P 3, Electric starting system

Use two screwdrivers to remove the snap ring (1) from the timing idler shaft (2) on the clutch side crankcase half.
Notes
Take care to avoid scoring the surface of the shaft while removing the circlip.
Unscrew the crankcase screws (25), (26) and (27) from the alternator-side crankcase half (3).
Unscrew the two screws (25) on the clutch side crankcase half (16) near the vertical cylinder.
Re-use the alternator-side crankcase cover or a service cover with puller 88713.1749. Secure it to the crankcase half using several of the original screws and begin to separate the crankcase halves by turning the central pin of the tool.
Tap the end of the gearbox output shaft with a plastic mallet to separate the crankcase halves.
Notes
Take care not to lose the shims on the shafts and on the selector drum.
Remove the gearbox shafts (A) and gearbox selector drum (B) from the crankcase (Sect. N 7.2, Gearbox assembly: gearbox shafts).
Drive out the crankshaft (C) using a plastic mallet and taking care not to lose the shims (D).
Remove the timing belt driveshaft (2).
Recover the O-Ring (5) from the communicating oil way between the crankcase halves.
Overhaul of the crankcase halves
Carefully examine the engine crankcase halves.
Check that the surfaces of the crankcases are perfectly flat using a reference surface. Check that the bearings (4) and (23) are in good condition. Note that main bearings must always be changed in pairs (refer to the procedure below in “Main bearings”).
Notes
When overhauling an engine it is good practice to renew all the crankcase bearings.
Renew the bearings (10) and (15) on the ends of the gearbox output shaft and the timing belt driveshaft bearings (7) and (21).
After having renewed the gearbox shaft bearings (14) and (12), secure them in the crankcase with the spacers (17) and the retaining plate (9) fixed respectively with screws (18) and (8).
At each overhaul it is recommended to renew also the oil seal (13) located between the bearing (12) and the chain-side crankcase half: lubricate the oil seal (13) with denatured alcohol and install it in the crankcase half, orienting it as shown.
At each overhaul it is recommended to renew also the oil seal (11) located outside the bearing (10) and the oil seal (20) outside of the bearing (21).
In the event of renewal of needle roller bearings (24) and oil seals (28) on the swingarm pivot shaft, lubricate the seats of the bearings and the lips of the oil seals with the recommended grease.
Install the inner oil seal (28) as shown in figure (E) ansd seated against the circlip (29); the outer oil seal must also be installed as shown in figure (E).
Use a suitable drift (see figure) to install the oil seals (28) and roller bearings (24).
Check that the oilways are free of restrictions or clogging.
The bearings (24) are to be installed with writing (F) oriented as shown in the figure
Check the condition of locating bushes (19). In the event of evident signs of distortion or excessive assembly clearance in their bores, remove the locating bushes using appropriate tools.
If the removal of the bushes (19) from the casing proves difficult, use a left-handed thread tap to force the bushes out.
Important
The bushes (19) must always be renewed when they have been removed using the above procedure.
Overhaul of the main bearings
The main bearings have are of the angular contact type with offset inner races so that the balls transmit loads from one groove to the other along straight lines at an angle to the axis of the bearing. Angular contact thrust bearings are designed to withstand combined loads (radial and axial loads).
Bearings of this type can bear thrust loads in one direction only. In fact, under the action of a radial load inside the bearing, an axial force is created that must be counterbalanced by an axial force acting in the opposite direction; that is why these bearings are generally fitted back to back in pairs.
To renew the bearings proceed as follows:

- | heat the crankcase half in an oven to 100 °C;

- | remove the bearing using a drift and hammer;

- | install the new bearing (while the crankcase is still hot) keeping it perfectly square in its seat using a tubular drift that only bears on the outer ring of the bearing;

- | allow the parts to cool and check that the bearing is securely seated in the crankcase.

Important
On worn engines, the bearing holder may no longer be a tight fit in the crankcase half.
Check that the interference fit between the crankcase and the bushes, with bearings (4) and (23) installed, is not less than 0.03 mm, otherwise the crankcase halves must be renewed.
Important
After installing new main bearings, shim the crankshaft as described in the paragraph “Shimming the shafts” and “Reassembly of the crankcase halves” in this section.
Reassembly of the crankcase halves
The crankcase halves must be in good condition and perfectly clean. The mating surfaces must be perfectly flat and free from burrs.
Refitting the clutch-side crankcase half
The following parts must be present on the internal side of the crankcase half:
The output shaft end bearing (15): apply grease to the bearing rollers. Fit the inner race (A) removed previously from the bearing. Apply grease to the inner race.
The input shaft bearing (14), secured with bolts (18) and retaining spacer (17). apply the recommended threadlocker to the screws (18) and tighten them to the specified torque (Sect. C 3, Engine torque settings).
the roller bearing (21) with retaining circlip (22) at the timing belt driveshaft.
Refitting the alternator-side crankcase half
The following parts must be present on the internal side of the crankcase half:
the double race ball bearing (10) supporting the selector fork shaft.
Apply threadlocker to the screws (8). Fit the retaining plate (9) to the gearbox output shaft bearing (10) screwing the screws (8) fully into the chain-side crankcase half.
Notes
The bearing retaining plate must be positioned so that the countersunk side is facing upwards.
Tighten the screws (8) to the specified torque (Sect. C 3, Engine torque settings).
The gearbox input shaft end bearing (12) with the inner spacer (B): apply grease to the bearing rollers.
Fit the inner race (A) removed previously from the bearing. Apply grease to the inner race.
The main bearing (4).
The ball bearing (7) with circlip (6), in correspondence with the timing belt driveshaft, oriented si that the closed side of the plastic roller cage faces the crankcase half.
Notes
None of the bearings except the main bearings have an obligatory assembly direction. it is good practice to install the bearings so that the side bearing the writing is facing upwards.
Shimming the shafts
Before assembling the crankcase halves, calculate the shims required to obtain the correct end float of the crankshaft and gearbox shafts.
To determine the correct shim thicknesses proceed as follows.
Shimming the crankshaft
After fitting the new main bearings, proceed as follows to determine the total shim thickness “SA”:
measure the distance “LA” between the bearing contact surfaces on the crankshaft;
measure the depths “LA1” and “LA2” corresponding to the distance between contact surface of the crankcase half and the contact surface of the inner race of the bearings;
add a pre-load of 0.30 mm to prevent excessive crankshaft end float when the crankcase halves are at their normal operating temperature.
This gives:
SA=LA1+LA2+0.30-LA.
To calculate the thickness of each shim note that:
SA=SA1+SA2
where “SA1” and “SA2” represent the shims for the clutch-side crankcase half 1 and the alternator-side crankcase half 2.
Considering the alignment of the shaft, this gives:
SA1=LA1+0.15-LA/2;
and finally, the second shim thickness: SA2=SA-SA1.
Practical method for determining crankshaft shims
In addition to the above procedure, the following is a practical shimming method, providing a guide on how to calculate the crankshaft shim thicknesses accurately.
Install a shim (R) of minimum thickness (1.90 mm) on each side of the crankshaft to prevent contact between the crankshaft web and the engine block.
Install the crankshaft and assemble the two crankcase halves.
Fit three M8 screws (25) into the holes shown in the photo and tighten to the specified torque (Sect. C 3, Engine torque settings).
Place a dial gauge (T) with magnetic stand on a support plate fixed to the crankcase.
Bring the stylus into contact with the end of the crankshaft and set the dial gauge to zero in this position.
Insert a lever (L) between the crankcase and the crank web and force the crankshaft towards the dial gauge.
Note the dial gauge reading. This is the crankshaft endfloat. Add a preload of (0.30 mm) plus the thickness of the shims used (1.90x2=3.8 mm).
Divide the resulting value by two to obtain the thickness of the shim packs to be installed at either end of the crankshaft.
Notes
After assembling the crankcase, the crankshaft should turn with some interference in the new bearings.
Shimming the gearbox shafts
To establish the total shim thicknesses to be installed on the input shaft “SP” and the output shaft “SS”, proceed as follows:
measure the dimensions “LP” and “LS” on the input and output shafts (for the output shaft add shim thickness “R” of 2.3 mm;
measure the depth corresponding to the distance between the contact surface of the crankcase half and the contact surface of the inner race of the bearing for the input shaft (“CP1” and “CP2”) and for the output shaft (“CS1” and “CS2”);
given that end float should be in the range 0 to 0.15 mm, we will take the optimal value of 0.15 mm, which gives:
SP=CP1+CP2-LP-0.15 and SS=CS1+CS2-LS-0.15.
To determine the thickness of each single shim pack, note that:
SP=SP1+SP2 and
SS=SS1+SS2.
Where “SP1” and “SP2” are the clutch and chain side input shaft shimming values respectively and “SS1” and “SS2” the corresponding values for the output shaft. This gives:
SP1=CP1-64-0.075 and
SS1=CS1-64-0.075, so that
SP2=SP-SP1 and SS2=SS-SS1.
Notes
The method described for the crankshaft can also be used to calculate the shim thicknesses for the gear shafts.
Shimming the gearbox selector drum
To determine the total thickness “ST” of the gearbox selector drum shims, proceed as described below.
Given that:
LT1 = clutch-side crankcase half depth;
LT2 = chain-side crankcase half depth;
LT = gearbox selector drum shoulder.
Given that the end float should be 0 10 to 0.40 mm
and taking the mean optimal value of 0.25 mm.
This gives: ST=LT1+LT2-LT-0.25.
Given that ST=ST1+ST2
we obtain ST1=LT1-59-0.125, so that ST2=ST-ST1.
Notes
The method described for the crankshaft can also be used to calculate the shim thicknesses for the gearbox shafts.
Reassembly of the crankcase halves
Install the timing belt driveshaft (2) in the roller bearing (21) in the clutch-side crankcase half.
To avoid damaging the oil seal (20) on the timing belt driveshaft, protect the threaded end of the shaft with the special protective cap 88700.5749. Dampen the oil seal (20) with alcohol and fit it on the timing belt driveshaft, seating it against the roller bearing (21).
Fit the circlip (1) in the groove on the shaft and remove the protective cap.
Notes
When refitting used components, make sure that the inner races (D) of the gearbox shaft bearings are fitted to the correct bearings and have not been left on the shafts.
Mesh the gearbox shafts and install them on the clutch-side crankcase half with the calculated shims.
Install the forks of the 1 st- 4th and 2nd- 3rd gears (F) in their respective grooves in the secondary shaft driven gears.
Notes
The two selector forks are identical.
Install the 5 th- 6th gear selector fork (G) in the input shaft driven gear.
Install the selector drum (P) in the crankcase with the previously calculated shim thickness.
Fit the pins (Q) in the previously installed selector forks.
Fit the shimmed crankshaft into the clutch-side crankcase half, positioning the connecting rods (B) in correspondence with the relative cylinder housings.
Check that the two locating bushes (19) are correctly installed.
Grease O-ring (5) to hold it in position and install it on the oil way connecting the two crankcase halves.
Important
Make sure that the connecting rods (B) are correctly positioned in the respective cylinder bores. Incorrect positioning of the connecting rods at this stage will inevitably lead to the need to re-open the crankcase.
Apply a uniform and continuous bead of DUCATI liquid gasket (A) to the mating surfaces of the crankcase halves, going around all the holes as shown in the figure.
Bring the crankcase halves (3) and (16) together, tapping with a rubber mallet in the area of the shafts if necessary.
Prepare the crankcase screws, and insert them in the alternator-side crankcase half (3); note that the screws are of different lengths.

Ref. | Qty | Description
25 | 7 | M8x75 mm screws
26 | 5 | M6x35 mm screws
27 | 1 | M6x75 mm screws

Progressively tighten the crankcase screws until fully seated, starting with the screws of the largest diameter (M8) and following the order indicated.
Insert two M8 screws (25) in the clutch-side crankcase (16).
Tighten all the screws to the specified torque (Sect. C 3, Engine torque settings).
Ensure that the crankshaft can be turned with a degree of interference with the main bearings (the crankshaft should have a pre‑load of 0 15 to 0.20 mm); check also that all the parts you have fitted are free to rotate or move correctly.
Proceed to install the oil seal (11) and the spacer with the O-ring in the gearbox output shaft using the specific tool (T).

Operation | Section reference
Refit the gauze pickup filter | D 4, Changing the engine oil and filter cartridge
Refit the clutch assembly | N 6.1, Refitting the APTC clutch
Refit the clutch-side crankcase cover | N 6.2, Refitting the clutch-side crankcase cover
Refit the engine starter system | P 3, Electric starting system
Refit the alternator-side crankcase cover and alternator assembly | N 8, Flywheel - alternator
Refit the cylinder barrel/piston assemblies | N 5, Refitting the cylinder/piston assembly
Refit the cylinder head assemblies and the timing parts | N 4.2, Cylinder head assemblies: timing belt covers/timing system
Refit the lubrication system | N 2.1, Refitting the oil pump
Install the engine in the frame | N 1, Refitting the engine