FLYWHEEL HOUSING - PRIMARY GEAR The flywheel housing can be detached from the engine-transmission unit while the power unit is still installed in the car, but is more easily performed once the engine/transmission unit has been removed.


1. Detach the flywheel and clutch assembly, following the relevant steps given under the appropriate heading in the 'CLUTCH AND MANUAL TRANSMISSION' section. The engine oil must also be drained out of the power unit.
2. On 1275 GT models, unbolt the engine breather from the top of the flywheel housing.
3. Unbolt the clutch slave cylinder from the flywheel housing and place to one side out of the way. It is not necessary to disconnect the hydraulic pipe.
4. Fit tape or foil over the splines of the crankshaft primary gear to protect the flywheel housing oil seal as the housing is removed. This will be unnecessary if the seal is to be renewed anyway. A proper protector sleeve is available as a special tool, but the makeshift solution above Will do the same job if a bit of care is used.
5. Knock back the locking plate tabs and remove the flywheel housing securing bolts and nuts . Note the respective positions of the nuts and bolts to ensure correct fitment on reassembly.
6. Withdraw the flywheel housing from the engine/transmission unit. It may be necessary to tap the housing free as it is located by two dowels on the transmission casing. Remove the housing gasket.
7. The needle bearing of the idler gear shaft and the outer race of the gearbox input shaft roller bearing will come away with the flywheel housing.
8. Withdraw the 'C' shaped thrust washer locating the primary gear on the crankshaft, and slide off the backing ring, primary gear and inner thrust washer .

Inspection and Overhaul - Primary Gear Oil Seal

The primary gear oil seal in the flywheel housing should be renewed if it shows any signs of wear, damage or oil leakage. If the engine has covered a large mileage, a new seal should be fitted as a matter of course.
Lever the old seal out of its location in the housing, taking great care to avoid damaging the housing bore.
Lubricate the new seal with grease or engine oil and press it into position in the housing. The proper seal installer tool is shown in , but it should be possible to press the seal into position by hand or by tapping it carefully on its outer edge. In this latter case, support the underside of the housing beneath the seal aperture while installing the seal.
It should be noted that the flywheel housing oil seal can be renewed while the housing is still in position on the engine/transmission unit. The procedure for this operation is fully detailed under the appropriate heading later in this section.

Flywheel Housing

As noted during the removal procedure, the needle bearing of the idler gearshaft and the outer race of the gearbox input shaft roller bearing are located in the flywheel housing and will come away with the housing when removed. If either of these bearings require to be renewed, they should be replaced as follows--
To remove the gearbox input shaft outer race from the housing, first extract the circlip retaining the race in the housing. Expand the housing by immersing it in very hot water, then withdraw the race from the bore. A special extractor tool, such as that shown in , will be required to remove the race. Press the new race into position in the housing, using a suitable size of drift . Refit the bearing retaining clip.
The roller bearing itself can be pulled off the gearbox input shaft after removing the retaining circlip. In most cases it should be possible to lever the bearing off the shaft, but the proper puller tool is shown in . Fit the new bearing onto the shaft and tap into position, bearing only on the inner diameter of the bearing. Secure the bearing with the retaining circlip.
A suitable extractor tool, such as that shown in , will also be required to withdraw the idler gear shaft bearing from the housing. Tap the new needle bearing into position, bearing only on the outer diameter of the bearing. The use of the proper installer tool, shown in , will ensure that the bearing is installed to the correct depth in the bore.


1. Ensure that the mating faces on the flywheel housing, cylinder block and transmission casing are clean and free from old gasket material.
2. If the idler gear or idler gear thrust washers have been changed, it will be necessary to check the idler gear endfloat and adjust if necessary as detailed under the 'TRANSMISSION CASING' heading later in this section.
3. If the crankshaft primary gear or thrust washers have been changed, the gear end-float should be checked and adjusted, if needed, as detailed below. It should be noted that the primary gear end-float can be checked with the flywheel housing in position on the engine/transmission unit as shown in , but if the end-float requires adjustment the flywheel housing oil seal must be removed together with the primary gear to change the front thrust washer. A new housing oil seal must be fitted on reassembly.
a) Fit the primary gear front thrust washer onto the crankshaft with its chamfered side against the crankshaft register (See . Fit the primary gear and backing washer and secure in position with the 'C' shaped rear thrust washer.
b) Measure the primary gear end-float with feeler gauges between the backing -washer and the end of the gear .
c) The gear end-float should be 0.0035 - 0.0065 in (0.089 - 0.165 mm). If the end-float is outside these figures, select a thrust washer to bring the end-float within the specified limits. Thrust washers are available in five thicknesses from 0.110 to 0.120 in (2.80 - 3.05 mm) in 0.002 in (0.05 mm) stages, The thickness of the existing thrust washer should be measured with a micrometer to determine its size for comparison.
d) Very early engines were fitted with a primary gear which had an oil feed provided to the bushes. These are identifiable by the additional oil seal fitted to the flywheel. The running clearance is slightly less for this type of gear, being 0.003 - 0.006 in (0.076 - 0.152 mm). Thrust washers in this case are available only in three sizes, from 0.125 to 0.131 in (3.17 - 3.32 mm).
e) Refit the primary gear assembly with its selected thrust washer and recheck that the end-float is now within the specified tolerance.
4. Fit the protector sleeve or tape over the primary gear splines to protect the flywheel housing oil seal.
5. Two pilot bars, made up and screwed into two bottom tapped holes in cylinder block as shown in , will help locate the flywheel housing in position and take the weight off the primary gear oil seal.
6. Pack the transmission input shaft bearing rollers with high melting point grease to help prevent them tilting as the flywheel housing is refitted. Also ensure that the idler gear thrust washer is correctly in position on the end of the idler gear shaft .
7. Position a new housing gasket on the engine/transmission face and ensure that both locating dowels are fully in their holes.
8. Lubricate the primary gear oil seal and fit the flywheel housing,into position. Tap it fully home onto the locating dowels, then remove the two pilot bars if used.
9. Secure the housing in position with the retaining nuts and bolts, using new locking plates. Ensure that the bolts are refitted in their original locations - this is most important as the oil gallery in the cylinder block may be damaged if a long bolt is fitted in the right-hand upper position.
10. Tighten the flywheel housing nuts and bolts to their specified torque of 18 lb ft (2.5 kg m), then secure with the locking plate tabs.
11. On 1275 GT models, refit the engine breather to the flywheel housing.
12. Refit the clutch/flywheel assembly as detailed in the CLUTCH AND MANUAL TRANSMISSION section.
13. Finally, refill the engine/transmission unit with oil as detailed in the ROUTINE MAINTENANCE section.