Manual - Chapter 1 Engine

7. Dismantling the engine unit: removing the bellhousing and auxiliary drive shaft components

  1. If the engine unit is in the frame, remove first the gearbox and final drive (Chapter 3 - Gearbox), the alternator (Chapter 10 - Electrical) and the ignition HT coils (Chapter 6 - Ignition). Remove the clutch (see Chapter 2 - Clutch), but while the housing is locked to permit the retaining nut to be unscrewed, slacken also the bolt securing the alternator drive flange to the auxiliary shaft. Remove the crankshaft cover. See Section 6 - Cam chain (engine front) cover.
  2. Owners will now have to devise some means of supporting securely the frame rear end and the engine at the same time. Note that when the frame/bellhousing mounting bolt is removed the engine will pivot, however slightly, on its two front mountings thus causing a risk of damage to other components and problems with alignment on reassembly. Only secure supports can prevent this.
  3. If the frame rear end is hanging from an overhead support, as described in Chapter 8 - Final Drive, great care must be taken not to jar the frame while the bellhousing is removed. Note that jacks should not be used to support heavy components for any length of time; they are for lifting only. Use car axle stands, blocks of wood or similar to hold the engine and frame securely at the required height.
  4. When the machine is securely supported remove the bellhousing mounting bolt and any shims that may be fitted.
  5. If the engine is removed from the frame temporarily refit the clutch housing and lock it as described in Chapter 2 - Clutch to permit the alternator drive flange retaining bolt to be slackened. Remove the bolt and withdraw the drive flange, noting that the 0-ring and thrust washer behind it may be dislodged.
  6. While in practice the flange was found to be a fairly slack fit and was easily pulled away by hand, it may require a sharp tap from a hammer and a soft metal drift or a wooden dowel (to avoid damaging the shaft) on the auxiliary shaft rear end to jar it free. BMW state that a two-legged puller, with an adaptor to protect the shaft end, is required to remove the flange; it will probably be necessary to grind down the puller claws so that they will fit between the flange and the bellhousing.
  7. Remove the bellhousing/crankcase retaining screws. These are Torx screws, size T30, and will require the use of a suitable key to remove and refit them. Torx keys are available at most specialist tool shops and some auto accessory shops; it is useful to purchase a key that is attached to a socket so that a torque wrench can be used to fasten them.
  8. When all the screws are removed, tap the bellhousing sharply with a soft-faced mallet to break the seal and withdraw it, noting the presence of the two locating dowels. Check carefully that the starter idler shaft and the auxiliary drive shaft are not dislodged with the bellhousing.
  9. Carefully pull the starter idler shaft out of the crankcase and note exactly how the spring behind it (if fitted on early 100 models) is fitted before removing it. Withdraw the auxiliary drive shaft as a single unit.

7.5 Lock crankshaft to permit removal of alternator drive flange retaining bolt

7.7a Bellhousing / crankcase retaining screws are of ....

7.7b .... Torx type - special key required for removal and refitting

7.9 Remove auxiliary drive shaft as a single unit