The BMW K75 & 100 from 1983

Manual - Chapter 2 Clutch

5. Reassembly

On 100 models only, fit the thrust washer to the front of the clutch housing. On all models, tap the new pilot bearing (if disturbed) into the output shaft rear end. Apply a smear of the specified lubricant to the bearing.
Insert the housing into the output shaft and press it fully into place. Fit the new a-ring and the shouldered spacer (spacer flange outwards, towards the gearbox) followed by the new retaining nut. Lock the housing by the method used on dismantling.
On 100 models tighten the nut to the first stage torque wrench setting to settle the housing and a-ring then slacken it fully and tighten it again to the (final) second stage setting. On 75 models tighten the nut to the setting specified. Refit the wire ring to the housing.
For the next part of the operation have an assistant hold each component in place while the next is fitted. Some lubricant will be required; BMW recommend Optimol Paste PL, Staburags NBU 30 PTM compound, or Uni Moly C220 Slip Agent. If these cannot be obtained locally, seek the advice of a BMW dealer. Degrease all components carefully before applying new lubricant and apply only thin smears; do not allow any lubricant on to the friction material.
Fit the diaphragm spring to the housing wire ring applying a smear of lubricant to all points of contact between the two and to the three support arms securing the spring centre. Ensure that the spring is the correct way round; refer to the accompanying photographs and illustrations to check this, or examine the spring closely, looking for polished wear marks where the spring contacts the pressure plate. With the spring the correct way round refit the pressure plate. Ensure that the balancing marks are correctly aligned; if BMW's own marks are used, the pressure plate mark must be 120' away from that on the housing. If your own marks were made as recommended, align the pressure plate mark with that of the housing. Apply a smear of lubricant to all points of contact between the spring and pressure plate.
Fit the friction plate to the pressure plate, ensuring that it is fitted the correct way round; the centre boss extended end should face the gearbox.
Refit the cover plate, aligning the balancing mark as described above. Apply a smear of lubricant to the cover dowels to prevent corrosion. Before the screws are fully tightened, the friction plate must be centred. The easiest way of doing this is to push the gearbox input shaft into the clutch assembly and to line it up with the dowels protruding from the rear of the bell housing. If this is not possible it will be necessary to acquire the BMW centring tool No. 21 2 670 or to make up a substitute for it, as shown in the accompanying illustration (see Fig 2.4). Insert the tool into the friction plate centre splines, passing the long nose into the output shaft pilot bearing. The BMW tool now incorporates a bridge which fits on the bellhousing locating dowels to ensure perfect alignment. With the friction plate aligned, tighten the cover plate bolts or screws evenly and in a diagonal sequence to the specified torque wrench setting.
Apply a smear of lubricant to the pushrod and pilot bearing and to the splines of the gearbox input shaft and friction plate centre before refitting the gearbox.