I dropped the gearbox out on the weekend and my thoughts proved correct. The friction material on the pressure plate side of the clutch disc had broken away from the rivets allowing it to fly out and contact the rim of the flywheel. Despite being the original clutch (dated 4/90), it had not worn out over the almost 240,000km it has travelled. Pressumably it was just fatigue which had taken its toll on the friction material. Neither the pressure plate nor flywheel were scored and I was thinking this would not be such a costly job.

Everything was a bit greasy (although the clutch friction surfaces were dry) so I figured a new crankshaft rear main oil seal and gearbox input shaft seal would be in order. This meant removing the flywheel and it was then that I realised all was not well. The secondary mass of the dual mass flywheel was not sitting parallel to the primary mass. A check revealed that the secondary mass was actually free to come away as the eight pins that should hold the flywheel together had sheared. Twisting the secondary mass revealed that there was noticeable lash due to the broken pins before the pressure of the springs between the two masses took effect. In use all that was holding the flywheel together was the release bearing pushing against the pressure plate. A bit of a worry considering that the flywheel and clutch as an assembly weighs in at over 22kg (around 50 pounds) and can spin at up to 6000rpm. Also amazing that the car remained as driveable as it did for as long as it did. This probably explains the clutch shudder I have experienced in the three and a half years I have owned the car.

I am now waiting for prices and availability of all the parts and I am not looking forward to what it might cost. Thankyou to those who offered suggestions and I will keep you informed of progress.

Greg

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.