I read that they have had

solid flywheel non OEM detroy the rear main bearing cap after stretching the bolts. Regards

Peter

Edited by Car on 26/04/2009 at 08:58

If the engine breaks when a solid flywheel is fitted its the hallmark of a rubbish design. This modern stuff that blows up if it is not given a preferred flavour of fully synthetic oil is just a crock of s#1t. One can surmise that when a solid flywheel is fitted it might be a good idea to fit a damper pulley to the crankshaft. Of course a LOT of trouble is caused by miserly drivers who slog their engines in fifth gear in the hope of saving fuel. Shattered clutch plates with protruding buffer springs are the result of such abuse.

As to buit in obsolescence, I sometimes wonder how long it will be before ECUs have a real time clock that kills the car when it reaches a certain age.

As to flywheel bolts breaking, the better types will surely be 12.9 tensile rating flange head bolts. They are of course subject to considerable heating from the clutch. There is so much heat at that part of the engine that PTFE or Viton oil seals are commonly used. The makers instructions to use oil when assembling the parts seems highly suspect however and if problems have occurred before it seems far wiser to use a high temperature high strength engineering adhesive. The clamping force on the flywheel when the bolts are tightened well hard can be of the order of thirty tons and hopefully there will be dowels as well. Torque-to-yield is fairly standard these days as if the bolts are torqued to a lower figure money has been wasted as a similar clamping force could have been obtained with a cheaper bolt.

Often the reason for flywheel bolt failure will be the result of the owner continuing to drive the car when there has been a smash-up in one cylinder. A hydraulic lock caused by water in a cylinder can also do it.