AO Silver Member
Join Date: Nov 2003
Location: United Kingdom
County: Perth and Kinross
Re: 156 clutch question
In the old days, all flywheels were a single lump of metal. It was machined to shape, a ring gear for the starter motor stuck on, and then balanced.
A dual mass flywheel is as the name suggests. That is there are two parts to it. The outer part (and nearest the engine) has the ring gear on it. The inner part (nearest the clutch) is located to the outer part by a bearing. There are springs to allow a few degrees of relative rotation. This damps out a lot of torsional vibration (the engine is smoother). It is most commonly used on diesel engines.
DMF are renowned for questional reliability. The bearing wears, and it allows the inner plate to wobble. This can produce noise, vibration or clutch judder. It can even produce engine management issues because the crankshaft speed sensor senses the crankshaft speed is fluctuating. It is easy to check (once the gearbox and clutch is out of the way), and any mechanic should be competent to do this.
[SIGPIC][/SIGPIC]Drive sideways- life's too short not to
Slip-sliding my way through winter. On four wheels and two.