Clutch movement

[mgcjag]

Hi All.....Quick question for you.....standard diaphram clutch...assumeing its new....how much movement of the thrust face is needed to release the clutch.....i dont have a problem its just something that came up in discussions. ..Steve

[PeterCrespin]

It will slip after about a millimeter of movement beyond hard contact and be completely free after another millimeter or two assuming the friction and pressure plates are totally flat. This translates to about a quarter inch at the pushrod clevis and most pedals adjusted and operated to give more stroke than that

[mgcjag]

Thanks Peter...Somehow i knew you would know......i was thinking 3mm but it didnt sound enough....all the best....Steve

[PeterCrespin]

It’s difficult to quantify because with incompressible solids the friction is hugely dependent on clamping force, not movement. So technically my answer was wrong because the clutch will slip before the plates separate at all, just because the diaphragm spring pressure is reduced. The spring is what bends/unbends and the OP specified movement at the thrust face (i.e. the ‘far end’ of the spring) so a few millimeters is as good a guess as any in the absence of a full geometry analysis for zero pay!