Re: Stiff clutch on GT 1.9 JTD. Why?
I suspect the GT has, by design, a high pedal load. The root cause of the high load in the GT JTD is probably the high clamp load clutch cover required to provide sufficient clamping onto the clutch plate in diesel/high torque applications. There are a number of ways of reducing the impact of this at the clutch pedal, but it is not always possible or desirable to incorporate these (I'm talking about the design stage, rather than aftermarket). Hydraulic/mechanical ratio can be changed but the changes to pedal travel/clutch pedal load characteristics (lack of feel) plus cost and packaging issues usually mean there is a compromise between clamp load/pedal load/pedal travel/feel and wear characteristics (amongst others).
The GT has a significantly higher pedal load than, for example, a BMW 120D and (without measuring) I would reckon it would fall outside of what would be acceptable to BMW. Alfa probably have a higher clutch pedal load limit than BMW and significantly higher than the Japanese manufacturers.
Sorry, for rambling......