My mates beater, a 406 coupe judders when he pulls away in 1st. It happens on about 80% of starts and only happens for the first few meters. It happens fairly irrespectively of how many revs or what he does with the clutch.

the clutch is new.

Anyone any ideas what the cause might be?

 

If the clutch is new.....

Whoever did it might not have mounted the pressure plate properly.
Alternatively the shaft splines might be worn.
Theres a contaminant on the lining.
His mounts (engine or gearbox) might be loose.

Personally if I'd had someone else fit a new clutch and the car was juddering, I'd be back there to get it fixed by them.

 

Didn't use the clutch alignment tool correctly?