A warped clutch plate can cause the shudder that you are describing. This occurs when they have been overheated by excess slipping. Another cause could be oil or grease on the clutch plate, but that usually goes away after a while. If not slipping, you could drive on the clutch a lot longer before replacement, but it sure takes the fun out of it. I have 150,000 kms. on the clutch in my truck and it is still fine, so I would say that 30,000 is early. GlennMc.