VR Vibration

Has anyone had this problem? My much loved VR (LPG) occasionally vibrates so badly over 80 KPH it stops the car and sounds like a helicopter is over head. No mechanic or dealer can tell me what is the problem cause it only happens now and then. Mainly from a cold start. I changed the Harmonic Balance which seemed to help for a time but now is a bad as ever.

Once I stop the car I can then usually drive off again vibration free. Has anyone had this type of problem? Thanks

Mervm123

Automatic or manual gearbox?

Have you ever had the driveshaft centre bearing checked or replaced? It could be the centre bearing OR, if it has been replaced, not fitted in the correct spline and put the driveshaft out of balance.

Thanks.
It's an automatic geerbox. I will have the centre bearing checked.
mervm123