Knocking sound from front left side on my BMW X5 M50d first thought it might be a bush or bearing problem but had all replaced including bottom and top arms plus drive shaft but it's still there I think now it's a drive shaft problem because in slow traffic  I get a clunking sound as if something is loose.

Hi Malcom.

have you broken a spring? 
 

Morning Malcolm

Welcome to the Forum

First check is does your car have VDC suspension ? Next check what was its year of manufacture to check model E70 F15 or F85 ? All 3 are possible for a 2014 registered car.

If E70 the top mount has for want of a better description a couple of spongy washer like pads, they just fail and you get a knock sometimes when turning easy check under the centre nut of the top mount there is a big washer under that is the sponge/fibre pad easy to see and not hard to change. F15 and F85 don't have them but worth checking the top mount anyway 

If it's a rotating knock also worth checking the front drive shaft 

Good Luck tasty motor by the way 

Dave