Hi on my 209 Range Rover sport 3.6 there are two big weights right at the back of the chassis on both sides and they are able to move, a bit like balance weights , does anyone know what they are for please .

They are harmonic mass dampers. They are used to tune the chassis' response to vibrations etc. They basically make the car a nicer place to inhabit. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

They are Harmonic Damper weights supposed to help stop resonating noise/vibrations. They did move enough at one point on my car to knock on the bumper under sharp braking and made it sound like a knocking suspension, just wrapped a bit of foam rubber to them and cured that. There are a couple of similar lumps of metal bolted on to the chassis underneath the front door post area although the are fixed, assume they are for a similar purpose, same as the small metal blocks blocks bolted to the front calipers on the TDV8 Brembos.

Cheers
Col

Lovely thanks for the info I was wondering what they were there for now I know thanks.