Knocking from under front of the car.

[benh999]

Right folks help time please. 

Since picking up my G40 she has an annoying knock that seems to be coming from underside around the bulk head area forward. I've not yet been under the car so am after things to look for.  It only happens when the car pulls/stops suddenly or as I like to put it "kangaroo's"...  the noise only happens on forward/backward movement, not up down etc.

[breadman]

Could be a knackered rear engine mount allowing too much movement or the exhaust hitting the brace bar?

[wozzaG40]

Could be a track control arm mate

[scotsjohn]

Me too; shagged exhaust hangers are first suspects here.