Ok a mate just called me in panic. He was driving his supra at 50m/h (he is a very decent driver) when a hard knocking started from under the car at the rear. He described it as a hammer being hit from under the backseats or somewhere behind the frontseats with a bit of grinding. It is a constant noise and the harder he drives the louder it gets. Also releasing the gaspedal brings the noise. To get the noise a bit under control he kept a bit of presure on the gaspedal, so not giving too much gas but not letting it loos either, that's when there is the least banging noise. He drove the car home at 10 m/h this way 5miles further. Back home he went to ly down under the car and says the cardanshaft (or how do you call it in English) seems ok, or maybe he just can't see it.
What could this be? He says the car is undrivable and the noise gets overwhelming. Could this be the differential? Has anyone had this same issue? I know him very well he drives like a grandma so it cant be he forced something.
Any advice very welcome !