Well after alot of playing around and testing, I seem to have stopped the noise. I turned the bolts around the "wrong way" Basically the bolt has a smooth section of shank which the inner sleeve of the link pin joint is supposed to sit on and the threaded part of the bolt passes through the mounting hole on the chassis. The thread must have been catching on the mounting hole. I turned the bolt around so the smooth part of the shank is now sitting inside the hole in the chassis. No noise so far....