Technical Knocking noise from passenger side rear.

[Astura]

I have read lots and lots of threads on this and it seems like a common problem.
I have just purchased my 500 with 111k miles on it, recently had a new back box fitted. Before I purchased it the guy advised me there was a knocking noise and that he thought it was the bushes on the rear axle, so.. without thinking fully I bought a brand new rear axle - iv had that fitted but on taking the old one off which was battered to hell and the cups that hold the coils had started to rot through we noticed the bushes were completely fine, so this ruled that out with making the noise.
On fitting the new axle we noticed that there was a slight gap between where the shock sits so filled that with spacers to prevent any noise.
The mechanic then noticed that the rear back box exhaust mount bush had completely persisted so has cable tied it up until the new bush comes.
The rear shocks have been replaced before I owned it so the only thing I can think it is is this rear bush on the exhaust.

It doesn’t make the noise when I start up, it doesn’t make the noise really when I drive slow, if I pull up a steep hill it has a good old rattle and if I go over any types of bumps it makes a knocking/rattle noise.

Any other suggestions other than what IV tried above what the noise could be?
Thanks

 

[Baglady1990]

How is the long exhaust pipe? Is that in good shape ? Does it have all its brackets? Are you sure it’s not the back box making the noise?

 

[John202020]

Grab a hold of the exhaust, shake it around up down side to side etc, see if it makes a noise ? A missing rubber new(replace all of them) could easily cause a knock.

 

[chris3234]

Gap where the shock fit?
There shouldn't be a gap the metal bush in the shock should fill all the gap in the lower shock mount

 

[John202020]

I would put a fiver on this position for the gap near side? Hence my washers.

 

[onecleanfinger]

Check if the handbrake cables are nice and snug in the small curved steel clamps that are welded onto the rear axle. If it's loose it can bump and sound like a suspension component/bush.

Also, when the previous owner fitted the new rear shocks whoever did it might have torqued up the mounting bolts with the wheels in the air. That stresses the shock absorber bushes when the weight of the car is on the ground. Correct procedure is on ePER. It includes setting the correct ride height at the rear before torquing the bolts up ,