Loud bang from passenger side wheel / suspension. Cause?

[guest1870]

Hi,
my '07 1.4SE manual, (which I bought only 8 weeks ago) with 13 k miles has developed a loud bang from the left side wheel going over pot holes.
It is OK over normal road undulations but hitting say, a 50mm deep pothole , particularly if on the brakes, produces a loud single bang. It sounds like two fairly large pieces of metal coming together and is a bit scary. I thought the wheel had sheared off the first time I heard it.
I took the wheel off and couldn't see anything obvious wrong, no loose bolds or perished rubbers.
I put the car into my local tyre and shock absorber place and they said that the only thing they could find wrong was a worn wishbone bush. They could not be certain that replacing it would fix the problem however. The cost would be £157 (only £25 of which is labour, the part must be expensive) so I've held off.
Clearly I need to go back to the dealer I bought it from, but he is 40 miles away and I want to be forearmed with some info before he "takes a look" at it. My fear is they will just say there's nothing wrong or that its "wear and tear" and not covered by the warranty.
Can anyone confirm if a wishbone bush would make this noise or is there some other common fault I can check out?
The first mechanic said that big car dealers will have a "shaker plate" to help them find suspension faults. Anyone heard of this?
I'm a bit gutted , I bought a Jazz because of the reputation for reliability and here I am 8 weeks in with a fairly hefty repair bill looming.

[guest1844]

Sounds like a bush. A big bump and the stress on the wishbone moves it a lot and it rattles on the through-centre bolt. Surprising on car this new though. It might be the shock absorber, but the fact that braking makes it worse suggests a wishbone bush as it would be under heavy forces when braking, with a split second relief as the wheel goes light on the way down the hole  (the fore bush will be under outwards tension, the aft bush under inwards force). Does it skew the steering a tad?

The course of action is the same - take it back. I can't see they can argue about it - bushes should not wear this soon. It would be an MOT failure.

[guest1870]

Thanks Bazzer,
your reply makes sense. The sound seems to be coming from closer to the centre of the car than the immediate wheel area. This would be the area where the wishbone bush is.
I called the dealer to report it and he will take a look.
Thinking about this I don't really think it should be a third party warranty claim. The dealer took my money, if the car has a fault this early then he should be putting it right.
I'm sure the warranty specifically will exclude "wear and tear" on suspension consumables in any case.
His opening gambit was "yes, the roads are in a shocking state" possibly suggesting that I had stupidly driven the car through some grand-canyon sized pothole.
We'll see how I get on.