AU Vibration

[AUbigfoot]

Ok this is a fairly hard thing to explain so bare with me here. Lately when driving I have noticed an inconsistent vibration noise from my car and it seems to be coming from the back right. At first I thought it might be something like a screw loose on the number plate as that is the kind of sound it is making. I tightened all screws on the number plates, checked the spoiler as well to make sure it wasn't anything there. I have looked all over the car and cannot seem to track it down so I took it to a suspension centre for a look under it. The bloke there said that he has had the same trouble with his falcon and still cannot track it down. Everything under my car is fine and it hasn't got any issues. We took it for a drive and cruised to 60. Without breaking I down shifted to 2nd and after a second the rattle made it's appearance for about 2 seconds then disappeared again. I'm trying to pin point some other times that it happens, but the suspension bloke is in the same boat and can't pin point a specific time, location or driving style.

We decided maybe to post up on here and see if anyone else is having the same or similar problem as even he can't figure it out on his own car.
The ideas that we came up with are: bent heat shielding, air getting in behind something at the front and passing the noise down so it sounds like it's at the rear, something loose on the shell of the car.

I'm lost...

[blueoval]

It could be a number of anomalies Ken.

Im guessing its not wheel bearings. When did this noise start occuring? Before or after the wheels were fitted?

[AUbigfoot]

it was before the wheels were fitted.

[blueoval]

could possibly be the exhaust vibrating or touching something its not supposed to.

[GK]

Get a mate to sit in the back, while you recreate the driving conditions to make the noise. At least you might be better able to tell what it is.

Have you checked the speakers in the parcel shelf, or for things in the wheel well, or to see if the boot garnish was loose? Could it be a loose or rusted exhaust?

GK

[Beer Baron]

I had the same sort of noise and it turned out to be the muffler. The only way i got the noise to happen was to put it on a 2 post hoist and drive it with my foot on the brake to load it up and get some one with a stethascope to poke things.

[AUbigfoot]

Cheers for the suggestions so far guys. I will try and get someone in the back to have a better listen for me. I hope it's not the exhaust as it's rather new but there's no harm having a deeper look at it all.

Beer Baron: That sounds rather complex. What exactly was it with the muffler, or was it just general prodding that stopped it?

[scrivens]

I'll second the rear muffler mount. Had a very similar noise from one of those big rubber O rings vibrating at a narrow rpm range. Unhooked it and remounted it and that fixed it.

[blueoval]

considering that the exhaust system is aftermarket, its possible that the extra noise/vibration that it makes will make the body or other parts of the car make more noise than it used to.

[AUbigfoot]

I'll tinker with that today then and have a little look around. I tried to get it to do the noise again last night and I couldn't get peep out of it which is why I get so frustrated at it, it's just sporadic!