Centre under tray noise

[cnikonpete]

Hello, I have a 2012 Jazz bought in January. It has an annoying noise which I’m pretty sure comes from the undertray situated in the middle underneath.
When driving over uneven road surfaces there is a soft knocking noise which at first I thought came from the front passenger door but turned out to be false . I started looking under the car and could simulate the noise by banging the undertray.
After pushing hard foam into the undertray gaps it reduced significantly, but only seems to quieten down when it feels like it.
It’s one of those noises that once heard you cannot ignore. The tray is bolted to the car I’ve checked the rear two bolts and they are tight,front ones,I’ll have to lift the car.
Anyone had similar?

[Keekster71]

It might be the undertray.  You will need to jack it up and check the clips for any broken.  Another possibility is the exhaust.  On my last, mk1 Jazz, I found the after market exhaust did not fit well and used to knock on the underside of the car.  I sorted it by using a  cable ties to reduce the movement in the exhaust mounting rubber.

[cnikonpete]

Thanks, doesn’t really sound like that,but hadn’t thought of checking exhaust, I’ve used foam pipe insulation to firm up the undertray ,it isn’t helped by our atrocious roads!

[desthemoaner]

 I have a 2013 Jazz 1.4 ES, 62k miles.

It sailed through the MOT on September 24th, but just a few days later I became aware of a "clunk" at low speed which at first seemed to be coming from the back of the car. I checked the security of seats, spare wheel etc etc and found nothing awry,  but since then I've concluded that its actually originating from underneath. Could be the same thing as yours, perhaps, but I haven't yet had a look at the undertray.

The car is going in for a rear brake check (the MOT tester said that the rear brake effort was a tad low, but didn't add it as an advisory) at the end of this month, so I'll ask the garage to check for the "clunk" at the same time.

[Lord Voltermore]

I once had a 'clunk' on my  2007 Yaris that I could have sworn came from the rear.  I turned  out to be a broken coil spring at the front!  (Which I subsequently learned is a 'known' fault on the Yaris)

[cnikonpete]

Thanks gents,
I thought at first it was the passenger door, then I put foam pipe insulation between the undertray and floor,everything I try has an effect,then it returns!
I tried the spare and its cover etc,all the same.

It’s not big potholes that makes it noisy, more like some uneven surfaces,which down here ,is every minor road.
I undid the two nuts at the rear, but can’t see what’s at the front, I’ve only got a trolley jack,so am a bit wary about going underneath.
The exhaust seems firm and isn’t touching. Suppose it could be a cracked coil spring,but I think bigger bumps would make it louder.
I hate noises!!

[cnikonpete]

Think I have found my irritating noise,nothing to do with under tray, found if passenger pushed on front passenger window, the noise went!
Sprayed the window runners with silicone spray,which had a dramatic effect, now going to repeat with white grease spray
Will be so happy works