Noise on 'throttle back'

[MRpunchinella]

Sorry if this should be in 'Tek';

seems to be a great deal of reverberation within cabin on throttle back when the car (S1 135 'improved spec') is being driven 'positively' seems especially so on motorways seems to be coming from floor or /and behind cabin.

when driving hard then lifting off or dropping gears to take junction or roundabout there is very distinct and loud reverberation in cabin - much to the alarm of female passenger......

I know that they all can do this, but was wondering if it could be tamed? could a very thin (and its lightweight) rubber (it aint rubber but my dad used it in engineering to absorb shock and reverb) strips be fitted between undertray and body and between panel behind cabin....if you know what i mean? Or is this 'Drrriiing' noise something im stuck with? Apart from that, car is amazing.

thanks

Punch

[Rich H]

TADTS.

Mine is quite booming during heavy braking, the gearbox doesn't help as they are all noisy on overrun.

IIRC it's the floors resonating. The later cars have a slight fold across the floor panel to reduce this. You might be able to reduce it by putting some of the sticky sound damping stuff under the seats. Apparently you don't need much, just a piece in the middle of the panel. There is a long and arduous thread on this on SELC*CK if you can be bothered.

Failing that wall to wall axminster carpet!

[Shug]

I also get this if I bodge on the undertray. Try also loosening all the undertray bolts, positioning it correctly (push it fully forward) and re tighten (starting with the big bolts)

Mine is doing it after my last tray-off and I've not been arsed sorting it yet - I guess you can tighten a wee bend in it if you're in a rush, causing something to vibrate.

Yes, it does sound like it's in the cabin

Other than that, go with Rich's post and whack some sound deadening under the seats.

[MRpunchinella]

Thanks....will try this. Have considered fitting carpets Do you know of any sound deadening sticky carpet stuff via post? Might check classic car etc. the gearbox whine doesnt bother me at all and the rest of the noise is ....good.....so far as im concerned, would just like to tame the reverb.....

Thanks for quick post

[Rich H]

I've got a bit, I'll see if I can find it. Dunno how sticky it still is. IIRC Sanjoy has some too.

[tuscan_thunder]

I get it when there's stuff in the net behind the seats - it reverbarates off the tub. sounds like the exhaust's about to fall off sometimes. usually just CD cases etc

[MRpunchinella]

Removed rear undertray and riveted one strip alu plate 1" broad on the horizontal and two short similar strips running perpendicular to previous, both on the underside of tray. Zero reverb or rattle no - no matter the abuse (and ive really tried ). Just a thought.

Punch