Hey guys and gals.

My back end is vibrating like crazy when the sub are crankin.

I don't know where to start dampening the cars back end.

I have a look on the net for help but only saw one for sedans only.

Any ideas mate since all you hear is vibrations outside.

start with the actual hatch then maybe the rear quarters and then the boot floor.

Have owned a swift in the past - here's a couple of things i did:


Fill small/tight spaces with expanding foam.
If you have a thin piece of ply as the floor of your hatch (i did), take it out and replace it with a 12mm mdf board, cut to fit snuggly so it doesn't move around.
Sound Deaden the rear hatch area (take carpet out and SD everything, including spare wheel well).
sound deaden your inner skins (the plastic cover things you pull off your boot door and walls etc.) - you may also need to fill these in with foam.

Oh and don't forget to put some rubber washers under your license plate screws to prevent plate vibrations...

what model astra?

have you checked to see if it's the number plate holder if you have one???

SDing can lose SPL, I advise testing after you do each panel.

SD will make the car sound better, but output can be lost. What is your goal?

Phil

HOW CAN U LOOSE SPL SDING

???????????????????????? same q

makes me wonder why people sound deadin spl cars

Hello people!!!!!!

SOUND DEADENING.

DEADEN. n: to make quieter

SD material absorbs acoustic energy, the last thing you want in an SPL car.

Often it lowers the resonant frequency, which is also bad.

Sometimes it helps (due to strengthing panels), often it doesn't. That's why I said to test in between the application of each piece.

Phil

hello!!!!

Smart ass! LOL

Phil

nah man im bein serious how can u loose spl thru sding.
not bein a smart ass

Yeah all the rattles and resonance adds db, take that away and it sounds much better, but to a simple Microphone can be quieter.

But honestly, if you arent competing who would ever want to hear rattles? I prefer music over sound.

Sound deadening lowers the ambient noise/ road noise as well, so you dont need your stereo up as loud to overcome road noise at speed.

But number plate is usually the first and foremost for rattles outside the car, a simple strip of closed cell foam does wonders.

Dont think the smart ass comment was aimed at you mate.

And Phil already gave a basic explanation as to how SD can affect SPL.

It isn't always the case, but plenty of competitiors have experienced losses thru adding SD.

Sound deadening's main aim is to stop resonance. especially through viscoelastic transfer.

imagine a resonating sheet of metal With sound deadener on it inside a car with music playing. At a microscopic level the sound deadener (usually bitumen/tar based) is moving then returning to its previous state, (like if you were to push your finger into your skin and let it go, your skin will deform initially then return to it's previous state) thus absorbing energy that would usually turn into sound (resonance) and turning it into heat through this viscoelastic transfer.

If the aim is gaining db, you dont want this transfer to happen. You want as much energy being turned into sound, and as little going into heat and movement.

thanx guys.

I used to rear load my subs in my old laser (subs and port facing backwards) and when i deadened the hatch i lost almost .5db

Lost alot of rattles to i might add.

Here's the smart ass.

LOL

Phil

lol, thats me

anyway, back on topic, now it is explained that way, i understand....what if everything was lined with a solid material, like mdf......would that help??

yes, if you reinforce the whole car (ie. extreme class) then your spl will go up as you have limited loss of noise outside the cabin. but in db drag you are limited to what you can do to the car in each class division...
extreme cars you can barely hear the sub's outside the car with the doors shut.

I am interested to enter the next Doran's sound - off at end of April. I thought If I took my car down as is, then it would just "buzz" like crazy.

My aim is to get a good reading for SPL purposes.

My woofers are facing the rear for maximum loading effect with only 100 rms per woofer.

I rang Doran's and they told me they can do the car for around $200.00.

I understand that dampening the car will make it less noiser outside but I don't want to loose SPL.

I guess I can just lower the volume then just sound like a big bumble bee coming down the road hee hee!!

Start with your licence plate mate.

hey im in a similar situation, i drive an astina hatch (94 pop up lights)

anyways my number plate doesnt rattle!!! but my boot does!!!!

when i push up against it (not down, but towards the front from behind) that stops the rattling

would that be loose connections or will i need deadening?

im not running a huge system, just a 4500 thunder powered by a 250w rms monoblock