Although the Octavia has a decent noise profile from factory, I decided it would be worthwhile attempting to soundproof it a little more. The usual culprits, the boot and rear seat, were first in line. The large metal surfaces in the boot had only some small pieces of deadening material on them from the factory, sounded like a drum when tapped, especially the hump above the gas tanks. Treated them with a layer of CTK Premium 2.2mm butyl mats. I also identified a potential source of rattle under the rear seat, marked in the second picture. The part of the trim extending below the seat has a plastic rivet going through it, but it's not tightly secured against the metal. Tapping lightly on the edge caused it to rattle, so I snuck the edge of the butyl mat below those parts, tightening them up.

 

Adding insulation in these locations has already improved a lot of the noise originating from the back, particularly by eliminating a lot of the "thump" you hear when driving over small bumps or holes in the road surface.

 

Next step will probably be the doors and boot lid.

 

 

Edited 22 August, 20223 yr by Jorgeminator

Nice project.

How do you remove the rear seats? You just need to pull them up?

36 minutes ago, TheUltraRunner said:

Nice project.

How do you remove the rear seats? You just need to pull them up?

The Isofix anchoring points have to be pushed downward to release the shroud from the anchor. You can lift the cover to see how it's supposed to come out.

The front part releases with a firm pull upwards. The clips holding the front in place may break or not, so either get some spares or hope for the best. Mine stayed intact.

When both the front and back are loose, push the whole seat a centimeter backwards and lift upwards, to release it from it's notches.

The cable for the weight detectors is on the left side, be sure to disconnect that one before lifting the seat any further, same applies for seat heating if present.

Edited 22 August, 20223 yr by Jorgeminator

Thanks!

 

One more question. Do you need to prep the surface before putting on the mats?

22 minutes ago, TheUltraRunner said:

One more question. Do you need to prep the surface before putting on the mats?

It's recommended to clean the surface with some isopropyl alcohol for example, but for surfaces like this where the mat is pulled down by gravity I don't consider it mandatory. I just went over the area with a dry rag and the mats stuck really well.

Amazing project, it's also a thing i'd love to do to my Octavia, the road i take to work every day is a mess and it has developed so many rattles on the door panels that it's driving me crazy.

 

The plastic door panels are a mess on my car and definitely my biggest complaint about it, and now to top things off the steering wheel airbag started developing a really loud rattle as well. My car hasn't even got 20k km on the clock and it's already a rattly mess...

 

Anyway, keep us updated i'd love to see what you do so i can try the same eventually. In my case i'm thinking of eventually put some foam pads on the inside of the door panels, they're very hollow and squishy and there's always plastic noises when driving over even the slightest bumps.

54 minutes ago, Jack_Dangerous said:

Amazing project, it's also a thing i'd love to do to my Octavia, the road i take to work every day is a mess and it has developed so many rattles on the door panels that it's driving me crazy.

 

The plastic door panels are a mess on my car and definitely my biggest complaint about it, and now to top things off the steering wheel airbag started developing a really loud rattle as well. My car hasn't even got 20k km on the clock and it's already a rattly mess...

 

Anyway, keep us updated i'd love to see what you do so i can try the same eventually. In my case i'm thinking of eventually put some foam pads on the inside of the door panels, they're very hollow and squishy and there's always plastic noises when driving over even the slightest bumps.

Will start doing the doors soon. Today I did the boot lid. Added butyl mats in the cavities with a lot of flat surfaces. The trim got some butyl mats and acoustic foam on top.

 

 

That acoustic foam is exactly what i'd love to put in my door panels, i'm sure that alone would make a world of difference.

Proceeded to the doors today. Started out with the rear right since I've had an annoying rattle coming from that one. Upon removing the door card I discovered there's no way of getting to the outside panel anymore, without removing the window and the whole lift assembly.

I applied 2.2mm butyl mats to the most resonant parts of the inner frame.

The door card didn't have any sort of deadening material on it, so I applied butyl on the worst sounding surfaces and topped everything off with 15mm CTK WaveFix acoustic foam.

 

I did a customers 87 Audi Coupe GT with £2k worth of Dynamatt and liner, the car was 20-mm lower after...😁

On 24/08/2022 at 22:56, Jack_Dangerous said:

That acoustic foam is exactly what i'd love to put in my door panels, i'm sure that alone would make a world of difference.

Did the passenger front door today. Mostly the same procedure as the rear doors, except the front doors have two "crash clips" as VW/Skoda calls them. They are both located on the rearward facing part of the door. The bottom one is released by taking out a screw behind a small lid that pops open easily using some thin enough item. The top one is a one way clip that can't be "pulled" out unlike the other rivets. Instead it slides open when you lift the door card out of the window channel, no idea trying to force it out by pulling, it will break for sure.

My 10€ plastic trim removal set has proven itself invaluable as I've been taking apart the trim in different places. No broken clips yet. Only thing broken are the small "hooks" on the inside of the door handle cover, but they don't really contribute to anything, the cover stays tightly in place only with the push-in clips.

Worth adding: The front passenger door also had an additional control module (made by Continental). One of the connectors was so loose in its socket it would rattle just by giving it a little nudge. All doors have had plastic holders that rattle when the wiring looms move. All rattles disappear when these are tightened up with either foam or a piece of butyl in the right place 🙂

If I remember, I will take pictures of these areas when doing the driver's door.

Edited 27 August, 20223 yr by Jorgeminator

That's it. Doors, trunk and rear seat done. As promised, here are some pictures of the front door.

 

Overview

Crash clip 1, screw type.

Crash clip 2, releases by lifting the door card.

Anchor on door card for crash clip 2.

Door control module. The connector on the right side (brown/green) was sliding back and forth and rattling.

Another potential source of rattle.

Pressure sensor for the airbag system. This should be left connected and untouched.

Door card finished. Didn't put any material close to the LED projector as it has a heatsink that needs some air around it.

Edited 28 August, 20223 yr by Jorgeminator

I am interested how much did that cost you?

Does it make a lot of difference?

 

I once did that to a golf 7.5 and it helped a little but not as much as I expected.

 

14 minutes ago, Tadejm said:

I am interested how much did that cost you?

Does it make a lot of difference?

 

I once did that to a golf 7.5 and it helped a little but not as much as I expected.

 

Around 300€. The difference is easily noticeable, especially at highway speeds. All the annoying rattles are gone as well. Doors have a better thud to them when closing them from the inside.

I still had 10 sheets of butyl mats left over, so I did the underside of the bonnet today. Can't say it made a huge difference to the cabin noise, but opening and closing of the bonnet sounds a lot firmer now, not as tinny as before.

 

Oh, and I added some felt pads to the boot lid stoppers. These stoppers are the newer, supposedly fixed ones, but the lid was still clunking slightly when driving over bumps. The felt pads made it quiet.

Edited 29 August, 20223 yr by Jorgeminator

So you have removed the original padding under the bonnet? Is it safe to have butyl mats inside the engine bay?

12 minutes ago, TheUltraRunner said:

So you have removed the original padding under the bonnet? Is it safe to have butyl mats inside the engine bay?

I removed the factory insulation pad only temporarily while installing the deadening mats. The CTK mats are specified for temperatures up to 150°C. It will never get remotely that hot behind the cover.

 

 

Edited 29 August, 20223 yr by Jorgeminator

Did you notice any fittings in the rear door cards for ambient lighting?

 

 When the octavia was first revealed, it had ambient lighting in the front and rear doors. They must have quietly dropped it from the spec. 
 

I wonder if it will ever  be possible to retro fit it?

 

i think the golf has it in the rear doors. 

1 hour ago, Benjybobs said:

Did you notice any fittings in the rear door cards for ambient lighting?

 

 When the octavia was first revealed, it had ambient lighting in the front and rear doors. They must have quietly dropped it from the spec. 
 

I wonder if it will ever  be possible to retro fit it?

 

i think the golf has it in the rear doors. 

Nothing in the rear door cards. Judging from and comparing with the front doors, retrofitting would be difficult if not impossible. There are just too many permanently fixed points that have to come apart for that, unfortunately.

Are you going to do wheel arches? It seems that in Octavia tire noise is the biggest contributor to general noise level. It's not nearly as bad as in Leon (both 5F and latest one), but still it is something to improve.

28 minutes ago, Felix2021 said:

Are you going to do wheel arches? It seems that in Octavia tire noise is the biggest contributor to general noise level. It's not nearly as bad as in Leon (both 5F and latest one), but still it is something to improve.

Yeah I'll second that. Road noise from the tyres was my biggest issue from (nearly) new. Until I did a tyre change it was awful on anything other than a very smooth surface - and they are like hens teeth!!

 

When I changed my tyres lower DB rating was a major factor, and yes I know its measured as a drive past reading, but if each tyre is 6 / 7 DB quieter isnt that 25DB less overall? 

 

Nice thread BTW, I'm suprised how much is going on behind the door panels!! 

Unfortunately tire noise is the biggest issue on majority of "cheaper" cars. I've tested Merc CLA, as i was considering it. It was even i bit worse than Octavia, which was very surprising. In general noise level in CLA is comparable to O4.

But that's why i'm thinking about wheel arches. I think that would bring much bigger improvement, than other parts.

2 hours ago, Felix2021 said:

Unfortunately tire noise is the biggest issue on majority of "cheaper" cars. I've tested Merc CLA, as i was considering it. It was even i bit worse than Octavia, which was very surprising. In general noise level in CLA is comparable to O4.

But that's why i'm thinking about wheel arches. I think that would bring much bigger improvement, than other parts.

I've considered doing the front wheel arches from the inside, potentially adding some mass to the footwell floor as well. I'd like to do two layers with butyl mats under and for example 6mm closed cell foam on top, but I don't know if the carpet has enough play for the foam to fit. Not sure how the footwell trim comes off yet, I'll have to read the manual and have a look. 

Had a quick look at the passenger footwell. There is already 10mm dense foam covering the wheel arch and firewall from the inside. The horizontal part of the floor in front of the seat felt empty when reaching under the carpet, so that's probably one area to focus on.