[Mike]

I live in Northamptonshire where we have lots of pot holes and noisy road surfaces.  After reading about other people complaining about Road Noise, and their experiments with different brands of tires they mostly came to the conclusion that yes the Hankook Tires are noisy but the car probably lacks some sound proofing.  I have also been reading about noise reduction on car audiophile websites.  I used to wonder if some of the noise was down to a poor seal around the hatch but its not.  My car is a lot quieter now, heres what I've done.  Sorry no photographs.

1) Fitted the sound deadening pad underneath the bonnet.  This helps to reduce engine noise, front tire noise (the suspension can also cause inner bonnet panels to vibrate and the noise can travel through the bonnet and windscreen).  This also helps to stop the paint oxidising.

2) After fitting the bonnet pad I noticed that the road noise was mostly coming from behind.  I had an idea after reading that most soundproofing companies use expanding foam in the A and B pillars.  I didn't fill these but just behind the rear seats is a channel that runs along the width of the car where the child seats can be mounted.  Both ends run through and behind the wheel arch trim panels, this isn't soundproofed in any way.  So I filled this channel with expanding foam, lots of holes that help injecting the foam.  Don't use too much as it keeps expanding!  No problems with water or drainage here.

3) I then cut and placed some car soundproofing felt in the boot / hatch area.  My car has a space saver wheel and the back isn't level, it rises up in a L shape where the Child seat anchor points are.  I then bought some gell backed carpet to cover both the original carpet and soundproofing felt.  This has almost made the boot level so its easier to put larger boxes in the back.  When done with care it looks very professional and much better than the Genuine i30 mat that didn't really fit my 2011 model!

4) Under the rear seat is a metal cover for the fuel pump.  The carpet under the seat has some factory soundproofing felt but the metal plate has none.  I'm not sure how air tight it is anyway.  I cut an old yoga exercise mat (4mm thick) so that it tucks under the carpet and completely covers the plate.

5) With the hatch carpet removed I can see daylight through the floor.  The back of the car has many plastic plugs that are for a different model, Premium?  They are not needed for my car and no screws are fitted.  These plastic plugs are similar to raw plugs that expand when a screw is used.  My first thought was to fill these with a pan head screw.  In the end I used some quality outside silicone sealant and pushed it into the holes.

6) While I was in that area I planned to fit some sound deadening pads to the rear wings behind the trim panel.  Hyundai had got there before me!  The trim panel itself also appeared to be well made and had a felt pad on the back.   There were some unused holes near the inner rear wing not too far away from the boot light / rear seat belt.  I could see that these holes were there for cable clips or similar used on a different model.  I covered the RH ones with some fabric tape.

6b) While the side hatch trims were accessible (by removing the parcel shelf supports) I pushed some speaker wadding down the plastic rear wheel well trims.  This is below where the rear seat back rest locks into place.  I used a 30cm rule to push it down.  Its best to keep this away from the seat belt and seat locking mechanism.  I have read horror stories about people using this inside the doors and jammed up the window motor and gears!  Also put a little under the front plastic wheel well trims.

7) There was a lot of space around the outside of my space saver tire.  I used some folded hand towels to fill the gap.  If ever I get a puncture I might want to kneel on these anyway or wipe my hands.

8) I already have Hyundai foot well mats.  This must help absorb some sound and help deaden the floorpan.

9) When I fitted my Pioneer TS-E1702i / s speakers I noticed that the aluminium inner door skin rang when tapped.  I wasn't sure what to use here and didn't want to mess with sound deadening paint so I used fabric tape again.  This lowered the skins resonant frequency and tightened up the loose bass of the stereo.

So after all of the above the car is much quieter.  The tire noise of rough roads can still be heared but its now muffled.  I can now live with the 16" Hankooks and don't have to buy the Pirelli P6 Four Seasons until next year or maybe the year after.  I believe that the rear noise was mostly coming through the floorpan, and being reflected by the rear window.  Fitting quieter tires is obviously an easy solution but not the cheapest. 

After pulling a lot of the car apart I have found that it has been well made, and they have put some thought into soundproofing. I read on a car audiophile forum you only need a small gap to allow 90% of the noise through.  Maybe this is the reason why so many people complain about road noise in a well manufactured car

Hope the above helps.   

[Asterix]

Hi Mike

You have been busy. Glad to hear that your effort helped to reduce the noise.

The sound deadening pad underneath the bonnet is standard in my crdi, but maybe I should check up on some of the things you mention, as I also think there is too much road noise in the i30.

I have tried with different makes of tyres, but that did not make any great difference.

[Dazzler]

Excellent post Mike Thank you... Noise makes such a difference on long trips and is one of the reasons we ended up trading our 1st i30 on a much quieter Toyota Camry Hybrid (where were you in August 2010?) 

[Shambles]

  sensational post Mike - thanks for going to the trouble of documenting your efforts 

Hope you don't mind, but I'll move this to the "how to" section as a useful guide for anyone looking to see how they too could improve their noise levels

[2i30s]

brilliant post mike.  i may implement some of those mods into my cars. 

[Phil №❶]

Mike, Did you have any difficulties with trim removal / replacement, not everyone is as confident at ripping their interiors apart. Sounds (pun) like your efforts were worth it & thanks for posting. 

[Ugly Mongrel]

Very thorough post, Mike..Well done

[Mike]

Mike, Did you have any difficulties with trim removal / replacement, not everyone is as confident at ripping their interiors apart. Sounds (pun) like your efforts were worth it & thanks for posting. 

No problems.  Just take your time.  If you want access to the top of the rear wing panel trims, first remove the parcel shelf.  Then the plastic shelf supports, theres a plastic cover over one of the bolts.  Use a small flat blade screwdriver at the top of the plastic bolt cover as that's where the clip is.  The bottom of the plastic cover has a strap that stops it from being completely removed, so don't pull it from there.  If the small flat blade is carefully pushed in at the top it will help to push down the clip and it will be easier to gain access.
Rear door trims have two screws (unlike the front) that are covered by a simple plastic plug.  Then they just pull off, be carefull around the top where the stock tweeter / wing mirror adjuster is.  Maybe when refitting the door trims you could remove the tweeter first, they just pull off.

Another thing worth mentioning is that the lower the profile of tire the noisier it is.  Car reviewers say avoid the lower profile wheels for this reason, it also makes a harsh ride.  So stick with the 15 / 16"

Hyundai  offer even larger wheels.  You will feel more of the bumps in the road as there is less rubber to absorb the inperfections and noise.  I did consider buying some nice 15" alloys but the offset was 45 which is only just about ok.  Also it would have meant extra expense and insurance costs although 15" tires are less expensive.

Hyundai 16" alloys are begining to show up on auction websites.

[2i30s]

thanks for the further how to tips mike. 

[Phil №❶]

Mike

We are not affluent people, so our cars represent a large investment of our resources. B4 I go undoing things left right & centre, I need to know what difficulties you have already discovered. Thanks for your quick reply. 

[Mike]

Mike

We are not affluent people, so our cars represent a large investment of our resources. B4 I go undoing things left right & centre, I need to know what difficulties you have already discovered. Thanks for your quick reply. 

Me too.  I will be paying for the car for some years.  The only difficulty was with the amount of expanding foam, I used a bit too much as it takes a few minutes to expand.  So don't use too much.  It can be wiped away with a cloth, when tacky a bit of methylated spirit will help.  Any sticking up above the holes can be snapped off when dry (or cut).   This area will be covered when the boot carpet is refitted.

The boot carpet is easily removed as its only held in place by two strips of Velcro.

The cars are designed to be made quickly on a production line, they come apart at about the same speed and ease but it does help knowing where all the clips are.  A slow gentle approach and a keen pair of eyes prevent damage.  The only trim I completely removed were the door cards and tweeters.  Fitting the Pioneer speakers is more complicated but not really part of this noise reduction Topic.

I guess more can be done, but like you I didn't want to remove the seats and other trim on my new car.  I don't feel I did that much.  Some people completely strip their cars and even remove the roof lining.  Then sound proof paint can be fully applied. People also say that they spray stone chip on the floor pan to stop it from drumming.

This is just what I have done in my limited spare time and budget.  If anyone feels uncomfortable about pulling their car apart then maybe its best that they google for extra help or take it to a good independent Car audio specialist.

[Phil №❶]

Cheers 

[Doggie 1]

Thanks for a great post.
Noise is probably the single biggest complaint I would have with my i30 (there aren't many  ) so that info is most useful.
Dave

[syecadelic]

Awesome work, only thing with expanding foam would be warranty issues, even if nothing is directly affected, your dealer could be a tw4t.
Recently sound proofed the boot of my car, although never done the bar that runs behind the passenger seats that you mentioned.
Used all newspaper to fill the gaps between the rear quarter panels etc, and used Rattlemat as well, very pleased with the outcome, also filled the boot lid with news paper, as it rattled due to the subs, door panels and wheel arches will get done in the future maybe

[Dazzler]

Hi Sye, Could newspaper harbour moisture though and cause corrosion?

[syecadelic]

Hi Sye, Could newspaper harbour moisture though and cause corrosion?

hmm.. an issue i never thought of. :/ as long as it doesnt happen within the next couple of year it will be all good
and if it starts I can easily pull it out and claim under the anti-perforation warranty, just dont tell my dealer

[2i30s]

Hi Sye, Could newspaper harbour moisture though and cause corrosion?

hmm.. an issue i never thought of. :/ as long as it doesnt happen within the next couple of year it will be all good
and if it starts I can easily pull it out and claim under the anti-perforation warranty, just dont tell my dealer

[stochastic]

I've done a significant amount of acoustic research though none thus far related to cars.  I love this thread already and it's made me want to get going on silencing my ride a bit too - great job Mike.

For soundproofing, the primary goal would be to seal off any air gaps into the cabin - sound travels through air, stop the air. 
The second step would be to create multiple 'air locked' layers around the cabin - this is fairly ridiculous for the entire cabin to be encased in a second sealed layer but it would provide the theoretically best sound-proofing (one could add discreet layers to the boot or a door panel to assist however - air space in between is very important). 
The third goal would be adding mass to the cabin - but this directly reduces gas mileage. 
The fourth would be to use sound absorption materials anywhere in the process (certain places will be more effective, but that's a complex subject).  Contrary to popular belief soft materials aren't always best for this, the towels around the spare tire mentioned above will do little other than providing something for your knees to kneel on while you change the spare.  The crumpled newspapers probably won't help very much either (though they may possibly create layered air pockets, though unlikely).  The best option is rigid fiberglass board or open cell acoustic foam (much more expensive) - both of these products absorb sound at a very good level across a variety of frequencies (the thicker the better).  Here's a link to find rigid fiberglass board and similar acoustic absorbents: http://www.atsacoustics.com/cat--Fiberglass-and-Mineral-Wool-Batts-and-Boards--106.html

Most road noise will be at least above 500Hz, probably with the most annoying stuff in the 1000-3000Hz range (about where the human voice resides so our ears are tuned to listen to that range).  Something to keep in mind if you're reading up on what types of materials you want to use (if you do, absorption co-efficients below 0.3 can be barely noticeable whereas above 0.6 are considered good, with above 1 being excellent).

Great, now my mind is thinking about how to best measure the effectiveness of all this.  <-recording device as I'm driving 

[Dazzler]

That post is definitely worth a thank you (good info there) 

[Phil №❶]

stochastic

Very interesting post. I don't have any technical qualifications, but 1 thing I do know, is if you take a hollow tube and fill it with expanding foam, significant vibration reductions occur. Because the foam is very tacky, all internal surfaces become glued to the foam and movement is considerably restricted. Unfortunately, the foam is of low density which does not assist noise reduction, but we can't have everything. With your greater knowledge than mine, maybe you can work out where and how to apply this stuff to be most effective.

When I drive, I feel that most of the noise is coming through the suspension struts and the roof of our car. 

[stochastic]

The rigid expanding foam has its strengths and weaknesses.  I do like how it creates a good seal for air (it's original intended purpose), and I also like how it bonds to the surface creating a second layer of differing density for the sound to travel through (somewhat dampening the surface).  The downside is its rigidity - by being so rigid it allows sound transfer much better than if the final foam still had some elasticity or give to it.  The rigidity also changes the resonance of the surface (most likely raises the resonant frequency).  This is about where I start to realize I'm not a physics major.  I'd need to take a look throughout the car (preferably with a decibel meter in hand) before I could really start advising as to the best regions for rigid foam application.  In most circumstances it should be stated that specialized audio products (automotive deadening mats, dampening pads, etc..) will give much better results than improvised home building materials (not all circumstances, but most).

[georgel]

Hi everyone! I'm new to this forum and a proud owner of a new i30. Coming from a Mondeo, I have noticed the noise in i30 cabin and was thinking about improving the sound insulation. I would like to know, before doing anything, if any modifications (like sticking soundproofing pads to the metal) or work (like removing the trim) will void the warranty?
If anyone knows how soundproofing may affect the warranty, please drop a line here.
Many thanks!

[Phil №❶]

Welcome georgel,

Thanks for joining, noise is an ongoing problem for this vehicle. I don't think that installing passive devices will void your warranty, as they sit still and don't affect anything else. If you intend to remove plastic panels etc to install these devices, then there could be issues regarding the clips that they use to fasten the panels. They only are meant to be installed once and sometimes break on opening. I would buy some spares and where necessary, replace any that break. 

[Dazzler]

Welcome Georgel

I agree with Phil.. Shouldn't be an issue...

There is a very recent thread on here about how to reduce road noise so I think I'll merge yours with that ...

[Shambles]

There is a very recent thread on here about how to reduce road noise so I think I'll merge yours with that ...

Buhahahaha. I'd just split it from that thread as it wasn't a "how to" but a "how do I"

[Dazzler]

 

[georgel]

Looking at the spare wheel well, I noticed that there aren't any dumping, just bare metal. I was thinking about having a "sound absorbing" mat underneath the carpet, so it covers the spare wheel well and the floor in the boot. And maybe stick some noise absorbing foam to the parcel shelf. Do you think this will make a difference in the noise level or it's a waste of time/money?

G

[Dazzler]

I think that should be worth doing 

[stochastic]

Looking at the spare wheel well, I noticed that there aren't any dumping, just bare metal. I was thinking about having a "sound absorbing" mat underneath the carpet, so it covers the spare wheel well and the floor in the boot. And maybe stick some noise absorbing foam to the parcel shelf. Do you think this will make a difference in the noise level or it's a waste of time/money?

G

That sounds like a logical and realistic approach to deadening the sound transfer from the boot.  I find most of the noise in my Touring tends to be engine noise rather than rear wheel noise.  Just make sure you're targeting the area where most of the noise is be noticeable.

[Phil №❶]

We have a product that is made to seal leaks in roofs. It is aluminium foil roll backed with a tar like substance. It is self sticking and would be perfect for your wheel arch, I'm going to do mine for sure.