C5X soundproofing

[PaulC5]

A bit of noise in a car is useful so you can not hear the co pilot.

Tyres seem to generate quite a lot of noise so it is worth checking the noise levels when buying replacements and newer ones seem to be louder than worn ones. Different road surfaces give different noise levels, concrete and higher grip surfaces being bad so when doing any comparison measurements it ought to be done on the same stretch of road.

In the 1980s I once sound proofed a car using one of those sticky felt mat kits which mostly went under the carpets, over the wheel arches and under the bonnet. Plastic wheel arch liners did not exist then. It might have helped but I can not remember and never did another car.

[DS9]

I dislike headphones in general and surprised at how many people I see driving with them in, it's dangerous. One thing noise cancelling are handy for though is flights, makes it far more relaxing.

If I took my door cards off I'd have put a bit of deadening in even if it was only a few patches. The C5x doors sound like they have nothing in them. dB noted!

I think the whole sound deadening thing has been lost on people. Yrs ago they said the difference between a VW and an Audi was 50kg of sound deadening, might be the same now, dunno. But in the world where everyone is trying to improve emissions regs it's an easy thing to cull.

Thing is too is up to about 2dB people apparently can't tell is different, so you need to try and get more than that. Hopefully I do. The last wheel well should add a bit more and then there's the boot floor. This must cover about a quarter if not a third of the cabin and there is nothing there to quieten it above or below. At the most simple level maybe 1sqm of deadening, weighing circa on kg and costing a tenner or a bit more and half an hour's labour may improve it by a dB, it's an easy quick win for anybody.

Tyres are something I've pondered. I'd change mine if I could get an offer on the ones I have. Efficientgrip with under 2k miles on them, still look like new. Anyone feel free to make me an offer.

One final thing is wheel balancing, I noticed when I took mine off they have very small almost 1 token weight on every wheel, so are they balanced well? I'll find out tomorrow when I take it into Kwik Fit. They are checking them all, £8.20 each.

[mickthemaverick]

What size are the tyres?

[DS9]

205/55/19, V rated. C5x standard fare. Most if not all seem to have them factory fitted.

[mickthemaverick]

Too big for me, However in the interest of noise reduction and you are thinking of changing them anyway I'd suggest you consider swapping to 18" wheels with 205/65/18 tyres to give you more sidewall, better cushioning and cheaper tyres!

[myglaren]

I dislike headphones in general and surprised at how many people I see driving with them in, it's dangerous.

That was not a serious suggestion and I believe that it is illegal to drive with headphones on precisely as it cuts out important audible information. The sirens of the police car behind you as one instance.

[DS9]

I look on here normally, https://tiresize.com/comparison/

Sorry, I think they may be 215's cant remember.

I might be able to go up from 55s to 60s, would give me close to 10% extra sidewall which would be handy but thats as far as I'd go. It'd be a pfaff changing the alloys too.

In general I'd just like quieter tyres, I'd be happy with that.

[PaulC5]

A search suggests your existing tyres (using 205) have a low noise level at 69 dB so no benefit in changing them. Other makes are 70 to 71.

[DS9]

Thanks for that. I'm sure I saw somewhere they were 71, how wrong I was. Just checked on Asda.

They are 205s.

I thought of the Pirelli Powergy at 68 but it's not worth the hassle for a drop of one. For 3 I'd do it.

[DS9]

While I've been waiting for my extra supplies to arrive I've found a few solutions and added a few more problem places.

1) I don't want to sound deaden the boot over the battery as in case of warranty claim they may say it was a contributory factor....overheating. We have an old low density rug which is a great size so I've put that over the top and tucked it in well behind the back seats.

2) The plastic wheelarches have a little flap at the bottom in front of the tyres, tap these and they rattle horribly on the rears, less so on the front's. The sound deadening I've done sorts that.

3) Those panels around the 12v socket in the boot sound horrible on the tap test. I know I can get in behind and sort them but unsure if I can actually get in above the rear wheelarches.

4) While the plastic sills on the bottom of the doors which meet an underbody seal are a great idea for keeping the car sills clean they do fail the tap test. I played around yesterday a little and whether its a 5mm or 10mm layer on top doesnt make much difference, it just deforms the seal a little more. With the doors closed if you tap these plastic "sill guards" they still rattle when adjoined to the seal. I'm going to think about this a bit but does need a few mm of something on there just to make it sound less tinny. It needs to be smooth too as rubber on rubber wouldnt be good imo. Unlike most of my efforts it also needs to look good as well.

Why I think this is a problem is the doors seem to have no sound deadening in them and I think the noise rises from these plastic "sill guards" up through the doors.

[MattBLancs]

I have to say I have never known anyone, in 55 years of motoring, put so much effort into sound deadening. In fact I don't recall anyone putting any effort in at all!!

You'd be surprised Mick, there's some folks very keen on it! I've read up on it a bit in the past.
Dynamat, etc products are quite expensive and all about "mass loading" panels.

(I've also read self adhesive flashing tape is the cheapskate alternative!)

Examples of what commercial ventures can do (just a quick Google search)

https://www.advanced-incar.co.uk/produc ... age-1-2-3/

[mickthemaverick]

You'd be surprised Mick, there's some folks very keen on it! I've read up on it a bit in the past.
Dynamat, etc products are quite expensive and all about "mass loading" panels.

Not really surprised, no doubt it was born during the need to turn the car into a mobile disco, long after my mad days when we used to turn a lowly saloon into a potent rally car when it was all about taking out anything we didn't need for lightness!! All about driving for us, left the dancing to the proper disco!!

[MattBLancs]

Can see various sides to "car modification" - there's a group minded to make cars lighter, faster, stop and go better (and Colin Chapman's "add lightness" mantra kicks in with luxurious sound proofing seen as unnecessary dead weight)

There's automotive audiophiles who want the minimum background noise and maximum (usually quality but sometimes quantity) output from the car's audio.

There's a group who just want the most serene effortless transport possible (and the hydropneumatic Citroens cover aspects of that like nowt else!)

There's even Ecomodders who'll seek to optimise their vehicle in pursuit of maximum fuel economy (and driving style - sometimes borderline dangerously: tyres at 60psi tailgating lorries isn't sensible to me!)

Oh, and there those obsessed with bloody "stance", "lows" and stretched sidewalls who are making a car literally terrible at being a car, in pursuit of that particular visual style.

I've time for aspects of all but the latter!

[Sloppysod]

Too big for me, However in the interest of noise reduction and you are thinking of changing them anyway I'd suggest you consider swapping to 18" wheels with 205/65/18 tyres to give you more sidewall, better cushioning and cheaper tyres!

According to my research, either standard 19" or 17" wheels have been approved for the C5X in the UK.

[DS9]

Too big for me, However in the interest of noise reduction and you are thinking of changing them anyway I'd suggest you consider swapping to 18" wheels with 205/65/18 tyres to give you more sidewall, better cushioning and cheaper tyres!

According to my research, either standard 19" or 17" wheels have been approved for the C5X in the UK.

I read once somewhere that the 19 inchers were only going to be for the UK because of our love for large alloys and other places would get the 17s. That said I can't find a picture anywhere of one on 17s.

The 17s are a decent price, the 19s cost about 50% more. https://citroen-shop.eu/gb/470-wheels?o ... loy+wheels

I'm convinced it'd rise even better but not sure how it'd look though. The 19s do look quite nice even if I've discovered they do have plastic inserts.