Low frequency 'boom' in cabin

[cr_2dman]

6 hours ago, TonisT said:

Roof lining is normal. I had ford focus before and lining was very similar.

However  roofs metal is thin and has large area where there are no bends or supports so vibrates very easily. 

 

Other thing that was significant difference was suspension. I had "sports" suspension which was lower and stiffer. Went back to normal height and used ww golf dampers front and rear and lesjöfors springs rear. Rear springs made significant difference in boominess  while driving.

Unfortunately compared to my old 2006 ford focus this car has tendency to ring so to speak.

I did focus noise insulation also and it was much easier to get desired result because it was just loud noise  and it didn't ring.

Octavia has much more ringing to it and therefore I have to do doors again. I damped only inner surface of doors under the door cards. However front doors still ring when I shut them compared to rear doors because they are larger and the metal is very thin. So I need to do front doors again and also dampen the outer sheet metal.

One more thing I did and had noticeable difference is static vibration dampers on suspension parts. Those things work.

 

The Lesjofors are similar to the billstein B14 one's ?

Can you explain this 'ring' sound. Mine doesn't make this at all ?

 

 

[TonisT]

Like guitar for example pick a string and let it ring, so it plays long time. Keep yopur finger loosely on the string and pick it again, it makes just a "thud" and it won't stay ringing.

English is not my first language so I hope you understand what I mean.

Focus was more like keeping finger on the string. You had a noise but it would be silent right after the source was gone but octavia has more of a tendency to still keep"playing the note" for a period of time even after the source is gone silent.

About Bilstein B14

I do not know, never used Bilstein stuff. I used oem golf struts with springs in front (golf ones have much better ride quality than octavia stuff even tho they looked identical) and rear dampers were also golf oem ones. Just the rear springs were lesjöfors. Lesjöfors was just something that was easily available in my part of the world. Plus lesjöfors is very well known industrial spring manufacturer. I just picked known estate vin with normal suspension and got the springs.

Normal suspension spring vs sport suspension spring had definite ride quality difference twords comfort and also noise reduction.

I got my car used and it was imported from Germany. It had sports suspension from factory. However here in Estonia with lousy roads and real winter with plenty of snow, sports suspension made no sense.

Edited 11 April, 2019 by TonisT

[MC Bodge]

6 minutes ago, TonisT said:

Like guitar for example pick a string and let it ring, so it plays long time. Keep yopur finger loosely on the string and pick it again, it makes just a "thud" and it won't stay ringing.

English is not my first language so I hope you understand what I mean.

Focus was more like keeping finger on the string. You had a noise but it would be silent right after the source was gone but octavia has more of a tendency to still keep"playing the note" for a period of time even after the source is gone silent.

 

Yes, that is a good description. 

 

The Octavia (and seemingly other VAG cars of the same generation) has an undamped resonance that is in the audible range at various places in the body.

[TonisT]

Rear static dampers were just bolt on. No drilling needed. 

On front- ford damper that is on the strut - no car modifications needed. Modified the damper itself and used a thick washer underneath.

On front swingarm - needed to drill 2 holes per side to the swingarm. Need to be careful and make sure that wheel will not touch the damper when on full lock.

[MC Bodge]

Good info, thanks.

 

Having driven my car fully loaded with family, camping gear (including sleeping bags stuffed into the under boot floor space) and 3 bikes on a rear tailgate rack:

The car's ride was very good.

There was no booming noise and the whole car seemed quieter.

When driving about with the load and bikes removed, the chattering ride over rough tarmac returned.

On the way home, fully laden, the car was smooth and quiet again.

I need to try driving it empty, but with the bikes on the back to check if that stops the booming noise.

 

 

[MarkyG82]

I think I'll look at getting a couple of those BWM dampers.  Have bilstein B6 all round now and although it have made a difference it is still a bit boomy.  I tend to carry a fair bit a stuff under my false floor so that helps a bit also.

I may be moving to an area that has fewer speed bumps so will look into lowering spring then.  I think this will tighten it all up a bit and also provide better progressive action.

 

Edit: What do people think about adding these dampers to the sprung mass of the car?  I'm assuming the mass of the car is far to great for them to have any real affect.

Edited 7 May, 2019 by MarkyG82

[MC Bodge]

37 minutes ago, MarkyG82 said:

Edit: What do people think about adding these dampers to the sprung mass of the car?  I'm assuming the mass of the car is far to great for them to have any real affect.

I presume that you mean the unsprung mass?

 

The mass added compared with the sprung mass will be fairly insignicant, but it will have "some" effect. I doubt that it would be noticable to the driver.

 

 

[MarkyG82]

1 minute ago, MC Bodge said:

I presume that you mean the unsprung mass?

 

The mass added compared with the sprung mass will be fairly insignicant, but it will have "some" effect. I doubt that it would be noticable to the driver.

 

 

 

Yes sorry. As an engineer I should really get my definitions correct.

 

So, I'll leave sprung mass damping for now and just get 2 of the listed masses for the rear arm.

[MC Bodge]

It will be interesting to hear how it goes.

[TonisT]

I would think that going from 16 to 18 inch rims  which are both suitable to octavia, would be much greater weight difference than adding those bmw dampers.

I know it is subjective but to me they made a difference.

I have no way quantifying how much any on thing changed things but at the moment I have car that is relatively comfortable and quiet even on our lousy roads. I have full sound deadening that I did (interior out and everything) + dampers+ front deadset kit. +f1 asymmetric 3. Everything combined means that before it would hurt my ears to point I used earplugs and now  it's nice and comfy on the same roads. It was gradual improvement and not one single thing that I did.

However I did notice the dampers and roof was also a huge source of sound.

Dampers are good in that sense that they damp the vibrations where it matters, at the source. So for their relative small size they did noticeable difference to me.

Edited 7 May, 2019 by TonisT

[cr_2dman]

I've noticed the boom sound occurs after 2 seconds the ACT kicks in. It goes away when you keep the car in 4 cylinder engine.

(I've got the new 1.5 150PK TSI ACT engine)

 

Also, the boom sound is now a sound like you keep a window open while driving.

 

Edited 9 May, 2019 by cr_2dman

[MarkyG82]

I have finally got round to buying a pair of BMW mass dampers and also a pair of ford ones for the front struts.  Should be arriving some time this week so give me a week or so to fit an I'll report back.  

Should also say that I have now got Pro-Kit springs installed which has also helped.

[fabdavrav]

There is a VAG damper made for the rear multilink suspension..I fitted it to my MK7 Golf estate & did a "how to guide" here:-

 

https://www.golfmk7.com/forums/index.php?threads/how-to-retro-fit-the-rear-subframe-harmonic-damper-from-the-audi-a3-saloon-2013.369369/

 

[MarkyG82]

@fabdavrav thanks for the link.  If the parts I have are not enough (or wrong) then I will look at your solution.  Don't suppose you know the bolt spacing for the part?  The torsion beam axle has some holes along it but not the same as those on the IRS golf/vrs.

[fabdavrav]

2 minutes ago, MarkyG82 said:

@fabdavrav thanks for the link.  If the parts I have are not enough (or wrong) then I will look at your solution.  Don't suppose you know the bolt spacing for the part?  The torsion beam axle has some holes along it but not the same as those on the IRS golf/vrs.

 

Sorry, No I don't know the bolt spacing....bugger!

 

I've had a look on ETKA to see if a part was fitted to the beam rear axle for a different year/market, but can't find anything...bit strange there are bolts holes there....they will be for something!

[MarkyG82]

1 hour ago, fabdavrav said:

 

Sorry, No I don't know the bolt spacing....bugger!

 

I've had a look on ETKA to see if a part was fitted to the beam rear axle for a different year/market, but can't find anything...bit strange there are bolts holes there....they will be for something!

They are more like oval holes. A bit like you use for saving weight. 

[KenONeill]

48 minutes ago, MarkyG82 said:

They are more like oval holes. A bit like you use for saving weight. 

Funny, but accurate.

[fabdavrav]

1 hour ago, MarkyG82 said:

They are more like oval holes. A bit like you use for saving weight. 

 

Oh right..not bolt holes then..& those oval holes in the rear beam axle I had a look at on Google...it should fit between two of them...the solid part between them is short enough to fit between the bolts/studs on the Audi A3 damper I recon..

[MarkyG82]

2 hours ago, KenONeill said:

Funny, but accurate.

 

Weight saving on a torsion beam Octavia.....  🤣🤣🤣

 

1 hour ago, fabdavrav said:

 

Oh right..not bolt holes then..& those oval holes in the rear beam axle I had a look at on Google...it should fit between two of them...the solid part between them is short enough to fit between the bolts/studs on the Audi A3 damper I recon..

 

In one of the 'drive' links on a previous page it shows them mounting dampers using the holes so yeah, should be fine.

[MarkyG82]

Update:

 

Fitted the BMW 'blob' dampers this morning with 4 washers (6-8mm) underneath. Needed that many as the body of the 'blob' was catching on the torsion beam. Quick spin round the block suggests they really do make a difference. I'll give it a chance for the suspension to settle as I had it up at both ends and various points of the install.

Talking of the front end, I got a couple of the ford dampers that mount on the drop link tab on the front shocks. Modified them by lopping off the extra tab so they will sit flush. Good bit is you can get at the mounting point without removing the wheel. Just jack it up with the steering on full lock and you can get to it. Good idea to jack both sides at the same time to save putting stress on the bolt. Failure time was when I found my stock of washers had nothing big enough. At least M12 required maybe even 14. So I couldn't fit them this time round. I'll borrow some washers from work or something and have another go on my next day off. 

 

Summary:

Couldn't fit the front ones but the rears went in ok and make a difference.

If I can find a decent priced center mass for the rear beam I will go for it as if it's the same difference with each addon it'll be lovely with front, rear and rear-center.

[MC Bodge]

I conceded defeat. 

 

My Octavia has now gone after 10 months of frustrating ownership. Had it been a brand new car, it would have lasted me only two days. 

 

 

 

 

[ima]

Me as well. Such a shame as I loved it otherwise but couldn’t put up with the noise. 
 

Has this been resolved now if buying used?

Edited 16 August, 2020 by ima

[ima]

Sorry to bump this topic but I am ready to change my car and would 

I’ve to go back to the VRS. This time though I’m looking at a 2017 facelift and really need to know if the facelift still has problems with booming as it’s a no go if it does. I can’t see new posts on facelift so assume it’s been resolved but any knowledge greatly appreciated.

 

Thanks

[ima]

I’ve arranged a test drive but would still like to know if the new boot clips worked on the facelift.....anyone or is it topic fatigue on this 😀

[cr_2dman]

On 22/08/2020 at 11:48, ima said:

I’ve arranged a test drive but would still like to know if the new boot clips worked on the facelift.....anyone or is it topic fatigue on this 😀

 

i have the booming issue on my skoda octavia facelift mk3 , 1.5 tsi. It irritates me. My wife doesn't hear it (or doesn't care)

I've even driven the exact same car in a test center, it also had the boom.