How to retro-fit the rear subframe harmonic damper from the Audi A3 Saloon (2013->)

[fuelboss]

I think owners have to understand their are two issues. One is the shock absorber or so-called "rolling log" noise which is distinctly a tapping, knocking sound that only shows up over certain rough surfaces such as going over the edge of a pothole, going over a speed hump or ruts or ridges, backing into your drive for example, where the rear wheels suddenly hit the edge of the kerb resulting in a quick reaction on the shock absorber as the piston rod moves quickly in the barrel. Anything that created a rapid movement in the shock absorber could create that rattle even at 1 mph and that was the rolling log sound. This noise was not a constant. Anyone who replaced their shock absorbers with the likes of Bilstein should have eliminated that knocking sound as I did on my 2014 GTI after VW unsuccessfully replaced the Sachs shock absorbers 4 times along with top mounts. I have to say that if changing the shock absorbers to anything other than original parts was not the solution then this hollow knocking/tapping noise was not what the owner was trying to eliminate, and therefore that had to be something else!

That knocking noise from the shock absorbers as I have described was not a constant but if you had exactly that issue and changed the shock absorber to anything but an original part the knocking/tapping noise or however it is described it will be eliminated, but it will do little if anything for any resonance, continuous rumbling noise issues and that may well only be reduced by the fitting of this "balance weight". The notion that the "rolling log" sound would reappear after bedding-in is in my view not valid as I changed to Bilstein in 2015, and the vehicle was driven widely in Europe and the UK over a wide variety of surfaces and rough tracks and the noise was never heard again. I purchased a MK7.5 GTI last year 2018 and that knocking sound was immediately apparent on that vehicle. Not as bad as the MK7 but none the less it was audible. Changing immediately to Koni Actives and the noise has once again been eliminated completely.

To sum up if anyone has intermittent or irregular knocking sounds then change the shock absorbers. If it is anything other than that, if its a constant resonance/rumbling sound then don't bother with the shock absorbers but just try the "balance weight" . If I could fit that part now I would and the give you my views but unfortunately I cant fit until next year.

I hope that David is right in his view that the balance weight will quieten the vehicle but I cant see how it will cure an issue with the shock absorbers knocking or tapping sound that without doubt originates directly from the VW Sachs shock absorber. Just see my video from 2015 and you will see that its clear the shock absorber is the cause of the rattle

. I actually still have my originals and I can actually laterally move by hand the piston rods in the barrel to feel the excessive play that you do not get with either Bilstein or the Konis. I offered to show these to VWUK but naturally they were disinterested as of course they knew what was the issue at that time. My advice to anyone purchasing a MK7 or 7.5 GTI is find one with DCC.

It would be good to see more evidence that the "balance weight" will at least do something for the resonance but so far searching the web has brought about little information that fitting the device would be beneficial, though based on David's post it does look positive.

 

[Navi]

That's what I was going to say.

 

[anotero]

This is all very interesting.
I hit a resonance frequency when braking under certain circumstances, which manifests itself in a very audible hum/buzzing sound all around the car. I wonder if this damper will help alleviate that.

 

[golfdave]

I think owners have to understand their are two issues. One is the shock absorber or so-called "rolling log" noise which is distinctly a tapping, knocking sound that only shows up over certain rough surfaces such as going over the edge of a pothole, going over a speed hump or ruts or ridges, backing into your drive for example, where the rear wheels suddenly hit the edge of the kerb resulting in a quick reaction on the shock absorber as the piston rod moves quickly in the barrel. Anything that created a rapid movement in the shock absorber could create that rattle even at 1 mph and that was the rolling log sound. This noise was not a constant. Anyone who replaced their shock absorbers with the likes of Bilstein should have eliminated that knocking sound as I did on my 2014 GTI after VW unsuccessfully replaced the Sachs shock absorbers 4 times along with top mounts. I have to say that if changing the shock absorbers to anything other than original parts was not the solution then this hollow knocking/tapping noise was not what the owner was trying to eliminate, and therefore that had to be something else!

That knocking noise from the shock absorbers as I have described was not a constant but if you had exactly that issue and changed the shock absorber to anything but an original part the knocking/tapping noise or however it is described it will be eliminated, but it will do little if anything for any resonance, continuous rumbling noise issues and that may well only be reduced by the fitting of this "balance weight". The notion that the "rolling log" sound would reappear after bedding-in is in my view not valid as I changed to Bilstein in 2015, and the vehicle was driven widely in Europe and the UK over a wide variety of surfaces and rough tracks and the noise was never heard again. I purchased a MK7.5 GTI last year 2018 and that knocking sound was immediately apparent on that vehicle. Not as bad as the MK7 but none the less it was audible. Changing immediately to Koni Actives and the noise has once again been eliminated completely.

To sum up if anyone has intermittent or irregular knocking sounds then change the shock absorbers. If it is anything other than that, if its a constant resonance/rumbling sound then don't bother with the shock absorbers but just try the "balance weight" . If I could fit that part now I would and the give you my views but unfortunately I cant fit until next year.

I hope that David is right in his view that the balance weight will quieten the vehicle but I cant see how it will cure an issue with the shock absorbers knocking or tapping sound that without doubt originates directly from the VW Sachs shock absorber. Just see my video from 2015 and you will see that its clear the shock absorber is the cause of the rattle

. I actually still have my originals and I can actually laterally move by hand the piston rods in the barrel to feel the excessive play that you do not get with either Bilstein or the Konis. I offered to show these to VWUK but naturally they were disinterested as of course they knew what was the issue at that time. My advice to anyone purchasing a MK7 or 7.5 GTI is find one with DCC.

It would be good to see more evidence that the "balance weight" will at least do something for the resonance but so far searching the web has brought about little information that fitting the device would be beneficial, though based on David's post it does look positive.

Again, just trying to point out other peoples experiences & mine which are different to yours...

I have had those same noises which you attribute to a faulty factory Sachs shock absorber (in your case) & the other general noises...in my case the original factory Sachs dampers have passed 3 MOTs....& me inspecting them even as you show in the video, & all ok, no faults in my opinion.

Hypothetically, if I change the dampers it might be more quiet, but this part has reduced the noise by 3/4 from the rear of the car in my case, & the car is extremely quiet now!

Also I linked to another poster who clearly stated that the noise came back after 2,000miles on new Bilstein B4's...therefore new dampers did not solve it in his case!

Also someone posted a comment under one of your videos about this on youtube & they stated:- "my golf 7r with dcc has the same rear noise... changed the top mounts... it's gone only for few days...no solution at the moment from my dealer that knows the problem really well"..Also another post under another of your videos:- "Hi Rich, I am having a similar problem and i am thinking of changing the shock absorber with Bilstein, my car is Golf 7 GTD DCC 2013,"

So new top mounts & DCC doesn't solve it either!...& even the "R" which has a different subframe can have the sound!

It may not be the dampers at fault 100%, but tolerance issues between the damper rod & the top mount, as the top mount is designed to allow the damper rod to move around to reduce NVH.

The sound can either travel down through the damper & into the wishbone & get amplified via the rear subframe..this is where the balance weight stops this noise dead on the 2WD rear subframe. Or the sound can go directly into the bodywork via the top mount. However the connection between the top mount & damper rod acts like a spike under a floor mounted hi-fi speaker so limits the amount of sound transmitted into the bodyshell. Therefore what little sound I now have could be from this source/route, having stopped the amplified sound via the rear subframe.

Fitting a part which costs circa £60 & involves jacking the rear of the car up, placing item in situ & tightening two nuts is far cheaper & quicker than removing & fitting two dampers, which may not solve the problem!

 

[golfdave]

I hit a resonance frequency when braking under certain circumstances, which manifests itself in a very audible hum/buzzing sound all around the car. I wonder if this damper will help alleviate that.

Doubt it...totally different source of noise...(brakes instead of suspension)...Audi TT-S MQB 4 pot calipers have "balance weights" on them to tune out vibration.

 

[anotero]

Doubt it...totally different source of noise...(brakes instead of suspension)...Audi TT-S MQB 4 pot calipers have "balance weights" on them to tune out vibration.

I had this vibration with non-PP brakes, then with PP brakes. I know it's not the rotors. A very mysterious phenomenon.

 

[fuelboss]

I see that Golf Dave has found good improvements by fitting this balance weight/damper and that can only be good news. As I mentioned previously I am not with my car until March next year and therefore I cannot fit this item to make a comment on its effect. I am hoping that there will be more of you out there who will fit the part and then give your opinions.

Regarding the owner of a Golf GTD with DCC having the "rolling log" noise - well this was I believe the only person with DCC to report this after receiving hundreds of emails and messages from owners worldwide with non-DCC vehicles who definitely had the shock absorber issues. As far as anyone fitting the Bilsteins and not benefiting or finding that the noise returned, well I can only conclude that they had a totally different problem and not the same one associated with the Sachs shock absorber. The Sachs shock absorber was a real problem and this was recognised and acknowledged by VW in 2014. They never officially accepted it as as a fault for obvious reasons and simply referred to it as a "characteristic of the model"

 

[golfdave]

I see that Golf Dave has found good improvements by fitting this balance weight/damper and that can only be good news. As I mentioned previously I am not with my car until March next year and therefore I cannot fit this item to make a comment on its effect. I am hoping that there will be more of you out there who will fit the part and then give your opinions.

Regarding the owner of a Golf GTD with DCC having the "rolling log" noise - well this was I believe the only person with DCC to report this after receiving hundreds of emails and messages from owners worldwide with non-DCC vehicles who definitely had the shock absorber issues. As far as anyone fitting the Bilsteins and not benefiting or finding that the noise returned, well I can only conclude that they had a totally different problem and not the same one associated with the Sachs shock absorber. The Sachs shock absorber was a real problem and this was recognised and acknowledged by VW in 2014. They never officially accepted it as as a fault for obvious reasons and simply referred to it as a "characteristic of the model"

I think we can ALL agree that there are several possible sources for the noises that are created by the rear multilink suspension, whether 2WD, AWD, DCC, Bilstein, Sachs, etc.

Some noise is created by the inherent resonance flaws within the rear suspension, some is created by "faulty" Sachs factory dampers, some is created by the tolerance issue between damper rod passing into the damper top mounts, & some will be "a characteristic of the car" (see first fault)

You can either fit the "Harmonic damper/balance weight" which is designed to remove the first issue, or fit a different brand of dampers to fix the second issue, or buy a different brand of car....

Me?... I'd personnally chose the cheapest & easiest fix first...

 

[ZERO815]

Installed my „Gewicht“ yesterday. First impression from short driving around town is positive. On cobblestone roads, potholes, tarmac patch work the rear feels more solid now. It doesn‘t remove the impacts but the rear of the vehicle reacts less hollow, “cheap“ afterwards.

Installation took less time than opening my pit ?

 

[golfdave]

Installed my „Gewicht“ yesterday. First impression from short driving around town is positive. On cobblestone roads, potholes, tarmac patch work the rear feels more solid now. It doesn‘t remove the impacts but the rear of the vehicle reacts less hollow, “cheap“ afterwards.

Installation took less time than opening my pit ?

Glad it has some noticeable difference even on a "hatch" which has less bodywork than the estate.

You have a pit?..lucky you...!!!.....& yes its doesn't much time to install the item!

 

[ZERO815]

You have a pit?..lucky you...!!!

Can you imagine? The concrete guys left a hole for the stairs to the basement in the middle of my garage!

 

[George Ab]

Mine arrived in the US one month to the day after ordering from e-acca. Easy install. The car was quite quiet as I added noise insulation material and have Koni sport dampers and DWS tires. I will report back on driving impressions. I expect this to be a fix for noise under a specific circumstance not rolling constant noise.

 

[fuelboss]

View attachment 161413
Installed my „Gewicht“ yesterday. First impression from short driving around town is positive. On cobblestone roads, potholes, tarmac patch work the rear feels more solid now. It doesn‘t remove the impacts but the rear of the vehicle reacts less hollow, “cheap“ afterwards.

Installation took less time than opening my pit ?

Since fitting the damper have you any further views on its benefits and whether it is worthwhile fitting.

 

[fuelboss]

Just for added CLARITY.

I have the original factory Sachs dampers & they have passed 3 MOTs & even I can't find any problems with them & yet I had the "log rolling/hollow noise", therefore you can have perfect Sachs dampers but still have the noise.

Also swapping to the Bilstein B4s DOES NOT automatically guarantee eradication of said noise.
Quote from this forum:-



https://www.golfmk7.com/forums/inde...r-suspension-again.330995/page-5#post-6840547

The main thing YOU should be thinking about is why did VAG design a Harmonic damper for the MK5 Golf rear multilink suspension (2WD),...There is a KNOWN harmonic resonance in the subframe/suspension design!!!

They ask yourself why did VAG give it a MK5 Golf part number, & then produce all the MK6 & MK7 Golf (& all other car variants eg Octavia/A3) rear subframes with the two mounting holes??…...Yet they only released the part on the current MQB Audi A3 saloon?? All to do with perceived quality...that car (A3) is up against BMW etc....so has to be as quiet as possible the other cars were "acceptable for NVH" according to VAG.

Regardless of you having faulty dampers, there is an inherent resonance in the rear suspension which I am 90% certain is created by the lower wishbones (due to the extreme angles of interaction & arc travel from the damper to top mount)....the Subframe "amplifies" this noise through the bodyshell.....By fitting the harmonic damper to the subframe at the intersection between the lower wishbones this stops the resonance dead in its tracks before it gets a chance to travel into the rear subframe/bodyshell...

Golf Dave, have you an update on your opinions and benefits of having fitted this damper. Is it worth the effort. Unfortunately as yet, no one else appears to have made any comments, positive or negative on fitting this part.

 

[golfdave]

Golf Dave, have you an update on your opinions and benefits of having fitted this damper. Is it worth the effort. Unfortunately as yet, no one else appears to have made any comments, positive or negative on fitting this part.

I can add nothing further that what I have previously stated......Total silence from the rear of my car...& I've done numerous trips on the same roads/speeds that would previously make a noise....

On hard impacts/potholes the car will make a noise..but what do you expect...just the noise is less & more appropriate to impact