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Model specific boards => Golf mk7 => Topic started by: mcmaddy on 25 May 2024, 17:57

Title: Under bonnet sound deadining
Post by: mcmaddy on 25 May 2024, 17:57
The under bonnet sound deadining has shrunk again on my TCR. It'll be replaced under warranty when my car goes in for its service in July. Has anyone just removed the deadining? What's the downside if any to removing it?
Title: Re: Under bonnet sound deadining
Post by: P6GTD on 25 May 2024, 20:19
Cooking the bonnet paint?
It’s a heat shield , not sound deadening as I understand it.
I had it replaced 3 times in 3 years under warranty.
Latest one in 2 years in and ok.
Title: Re: Under bonnet sound deadining
Post by: mcmaddy on 25 May 2024, 21:11
If it's a heat shield why did the Clubsport S not have one fitted? I did think about the bonnet paint but plenty of other vag group cars don't have it fitted. Would a turbo blanket stop the heat?
Title: Re: Under bonnet sound deadining
Post by: P6GTD on 25 May 2024, 21:17
All great points McMaddy.  I only called it a heat shield as that’s what my dealer called it.
Title: Re: Under bonnet sound deadining
Post by: willni on 25 May 2024, 21:45
Its primary purpose is a heat shield with sound deadening secondary. Any rear engined cars typically don't have these on the bonnet. The heat can cause paint fade or cracking to the acrylic lacquer over time.

In terms of the CSS, it's very much a function first car. Sound deadening across the car is heavy and often low down, so if you can remove 3kg removing unnecessary items then it helps track times.

If you do proceed with removing it completely, I'd fit heat reflective tape in its place. Also note if you have PPF on the bonnet I definitely wouldn't remove it, as over time it will heat the glue and crack the film and be a nightmare to remove / repair.
Title: Re: Under bonnet sound deadining
Post by: mcmaddy on 25 May 2024, 23:40
Why can't VW just provide one that doesn't shrink 😂
Title: Re: Under bonnet sound deadining
Post by: EB2019 on 26 May 2024, 09:26
I looked into this recently and had my own queries about it.
I don't think isn't actually a heat shield despite what the dealer guy called it, and its not called that in the VW parts catalogue system (I have access to this for work). I think its called a sound absorber, and as mentioned the Clubsport S didn't have the sound absorber (its like paper and weighs about 300g when I took mine off).

Other vehicles on the similar platforms within VAG with vastly more power don't have these fitted as the pad retains heat under the bonnet, Audi RS3 and TTRS just 2 examples. The under bonnet temps on a 400bhp + RS3 must be way higher than the Golf. They are likely not fitted as the metal bonnet is very good at heat dissipation, as heat wants to radiate to the coolest point in all directions making it good at mitigating temp. 

IMO VW didn't need to fit them as they don't do the primary job either of reducing meaningful noise, and would have saved endless warranty replacements.  Mine has been off for months and the bonnet isn't really hotter on the long round back from Europe and the cabin isn't noisier (tyres being the primary noise at speed).  The metal on the fire wall behind the turbo appears to be for heat and has similar sound absorber behind it, and that is the correct product in that location. You could assume If VW wanted to put that on the bonnet to reduce heat they could have done, but chose to fit a sound absorber for mostly idle speed mechanical noise reduction it seems.
Title: Re: Under bonnet sound deadining
Post by: Finglonga on 26 May 2024, 11:22
Not a heat shield in any way as many cars never have it fitted. It is sound deadening and tries to hide the ticking sounds, rattles etc in the higher frequencies. Dynamat do an under bonnet kit that will work better than the OEM one.
Title: Re: Under bonnet sound deadining
Post by: joe6 on 28 May 2024, 15:43
Had this replaced under warranty on my 2019 7.5 and was told it would not last by the dealership. 20k miles later and it is still fine. Material seems slightly different from the original.
Title: Re: Under bonnet sound deadining
Post by: P6GTD on 28 May 2024, 18:21
Yes, my final one remains good. I think it was about the lugs that didn’t fit far enough into the slots on the bonnet underside allowing them to sag.
Title: Re: Under bonnet sound deadining
Post by: Rudedog on 29 May 2024, 12:04
My replacement was ok up until about 4 months ago - as has been said it's just the two tabs nearest the washers that have become ever so slightly too short so pop out - just need to think of some material I can maybe stick to the back to extend the tab by about 20mm so it stays in place.

Title: Re: Under bonnet sound deadining
Post by: coolhandluke123 on 29 May 2024, 13:09
My replacement was ok up until about 4 months ago - as has been said it's just the two tabs nearest the washers that have become ever so slightly too short so pop out - just need to think of some material I can maybe stick to the back to extend the tab by about 20mm so it stays in place.

Report back if you come up with a solution, I can't seem to find anything that wants to stick to the existing material.
Bur agree that just making a couple of the lugs longer should solve the problem.
Title: Re: Under bonnet sound deadining
Post by: willni on 29 May 2024, 17:09
Bit of welding wire or a coat hanger stuck through it and wrap it in heat tape to prevent knocking.
Title: Re: Under bonnet sound deadining
Post by: Rudedog on 16 June 2024, 17:44
This is the route I ended up going down - very simple and blatantly taken from another VW thread I read when doing some further reading.


(https://i.postimg.cc/L8dqwjMg/temp-Imagec-WZo-Ky.avif) (https://postimg.cc/4m5Nh7yX)

(https://i.postimg.cc/gkLXgN1P/temp-Imagei-Xt-Cz-U.avif) (https://postimg.cc/rKcwmC8h)

I had a few wide cable ties which rather than cut I just tucked in the next bonnet gap - stupidly simple and it now sits nice and flat.
Title: Re: Under bonnet sound deadining
Post by: madstaff on 16 June 2024, 19:29
^^^
Did a similar thing but i used velcro straps.  :smiley:
Title: Re: Under bonnet sound deadining
Post by: coolhandluke123 on 18 June 2024, 10:27
Just did the cable tie suggestion and it's done the trick , many thanks for the suggestion 👍
Title: Re: Under bonnet sound deadining
Post by: mcmaddy on 18 June 2024, 10:51
Mines way too far gone to velcro or cable tie  :sad:
Title: Re: Under bonnet sound deadining
Post by: P6GTD on 18 June 2024, 17:12
I idly wonder if the material spec was changed to be more resistant to under bonnet heat?
My first two were replaced under warranty.
The third also under warranty has been perfect with no mods.
Title: Re: Under bonnet sound deadining
Post by: mcmaddy on 16 July 2024, 11:49
Garage refused to replace mine under warranty yesterday 🤬
Title: Re: Under bonnet sound deadining
Post by: Watts on 16 July 2024, 18:23
Garage refused to replace mine under warranty yesterday 🤬

Is that because you have an all in one plan warranty or were they playing difficult with an extended from new warranty?
Title: Re: Under bonnet sound deadining
Post by: mcmaddy on 16 July 2024, 19:42
Garage refused to replace mine under warranty yesterday 🤬

Is that because you have an all in one plan warranty or were they playing difficult with an extended from new warranty?
It's just an extended warranty after the standard 3 year one ran out. Disappointing but expected the not covered chat.