Under bonnet sound deadining

[mcmaddy]

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?

[P6GTD]

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.

[mcmaddy]

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?

[P6GTD]

All great points McMaddy.  I only called it a heat shield as that’s what my dealer called it.

[willni]

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.

[mcmaddy]

Why can't VW just provide one that doesn't shrink 😂

[EB2019]

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.

[Finglonga]

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.