What sound insulation is present on regular M3s but not the CSL?

[repoman89]

Curious if anyone has a decent list of what sound insulation BMW themselves thought was superfluous enough to eliminate in the CSL and that justified the weight savings. I’m guessing it doesn’t amount to much but would be worth it to keep in mind during various stages of tearing the car apart.

[NZ_M3]

The only one they kept on the CSL is by the pedal box. Otherwise there are none.

[heinzboehmer]

The only one they kept on the CSL is by the pedal box. Otherwise there are none.

Don't the CSLs still have insulation between the headliner and roof?

Edit: Also between the engine and firewall and in the transmission tunnel, no?

[NZ_M3]

Don't the CSLs still have insulation between the headliner and roof?

Edit: Also between the engine and firewall and in the transmission tunnel, no?

The ETK is notoriously inaccurate when it comes to the CSL. I can name quite a few errors off the top of my head.

I have personally had the headliner off my car and it does not have sound insulation.

You have to remember also that CSLs vary from production to production and even preproduction cars - there are actually two versions of the carbon roof for example made differently which some early cars got and there are at least 5 versions of the front splitter, 3 versions of the centre console at least 2 to 3 versions of the door card and the list goes on. I really should document some of these differences.

I need to double check the front engine bay one but I also recall that one is non existent. The transmission tunnel one - are you referring to the black thin material one or the thick foam ones? Or the heatshield?

The rear door cards also don’t have the foam backing and it’s also missing a metal cover on the chassis that you find on stock M3s.

But basically apart from the one by the pedals and the thin foam one behind the door cover there’s no sound deadening.

[heinzboehmer]

I have personally had the headliner off my car and it does not have sound insulation.

Very cool, more weight reduction potential. Always assumed that was there on CSLs.

I need to double check the front engine bay one but I also recall that one is non existent. The transmission tunnel one - are you referring to the black thin material one or the thick foam ones? Or the heatshield?

I'm referring to the black thin-ish (maybe 10mm thick?) One that goes between the transmission and the transmission tunnel.

I really should document some of these differences.

You should! Really appreciate the info. I've come to trust your posts more than the ETK because I've realized how inconsistent/inaccurate it can be.

The reason why I mentioned those three things is because I've recently been trying to figure out what insulation BMW left out on the CSL. I want to start shedding weight off of my car and figured that ripping out anything BMW deemed unnecessary for the CSL was a great way to start. However, I drew these conclusions from looking at pictures and videos online (because, once again, I've stopped blindly trusting the ETK). Happy to be proven wrong on these three things, since it only means there's more weight loss potential.

[Slideways]

Very cool, more weight reduction potential. Always assumed that was there on CSLs.



I'm referring to the black thin-ish (maybe 10mm thick?) One that goes between the transmission and the transmission tunnel.



You should! Really appreciate the info. I've come to trust your posts more than the ETK because I've realized how inconsistent/inaccurate it can be.

The reason why I mentioned those three things is because I've recently been trying to figure out what insulation BMW left out on the CSL. I want to start shedding weight off of my car and figured that ripping out anything BMW deemed unnecessary for the CSL was a great way to start. However, I drew these conclusions from looking at pictures and videos online (because, once again, I've stopped blindly trusting the ETK). Happy to be proven wrong on these three things, since it only means there's more weight loss potential.

Did you watch the Redish CSL restoration video?

[Sharocks]

I don't actually know what the sound deadening differences are but I will say this, I got a ride in a local E46 M3 with all the standard mods but with an OE CSL airbox. Could barely hear it.

Went to Istanbul and got a ride in two different CSL's, each with exhausts, suspension and various changes but otherwise nothing crazy, and holy shit it's loud as all hell on the inside.

If anyone figures it out, please share.

[NZ_M3]

I'm referring to the black thin-ish (maybe 10mm thick?) One that goes between the transmission and the transmission tunnel.

do you mean on the exterior? If so then yes those are there. I have a feeling the one behind the dash is there also but I need to check again. From my photo archive one of the photo shows it missing but it might have been removed for photographing purposes.

The roof one is definitely not there. I took my roof liner out when I saw people posting them installing the insulation for carbon roof install and I thought that was weird as I distinctively recalled there were none when I did the job years ago.

[NZ_M3]

I don't actually know what the sound deadening differences are but I will say this, I got a ride in a local E46 M3 with all the standard mods but with an OE CSL airbox. Could barely hear it.

Went to Istanbul and got a ride in two different CSL's, each with exhausts, suspension and various changes but otherwise nothing crazy, and holy shit it's loud as all hell on the inside.

If anyone figures it out, please share.

Flap or no flap control?

[heinzboehmer]

do you mean on the exterior? If so then yes those are there. I have a feeling the one behind the dash is there also but I need to check again. From my photo archive one of the photo shows it missing but it might have been removed for photographing purposes.

Yeah on the bottom of the car. Here's the best image I could find of it with a quick search:

[heinzboehmer]

Did you watch the Redish CSL restoration video?

Yup that video made up a big chunk of my research lol

[Sharocks]

Flap or no flap control?

Both had functional flaps.

[repoman89]

I don't actually know what the sound deadening differences are but I will say this, I got a ride in a local E46 M3 with all the standard mods but with an OE CSL airbox. Could barely hear it.

Went to Istanbul and got a ride in two different CSL's, each with exhausts, suspension and various changes but otherwise nothing crazy, and holy shit it's loud as all hell on the inside.

If anyone figures it out, please share.

I’d be curious to have you ride in my car one of these days. I’d describe it as loud as all hell inside, but maybe I’m just soft 😂

I will say I screwed up the flap wiring at first so it was stuck closed and it was obviously underwhelming. It had the character I expected based on videos but similar volume to stock. I fixed it and now have it programmed to be always open in sport mode and that’s the only way I drive it, so the flap was essentially a waste of a lot of effort.

It doesn’t seem particularly loud outside the car though with the hood closed. With it open it’s deafening. Need to get rid of that 0.5 ounce hood insulation lol.

Good info in this thread so far and good to know I can skip insulation when I do my roof.

[usdmej]

You have to remember also that CSLs vary from production to production and even preproduction cars - there are actually two versions of the carbon roof for example made differently which some early cars got and there are at least 5 versions of the front splitter, 3 versions of the centre console at least 2 to 3 versions of the door card and the list goes on. I really should document some of these differences.

i would be very interested in learning those differences!

only thing i heard about production differences was that BMW took a stab at producing the CSL airbox in house for a hot minute before reverting back to the original CMO

[S14]

It doesn’t seem particularly loud outside the car though with the hood closed.

I hung around the Nurburgring a lot back when the CSL was a common track toy. You could hear that induction noise miles away! Only the E30 M3's with carbon airboxes had louder, more distinct and pleasing intake roar.