MLV / CCF Best Practices Trunk and Rear Quarters

[JWebb_C7_Comp]

Hey guys,

I've got the majority of my constraint dampening layer in the rear of my 2018 A6. In fact, I just need to add some to the rear deck as the sub-woofer/brace are going in and likely to the underside of the trunk lid, just to minimize the likelihood it will resonate. That said, the MLV, CCF, cement, and velcro have been ordered and I hope they'll be shipped Monday. So, I'll be on to step 2 next weekend or shortly thereafter.

When doing CCF/MLV on the floor of the A6/S6, has anyone used velcro on the back of the carpet to adhere CCF (facing down toward the metal) /MLV (facing up toward the underside of the carpeted pull out section? I figured doing that makes for a couple really easy reqtangular sections. I would separately use velcro to adhere a 2-3" strip along the edges such that when the carpeted cover is in place, the MLV there overlaps just slightly with that I'd place on the edges. Does that make sense or am I making this too simple and missing something?

For the sides, it almost seems as though I should be looking at "hanging" most of the MLV from velcro at the highest point I can reach on each quarter panel in sections that are as wide as possible. Then, once everything is in place, I'd glue vertical strips between the sections, such that most of them are not only overlapping, but connected. Clearly, there will be a few spots where I can't glue everything together because I wouldn't be able to remove the material later to access amps, wiring, etc.. If anyone has got a tried to true method for covering nearly 100% of the quarter/trunk area of our cars, I'd appreciate advice.

I've also got 4 SqFt of HMF that I plan to strategically deploy between wheel arch and speaker deck/rear seat backs to further reduce noise coming up from the tires/rear wheels.

Any advice/comments would be appreciated. Note that I will certainly address the doors at a later date, but for now I'm focused on everything behind the rear seats as sub-woofer is next on my agenda.

[S4Per]

No velcro needed except for back end of quarter panels i.e. right behind the cubby opening and potentially the back vertical section I.e. the inside of the bumper where the spare is. Glue takes care of everything else. I wouldn't over complicate it from there.

I covered just about 100% of my trunk with ccf/MLV. There's not much more secret sauce to it...and it can be quite a pain in the ass. Take a look again at my install thread where I showed how I had to modify the tire jack holder to fit again and also had to slightly trim the carpet so the metal cargo net holders could go in again and finally that I had to get longer bolts for those, too.


Sent from my iPhone using Tapatalk

[JWebb_C7_Comp]

Thanks for the note S4Per... I recall very specifically the longer hardware at cargo tie down (That's such a simple, but NOT obvious idea). I'll look at the jack modification too. I recall use of a Dremel tool somewhere; and I so seldom use mine....

What do you think about covering the back side of the carpeted panel INSTEAD of the detailed work you did to get down into the spare tire area. My thinking -- and I have NO IDEA whether it holds true -- is that if I covered the entire flat floor (and area immediately around that (i.e. where the cargo tie tie hooks are) -- plus the quarters, I'd mostly keep road noise out of the trunk (and, as a result, the cabin).. I'm looking to simplify, but keep same approximate result.

One thing for certain, I'm going to download a sound meter app to my phone. I'll test the car at a constant speed (same road, radio and fan setting) with my winter tires and then again with my summer tires to get "base" readings. Next, I think I'll test after having ONLY having done the "floor" of the trunk. Then, after having done sides, including both the MLV/CCF AND HMF. I stuffed some microfiber and a down jacket over the right rear while driving the other day and noticed a huge difference in that I couldn't "localize" sound out of that corner. I hope the HMF has that effect permanently.

My A6 is not as quiet as my wife's Q7, but then again, I'm running "performance" winter tires and they definitely have a bit of growl to them whereas her winter tires are remarkably quiet.

[S4Per]

I see what you're asking. Answer from me: I don't know. But not having ever heard of anyone else approaching it that way, I have to think it falls short somewhere?
Great idea with the sound meter. I wish I would've done a before and after.

[JWebb_C7_Comp]

Thanks for the note S4Per... I recall very specifically the longer hardware at cargo tie down (That's such a simple, but NOT obvious idea). I'll look at the jack modification too. I recall use of a Dremel tool somewhere; and I so seldom use mine....

What do you think about covering the back side of the carpeted panel INSTEAD of the detailed work you did to get down into the spare tire area. My thinking -- and I have NO IDEA whether it holds true -- is that if I covered the entire flat floor (and area immediately around that (i.e. where the cargo tie tie hooks are) -- plus the quarters, I'd mostly keep road noise out of the trunk (and, as a result, the cabin).. I'm looking to simplify, but keep same approximate result.

One thing for certain, I'm going to download a sound meter app to my phone. I'll test the car at a constant speed (same road, radio and fan setting) with my winter tires and then again with my summer tires to get "base" readings. Next, I think I'll test after having ONLY having done the "floor" of the trunk. Then, after having done sides, including both the MLV/CCF AND HMF. I stuffed some microfiber and a down jacket over the right rear while driving the other day and noticed a huge difference in that I couldn't "localize" sound out of that corner. I hope the HMF has that effect permanently.

My A6 is not as quiet as my wife's Q7, but then again, I'm running "performance" winter tires and they definitely have a bit of growl to them whereas her winter tires are remarkably quiet.

I did some testing and posted results in a table in the dampening thread I started..

Generally, my 18 A6 comp is at a little over 60 dB at 50-60 MPH. This is based on (7) tests, (4) with winter tires and (3) after I swapped to summer tires. Roughly 40 dB sitting with car on - no radio or HVAC - in the driveway. I used an iPhone app and plan to retest as I progress through the deadening process.


Sent from my iPhone using Audizine

[S4Per]

Very cool!


Sent from my iPhone using Tapatalk