Project STFU X5

[ucsbwsr]

I love the power, efficiency, reliability, and versatility of my diesel X5 but it's not perfect. My biggest complaints revolve around the poor ride quality and interior noise; the crackling, banging, and booms were driving me crazy and could really be an annoyance on an otherwise pleasant driving experience.

With the ride quality I experimented with a few different spring/strut combos and gains in ride quality were always marginal. I like my vehicles to have a clean stance with flush fitment and without excessive fender gap, that's just the way it is. After running Koni Red struts paired with Eibach springs I made the jump to KW V3s which I knew I would finally arrive at, I run them on my other vehicles and have been very pleased. They are an upgrade on the X5 but still not quite what I was hoping for in terms of comfort. I have them set to factory recommended settings which I haven't played around with, but will later. The ride is fairly firm but what really stood out is the transfer of sound when hitting stuff. The *bangs* and *booms* when hitting gaps in the road was really shocking.

This led me down the path of trying to silence and minimize the intrusion of these noises into the cabin and therefore, sound deadening. I have done a bit of this back in the day when I had 2 12" Image Dynamics subs in my E39 M5. I am still a bass-head at heart but am not willing to sacrifice the cargo area storage in the X5 like I was with my M5. With the M5 I used some constrained layer dampener (CLD) tiles from the now retired SoundDeadenerShowdown.com to keep trunk rattle to a minimum.

Flash forward to latter 2022 and sound deadening products have evolved into more refined, easier to work with, options for silencing the transfer of sound in different ways.

The products I used were:
Kilmat 80mil butyl/aluminum sheets
Noico Red 315mil and Siless 315 and 157 mil closed cell foam
JVCC Polyester felt tape (1mm x 3/4" x 75ft)
Various foam/rubber weather stripping for door seals.

80% of this project was installing the Kilmat all places I had access to. I understand the Kilmat (CLD tiles) are mainly for absorbing vibrations and turning the sound into heat and originally I read you only need 30-40% coverage on flatter metal surfaces to be effective. However when seeing modern installs from "professionals" they cover all surfaces. Considering the amount of work to gut the interior I figured I would error on the side of excessiveness to cover everything, even if it meant more product and a longer install time.

The E70 has a pretty thick foam under he carpet and the interior tolerances are tight so there isn't always room to install the closed cell foam, it was mainly added on the doors, cargo area, rear roof, and B/C/D pillars.

Installing the felt tape was a bit tedious but really makes a big difference. With the interior torn apart I applied the tape to all areas where plastic trim pieces made contact with each other.

My wife's 4M Q7 was a big inspiration for this project since the Audi has excellent sound insulation and cabin isolation in general. Both the Q7 and my in-laws X7 have robust weather stripping around the edge of the door, the X5 only had weather stripping around the inner seal (closer to the interior door sill as opposed to the outer edge of the door which seals between door when they are shut). I decided to copy this as much as I could on the X5, the thought is adding weather stripping between the doors gaps would help eliminate possible wind noise and also help dampen the door when being shut/slammed.

So this was the scope of the project. I will continue to add deadening when I can, like felt tape on dash trim or add more Kilmat on the firewall if I pull the dash or engine, or on the transmission tunnel / underside of the floor with the trans, driveshaft, etc. removed.

I am very happy with the results so far. Unfortunately I didn't take any DB reading so I don't have any quantitative before/after data but the X5 has a more "solid" feel and sound to it. There is still noticeable wind/road noise and in this regard it doesn't match the absolute isolation my wife's Q7 offers but I'm OK with this since a little road/wind noise isn't that annoying. It was the creaks, bangs, and booms which were the main objective and they are definitely muted.

My favorite part of this project is the sound of the doors when being opened and shut. With the added weather stripping, Kilmat, and foam they now offer a vault like *fffump* which is much more solid than both the Q7 and X7. Honestly the door sound is now similar to high end luxury vehicles like Merc S-class, Bentley, RR. It's just so good IMO.

The project was a lot of work but offered a lot of reward. The disassembly, cleaning, prep, installation, and reassembly just takes time, now way around it. You can do it in sections which helps break up the project. Ex, I first did the rear tailgate and some cargo area, did the doors in a second wave, and when I did the interior floor that turned into doing the floor, roof, pillars, firewall etc. since it makes sense to knock all of those out with the interior gutted.

Here are some pics!
Evan


Rear wheel wells



Outer door weather stripping
Before


After



Inner door weather stripping just around door panel



Before/After inside view



Rear hatch


Rear seats out


Treasure hunt


Heavy seats



Cargo time


Wiring harness and foam pulled back


After



C and P pillar getting Kilmat


D pillar + closed cell foam


B pillar



B pillar trim



Headliner down


OEM roof insulation


Removed


+ Kilmat


+ Foam


Checked pano roof drains while I was in there (this is how you know I also own an E61) lol


Subwoofer ports



Floor and firewall






Time to start doing the trim


You done yet?


Center console was a beast


One of the biggest culprits for creaks and cracks coming from the cargo area.







Front seat trim



Doors


So with an older battery and temps plummeting form the cold snap battery voltage dropped and my FRM module erased itself and consequently my windows wouldn't roll up and I needed to get the X5 out of the garage. I pulled out my DC power supply and found the electrical pins on the actuator so manually roll the windows up. Oliver helped.



Cargo floor

[Dekero]

Nice work! I owned my own Car audio shop for 20+ years and have done noise dampening work for years .... I can attest to the amount of work you went through to do this... And I can only imagine how much quieter the whole truck is now!! Great work.

[SlowX6M]

That is pretty freaking brave. No way I would endure a project like this on my own, but how much would a shop charge for a job like this? I'm thinking at least 5k?

[Nyc Dito]

Friggin amazing .. i was going to ask how much better the wind noise is now in your build thread, but after seeing the FULL thread I already know the answer.

My "STFU" project went as far as just adding felt strips to the cargo cover contact points..which actually helped. I HATE the wind noise I have always gotten.

Anyway, super dope sound deadening install.

[Daytonawim]

That looks great!

I did some against the metal of the rear doors and on the Floor from the back.
I had to check the seal, so that was easy. I used reckhorn alubutyl.
If you nock on the Outer door, now it sounds solid.

What wether striping did you use for the doors?

[RL18]

Wait a second where did those speakers in the rear seats come from? Isn’t our fuel tank right there? You’re giving me naughty ideas if there’s room our underseats there 😅

Nice job man. Don’t you love how fairly simple it is to remove the interior on these x5s?

[jbash87]

Originally Posted by RL18

Wait a second where did those speakers in the rear seats come from? Isn’t our fuel tank right there? You’re giving me naughty ideas if there’s room our underseats there 😅

Nice job man. Don’t you love how fairly simple it is to remove the interior on these x5s?

Easy, boy. HAHA

If you're talking about the "speakers" circled below then you'll be sad to learn that they are the covers for in-tank fuel pump(s).

[RL18]

Originally Posted by jbash87

Easy, boy. HAHA

If you're talking about the "speakers" circled below then you'll be sad to learn that they are the covers for in-tank fuel pump(s).

Lol that’s what I thought. Looks very similar though

[jbash87]

Originally Posted by RL18

Lol that’s what I thought. Looks very similar though

There is typically a bit of space underneath those covers... Perhaps someone motivated enough could make it work

[RL18]

Originally Posted by jbash87

There is typically a bit of space underneath those covers... Perhaps someone motivated enough could make it work

True! Really isn’t too much to be gained with 4 of our underseat woofers, I’ve tried it. Would need a sub with considerable output to supplement all the mid bass you’d get from them

[bmwboyee]

I would really be interested in the door seals and what was used. I'm not sure I will be tackling tearing the interior apart. Potholing will be the first large project.

[dvorak9085]

Hey mate,
Just came to tell you that you did great awesome work
Thanks for sharing with us!