I had my interior apart for various other projects – headliner repair, window motor and wiring repair (posted here), deep cleaning, etc. The OBS 7.3 is a little noisy, in case anyone here hasn’t noticed. So I figured if I ever wanted to do any sound proofing this was the best time. Started researching here, lots of good info on this site as usual. I took a slightly different approach from some folks here, and could not find many pictures or description of this approach on our trucks. So figured I’d do a quick write-up about it. I put in the post title the key words and phrases I was using to search and not getting many results, hence my alphabet soup thread title.

Before I get to pictures and such, want to make a couple quick points.

First, there are a lot of sound deadening strategies. Examples include off-the-shelf stuff, such as Dynamat, versus more generic construction products such as Lowes Peel & Seal. I do not intend to discredit either approach, both have their merit. Dynamat seem to be a readily available, decent quality, purpose-built product. And you can’t beat the price of the Peel & Seal product. However I was concerned with the commonly cited downsides of both, namely the cost of Dynamat and concerns with sometimes having and oily aroma with any asphalt based stuff. Another approach I read about is spray-on coatings but just didn’t get good feedback on these and I don’t have any specialized spray equipment. Again, don’t mean to discredit any of these strategies. Many solid reviews for each approach out there. And thanks to folks who’ve contributed about their experiences.

Second, regardless of the strategy, I did not intend to make the truck whisper quiet. If I wanted a common-rail quiet truck I would not have got one of these. My goal was modest reduction of noise at whatever frequency that just makes it hard to carry on a conversation. Hoped for this modest result at a reasonable price, with quality materials that would not offend. Hence the thread title, sound “damping,” because it seems there is no sound “proofing” the OBS 7.3 unless you just shut it off.

Third, there are some really basic fixes with factory materials that contributed greatly to this goal. Back this winter I put up a short silly thread about gluing back together the shifter boot screw bosses so I could get the manual transmission shifter boot secured to the floor better. This made a HUGE difference in sound coming in (significant measureable decibel reduction). Another example was replacing my door pin bushings and correcting the door alignment a bit so the door sealed better when closed.

While researching options I stumbled upon the SDS website, Sound Deadener Showdown, which is referenced here in a couple threads in the Super Duty section. I won’t go into all the theory behind it, you can read up on the website, great info there. The basic idea is to take a multiple layer approach using different product types to control different kinds of noise at different frequencies. Basic materials (and good key words for searching) are:

CLD tiles – constrained layer damper, foil-backed adhesive pads, controls vibrations, like putting your hand on a bell, very similar to Dynamat Xtreme or Lowes Peel & Seal only the SDS CLD tiles are really robust in thickness and use butyl and not asphalt.

MLV – mass loaded vinyl, heavy stuff that blocks a broad range of sound waves, maybe somewhat like the Dynamat Dynapad product

CCF – closed cell foam, works like a gasket for the MLV, creates a separation layer. Combines with MLV to make like an inner floor mat under your carpet or factory rubber mat.

HMF – hydrophobic melamine foam, very much like cleaner/eraser pads, also blocks a range of sound frequencies but is light weight for over head applications.

I liked the SDS approach with these various product types. There are some threads out in various places about using these product types, and a couple on Ford trucks specifically, couple here even. I just did not find one for an OBS 7.3 with pictures.

I assumed I could apply the basic logic here and find materials locally. However I had a hard time finding what I felt was an equivalent product at the same price point so ended up using the SDS stuff. I do not intend this tread to be a product endorsement as much as a strategy demo. But I was impressed by the quality of the SDS materials and had a good customer service experience there. So I was pleased with my experience with him/them.

So now here’s some pictures of how I put in the CLD tiles, CCF and MLV mat, and HMF on the roof in my OBS 7.3 crew cab. Sorry for the long setup…

First, gutted interior. Rode around in it all summer long like this. My projects don't go fast.




Panels behind seat belts came out eventually.


More coming...

 

Deep cleaning on floor mats...




Factory rubber floor mat was really dirty


Floor needs to be clean to stick on any product, had to remove dirt buildup...








Got all that dirt out, then let dry a couple days, and per recommendations on SDS site wiped down with alcohol before applying the sticky CLD tiles.

All clean now...




Took opportunity to clean door seals too. You can see foil backed tiles going on here.


Here's the tiles on the roof. Based on what I read on various sites, partial coverage will get you most of the desired results for controlling vibrations and resonance. So I think the recommendation is about 30% panel coverage. The SDS website gives a great breakdown of recommended number of tiles (his are 6 X 10 inches I think) per panel. I tried to stick to the recommendations.






I actually cut most of the tiles in half or into thirds, most of these products cut easily with scissors or a utility knife.


More coming, don't want to clutter each post up too much.

 

Filled the area between the roof bows with the melamine foam product recommended by SDS. It's like the cleaner/eraser pads, only with no cleaner. Need a light weight product over the headliner. Not sure these trucks get too much noise coming in from the roof, but I do not want to take my headliner out again if I can avoid it so figured if I ever wanted to do this now was the time. You cut the foam to fit and use some kind of readily available adhesive to glue it in, I used the Loctite product on the SDS site and it worked well. I used 3/4" thick foam here. I would not recommend going any thicker than 3/4" on these trucks as it seems to push the headliner down just enough to make it a bit difficult to reinstall. Wasn't bad, just had to carefully push it up a bit to align some of the screw holes. But then I had a terrible time with screws wanting to snag the new headliner material (which I guess I did not trim enough off of) due to the screws slight misalignment. Regardless of the minor challenge, it went back in okay. But I think thicker than 3/4" and you'd have a very hard time with it.




Pretty sure overlapping any foam over the roof bows would have made headliner not fit up in place properly.


Here's how I did the adhesive tiles on the back wall. The spaces there were large enough to use whole tiles, whereas I cut them longwise in half or into thirds or into smaller squares in most other places.




Sometimes I felt like I had enough tiles down, but I hadn't reached the recommended quantity yet so found another area to cover.

And here's the front, where I was pleased to see the factory sound damping material still in pretty good shape. The recommendation I got was to just leave it if it was still in tact. 




I also put some on the inside of the outer door skins and the inside of the inner door skins. The pictures of this area did not turn out great for obvious reasons, but here's one to get the basic idea.





With these on the inside of both the inner and outer door skins you can't really see them even with the interior door panel off.

 

So that was the easy part. The harder part was building the CCF-MLV mat for the floor. The basic idea here is simple: CCF (closed cell foam) goes on the floor, MLV (mass loaded vinyl) goes over top, factory floor mat or carpet then goes down over both. The MLV blocks the sound, the CCF is what they call a de-coupling layer, kind of an insulation or gasket to isolate the vinyl pad from the metal. You can apply the same logic to the doors, CCF would go against the door, then vinyl, then your interior panel. The MLV is very heavy (comes in various densities, I got 1 lb per sq ft vinyl. The SDS strategy for attaching it to the door is to use a really strong velcro. I'm sure this approach would work well for the doors, and there are a couple decent photos on other forms for this door treatment. But I opted not to do my doors, primarily just to cut down on the cost of the project. Figured with the 7.3 most noise comes through the firewall, floor and transmission tunnel. Due to the heat off the exhaust I opted to use the foil-backed MLV that SDS offers on this front portion around the transmission tunnel and firewall.

So this is not hard in theory. But the floor is not flat, so the vinyl doesn't just roll out and form-fit it. To make it fit the shape of the floor you can cut the MLV and CCF into smaller sections, and then glue a small strip of the MLV across the seam to join the two sections. I used the HH-66 vinyl cement recommended on the SDS site. It worked well, although I will point out for all the folks who worry about any Peel & Seal aroma, this HH-66 stuff has its own special fragrance that I assume rivals other materials (HH-66 aroma seems to dissipate after a few weeks). Again, does not sound hard in theory. But it was very time consuming. Maybe I went overboard trying to keep the mat too form-fitted to the trans tunnel, etc. But I did not want it to distort the way the factory floor mat laid down. I cut out a bunch of cardboard templates, then laid them out not the MLV and cut the MLV to shape. It cut easy with scissors and a utility knife. Then I cut the CCF to fit. Even though I was just laying it on the floor I went ahead and got some of the velcro strips to hold it in place. They worked well. You put them on the underside of the MLV and you cut a little notch out of the CCF to fit around them. Here's some pictures.




CCF and MLV (both plain and foil-backed) laid out in dining room floor (what better place for truck stuff?).

Here you can see the cardboard templates I used to trace and cut sections of the MLV to fit the shape of the floor.



Cardboard templates for CCF-MLV sections. Sectioning it off like this was not needed nearly as much on the back half of the cab where the floor is flatter.

Templates laid on MLV for tracing and cutting. I tried to puzzle-piece them together to best utilize the square footage of the MLV. It's worth noting, I got 10 sq ft to do the floor. It wasn't quite enough to get all the way to the back wall, probably because I went overkill with the seams to form fit the front around the transmission tunnel.




This photo just shows the pieces laid out somewhat randomly. I tried to rearrange them to make the best use of the space.


Here you can see the layering of the CCF on the underside of the MLV. With the foil-backed MLV the foil side goes down, toward the heat source. You can see here the velcro pads too and they way you cut out the CCF to go around them, so the velcro is exposed to the floor and the MLV.




I really liked the velcro strips as a way to hold this stuff to the panels. That way it can be pulled out if I need to access something, such as the holes in the floor for cab bushings.


Here you can see the sections laid out on the trans tunnel and front floor boards. Velcro held them in place until I could get the seam pieces cut and glued on to hold these together.




Sections of CCF/MLF laid in place, held in place with velcro on the bottom in places where it sits up at an angle. Seams get covered in next step.


The idea is to cover all those seams to create an uninterrupted blanket of the CCF/MLV combo. You use just plain MLV cut into 1-2" strips (no CCF needed) and glue the strip across the seam onto the edges of the two adjoining sections. Like this...




MLV glued across seam to act like a tape for to adjacent sections of the CCF/MLV pad.


I have read where some folks took their dash out to apply sound damping material back there. I'm sure that is a more thorough approach, but I just don't have the time and am half afraid I'd never get my dash back in. However I was able to peel back the factory foam material and get my CCF/MLV combo stuck up pretty high on the firewall, as far up as I think you could go without removing the dash.




Got it well up behind the pedal here and about as far on the passenger side.


And here's what it looked like around this very contoured area once I put the MLV seam pieces over the gaps...




Seams sealed up with MLV-only strips and the HH-66 used to glue them in place over the gaps.

 

The rest of the floor went much easer because it's mostly flat and curves up and down mostly in one direction. Here are some pictures of the rest.

I laid out the CCF first...




CCF on rest of floor, going faster now...


Then the MLV...




That was quick, wasn't it?


You can see in the picture I did one more sectioned and seamed piece for the little hump under the crew cab back seat. You can also see I ran out of material and could not make it all the way to the back wall. This was probably partly because I went overkill with the sectioning and seaming up front. But I think it's probably up front behind the engine where most of the noise comes from anyway. Here are a couple more angles of the mostly finished product...




Mostly finished floor, although this picture makes it look like full coverage...





Here you can see I didn't have quite enough to go down the slant to the rear doors. I would have probably done another sectioned and seamed piece here.


I had just enough material to make a small flap to cover the slant down toward the front doors. I seamed this up like the rest. But the rest of the material at this point was really small scraps, would have taken a long time to piece enough together to cover much else, just wasn't worth the extra time at this point. I got done probably 95% of what I intended to cover with the 10 sq ft of material I purchased.




Front floor area mostly covered, got in a hurry and got a little messy with the vinyl cement at the end, you can see the drips.

 

So the big question is: How'd it turn out?

Well, I think I accomplished my goal. I got a modest reduction in noise. I can talk to passengers without feeling the need to raise my voice, and they can hear me. They can speak back to me, and I can hear them without straining. It feels a bit more air tight when I shut the doors. Engine noise is slightly more muffled. Other noises are slightly more muffled. For example my ZF5 truck already had the DMF swapped out and has a solid flywheel, so transmission growl at low RPM was always very pronounced (even with good, new, proper fluid), and I could hear the throwout bearing a lot. That is less pronounced now.

Notice I keep saying "slightly" quieter, "modest" noise reduction. It is not tremendously quieter, no night and day difference. It is still kind of loud by comparison to other vehicles. I think the change is more qualitative than quantitative, more of a difference of feel inside now than a major measurable change.

For some empirical data I downloaded a simple decibel app on my phone (not very sophisticated, I know). I got about a 1 db drop. It went from about 81 db at highway speed on the app to somewhere between 79 and 80 db. Compare to mid 70s (74-76) in our 2005.5 VW Jetta TDI. I don't have the time or patience to get too much more empirical about it, but I gather even a couple decibels is pretty significant with sound control projects.

Question is, with all that work, am I okay with just a modest reduction in sound levels? Honestly, for that much effort I thought it would be quieter. In fairness, I stopped well short of doing the full treatment SDS recommends by not doing any CCF and MLV on the doors. But in reality yes a modest reduction in overall volume is all I was looking for. I'm okay with it the way it is, kind of like that I can still hear the engine just somewhat-less-loud and clear. In fact I was worried about making it TOO quiet, which is why I liked the velcro approach, figured I could cut a seam and pull some out if I went too far. I certainly did not go TOO quiet. Like I said at the beginning of the thread, if I'd wanted a super quiet truck, I would have a different truck. So a lot of work, yes, but overall I am please with it.

If you're interested in sound control on these trucks, there are other approaches, other materials, and no doubt better or worse outcomes. But I liked this strategy okay and was please with the vendor, SDS. Hope this helps if anyone is interesting in tackling this project.

 

Thanks for the awesome write up... I'll get around to doing some sounds dampening one day... Until then, my super loud stereo does the trick lol

 

Very nice job, and awesome write up!! Thanks!!

 

That's real thorough.nice job

 

Great write up! Sometimes, on our family trips in the Stroker it's not always a bad thing for talking to be hard LOL

 

That's why I am the only allowed to touch the radio.

 

Dragging this back up top to hopefully get some fresh links for suppliers. I have gone through a few of the sound deadening threads and it seems that SDS no longer exists and some of the product information links are no longer valid.

Edit:

I am adding a link to the 6.0 side for further information HERE

I am not an expert nor even a shade tree mechanic. More like a hedge mechanic so I really appreciate the combined knowledge of the forum when trying to learn something new like sound deadening...

 

Nate, I did some internet research today when I saw your post. Looks like the owner of SDS closed up shop, so he is not available as a supplier any more. I had trouble finding similar materials locally. If I was doing this all over again I guess I would either go with Dynamat or do some testing with Peel & Seal to check for aroma prior to doing a full treatment.

That said, honestly, I don’t think I would do it again unless taking the time to pull the dash. That seems to be the primary culprit for noise. I did all this work sound damping, then went and installed a 5” strait exhaust on my truck…about like ordering a diet soda with fries, right? So I undid a lot of my sound control, and sure doesn’t seem like I accomplished much now. Considering a muffler, and have new body bushings to install at some point, which will hopefully add some extra space between the firewall and downpipe.

However we did notice a difference right afterward, so presumably the exhaust would be even more noticeable without this stuff. Good luck finding something that works. Keep us posted on what you find.

 

I read this thread and it seems like you did a lot of work for marginal results. With the cab completely apart I figured I may as well give it a go. I do plan to cover everything completely except fastening locations.

 

I wonder about gluing egg crate behind the seat
Lots of noise from behind