Hapy Cab Gets Quiet

In my last post about noise containment, I posted about getting the main living area floor noise controlled with Heat Wave Jute and MLV. Before that, I posted about the application of the constrained layered dampener (CLD) on the ceiling and easily-accessed exposed steel (See Noise Control Update). There has been a lot of foundational work and many posts leading up to this next step. I removed the drop ceiling. I ran the rough electrical for the luxury items like accessory plugs, dome lights, etc (See Ceiling Wiring Rough In). I found and resolved holes from the old Westfalia pop-top. I removed the old shelf, designed and installed a new one (See New Cab Shelf). So finally, today, I will focus on getting the cab area practically noise controlled.

 

Cab Floor Prep

cab floor, nose quieted

Many years ago, I applied something CLD-like to the floor of the cab after addressing the rust with naval jelly and rust encapsulator (see Rust Never Sleeps). That post was so long ago, it pre-dated my now-common efforts to identify the products I am using, but I am fairly sure it was B-Quiet. Regardless, the stuff available in 2007 may not be as effective as the stuff available now. I suspect the old B-Quiet has since been reformulated to have more Butyl and less asphalt. So, I started working on removing that old stuff. It did not want to let go, and in some cases it left a sticky mess behind. I found that I was most effective at removing it when I cut 2" squares into the foil topper and removed a square at a time. For the spots where tacky goop remained, simple scraping worked a little, running the grinder was ineffective, and multiple passes of Goof-Off was moderately effective. After multiple rounds with Goof-Off, scraping was much more effective, and I was able to get most of the asphalt-y sticky off the floor. Still, the effort to remove that old stuff took most of a weekend.

With the old stuff gone I discovered that I needed to address rust in the floor again. Long ago, I abandoned Naval Jelly to get rid of rust, believing that it just is not as effective as the converters currently on the market. Perhaps, it was user error, but I followed the instructions. Anyway, this floor had been worked on with the Naval Jelly before I changed and it showed. I like Eastwood stuff, after trying and abandoning others. It is a simple spray-on product that I then spread around with a gloved hand to make sure it gets everywhere. It dries with a thin shell that could be painted on top of, but Eastwood recommends their encapsulator (of course) on top. I thought about adding another layer of paint, but decided it was unnecessary and left the floor "top coated" with the black Rust Encapsulator.

Cab Floor Noise Contain

Once the cab floor was rust treated, I applied some fresh CLD. Even the Noico was an improvement on what was there before. Before I started, the floor still had a fairly noticeable "ting" when smacked with the roller. Perhaps part of the reason the B-Quiet was not as effective was because it was trying to adhere to rust, not to steel and converted rust. Similar to the cab ceiling, I did the larger panels with the ResoNix, and did a few smaller areas with some leftover Noico. I had not previously applied anything to the walk-through, but that got CLD this time.

I used the rubber mat as a template for the next 2 layers: Heat Wave Jute and the Mass Loaded Vinyl (MLV). I under-sized the front edge so the kick panel/card that runs along that leading edge can seat against the floor later. Then, I did the walk-though floor with Heat Wave and MLV, following its basic rectangle shape.

 

Cab Doors Contained

door Mega Zorbe'd

The amount of prep work needed in the doors was not as extreme as the floor, but there were some needed steps. There was some surface rust down along the bottom and in the spots where the different metal bits intersect. After the rust was addressed and some Rustoleum was applied, it was ready to go. The steel also had some of that B-Quiet, but it seemed much more effective in the door than it was on the floor. I only removed the pieces that came off easily. Oddly, the passenger door stuff came off with little effort and the driver side stuff would not budge. So, the driver door was pretty much left alone (just CLD'd one section) and the passenger door got a full replacement treatment. Thinking about how much material I have on-hand, and how small an area I needed to solve, I used the Noico. While I test-tapped each door, I noticed both doors had a rattle that I traced to loose fasteners on the window mechanisms and door latches. A couple of passes of tighten-loosen-tighten eliminated those rattles.

 

Unlike the floor, I used Mega Zorbe in the doors. This stuff is so easy to work with. It is self-adhesive, so you figure out exactly what size you need, cut it, test fit it and when you're ready, you peel the paper off the back and stick it on. Of course, clean the surface really well first. The self-sticky is super-sticky, so I suggest the first time you play with it you apply it in areas which won't be seen until you get the hang of it. I got the 1/2" thick Zorbe, and it easily fit against the outer door skin without impacting the action of the window. If I have material left at the end of this project, I may apply some to the side of the door card that fits into the door cavity for more sound absorption. 

 

Nose Noise Contain

original Styrofoam

Most of the metal on the inside of the nose is inaccessible or at least very hard to get to. The pedals make getting to that lower section difficult, but not as difficult as the area behind the dash, especially on the driver side. Accordingly, I did not get very complete coverage of the inside of the nose with CLD. Before I could start, the bus originally delivered with some foam stuff glued to the lower section (below the mid-point). This stuff looks like old Styrofoam cooler material, and made a mess similar to a broken cooler with those little white dots everywhere. It was very thin, so I doubt it did much. Once removed, shop-vac'd and surface-cleaned, I used ResoNix, hoping to maximize the vibration deadening from covering such a small percentage of the total surface. I removed the windshield washer bottle and successfully fit a full one-foot-square sheet of ResoNix on the nose in that area. I cut a second square, fitting material up behind the glove box and onto the big metal airbox on the passenger side. On the driver side, access was even more limited. I was unable to fit a full uncut square directly in front of the pedals, but I was able to get a pair of rectangles applied there. I consumed the rest of that sheet plus another, getting coverage above the running light (beside the headlight) as well as onto the airbox. It is hard to know how much those sections will help, but I used the higher quality ResoNix, so maybe it will matter. Because of the foil topper, I figured putting CLD anywhere near the fuse-box would be a bad idea, so the whole upper left side is CLD-free.

I had originally intended to use the Jute inside the nose, but I changed my mind after wrestling CLD in there. First, the Jute needs adhesive to stick. Second, it is stiffer than the Mega-Zorbe. Third, the foil on the Jute is electrically conductive, so, like the CLD, we do not want it near the fuse box or electric controls. So, while we would have probably appreciated the temperature management of the Jute, there is no way I could have constructed a thermal wall in there. This is all about absorbing sound, and inside the nose can't be seen nor felt. So, I used and will continue to harvest for use, trimmings from other applications of the Mega-Zorbe and patch-work my way to sound control on the driver side. On the passenger side, I was able to place a single sheet of Mega Zorbe in pieces. The driver side was very difficult to get to, and handling the super-sticky self-adhere was not working out too well. I was able to get some larger cuts (maybe 4 inches by 8 inches) along the lower section, but that was about it. As I generate trimmings around the rest of the bus, I will return to the nose to add more.

Cab Ceiling

Mega Zorb'd ceiling

After all the efforts in previous postings, from the rough-in electrical to the mounting of the luggage tub and the shelf, I was finally ready to do the cab ceiling. Recall that the drop ceiling has been removed, the old shelf came down, and the original 1972 Westfalia supporting superstructure was removed. I used a combination of ResoNix and Noico for vibration control, thinking that an extra pound was worth minimizing the noise closest to my head. Similar to the doors, I used the Mega Zorbe on the ceiling. I covered the ceiling from lip to lip, front edge to the cross support. Simply sitting in the seat with that single layer of 1/2" foam was incredibly quiet just sitting in the driveway with the engine off. It is quieter inside the bus than outside. If I utter words, they are simply gobbled up by the noise control material in a more pronounced way than a gentle wind takes your words outside. I had originally planned for a second layer, and still may before applying a true headliner, but it will not be because I need more sound taken out of the air. It will depend more by how to contour the ceiling and remaining steel so the transitions are smooth. I will sit with it as-is for a little while, as I do other areas, to see how I feel about it. I may get some basic automotive foam if I need to add something. I don't have the headliner material yet anyway. Seriously, this bus is getting crazy quiet.

Under the Seats

view of the under-seats

Moving on to the seats, I used the Heat Wave and MLV combination again. Consider the little compartments along the inner edge of the seats. These compartments accepted 6-inch wide, 26-inch long Heat Wave on the floor. Against the wheel wells, another 26-inch long 5-inch tall stretch of Jute was set. Then, I got to thinking about the MLV. Consider, the access is very limited and the side of the wheel well is vertical. Simply brushing or spraying on contact adhesive was not viable. I cut 2 sheets of MLV for each compartment, with a combined overall average length of 25 inches each (d-side shorter, p-side longer), but 12 inches wide. Dealing with a half-length, I rolled it up and stuffed it through the access hole, unrolling the 12-inch width in place. So, the bottom edge is against the inner edge where it meets the floor, and the MLV runs up along the side of the wheel well with the top edge roughly against the ceiling. I set the second sheet in similarly, and with an overlap, the compartments are covered.... mostly. The driver-side compartment has the brake reservoir and tubing, so I was not able to get as deep. Hence, the shorter length of MLV. Still, I knew this was not going to be 100% sealed/covered. This is about as good as I could have expected without putting MLV around the outside of the entire seat pedestal, but that would have intruded into the limited walk-through space, for what I think would be little improvement. I accept that the MLV may not stay in place long-term. Since there will be a card on the walk-through side, I can access it and check up on it periodically. Being honest, I probably won't. If I have left over MLV, maybe I will figure out a way to put it inside the walk-thru card. We'll see.

Other than the little compartment, the under-seat space was controlled rather simply. I put one piece of both Heat Wave and MLV under each seat, running from the outer edge of the little compartment (under the seats) to the door's edge. To fit, I cut a channel around the outer seat runner. I thought about lifting the seats, but decided that having an additional 1/2" of squishy lift was not desirable; having some noise travel through the rails was an acceptable tradeoff. After the seat compartment efforts, we are no longer looking at 95% containment anyway. Between the inner seat rail and the inner edge, I set another section of Heat Wave, covering up the remaining bits of steel. This final section was not rectangular since the seat pedestal is not exactly square, but it rests above the little compartment, so MLV was unnecessary. The Heat Wave, however, will allow the carpet to lay flat.

Wrap It Up

Once installed, I taped all of the MLV bits together. Why? Audiophiles suggest that the MLV works best when it hasn't any breaks in it. I know there are breaks under the seat rails and inside the little compartment, so the tape may not be as effective. Still, the metaphor I have read is that the seams are like slightly cracked windows in your house, letting in the noise of your neighbor mowing their lawn. If the window is completely closed the noise is much more contained. So, having lots of open seams is like lots of cracked windows, versus a couple around the seat rails. Since I have not been taking noise measurements along the way, I cannot say whether the patchwork MLV will help meaningfully more than just the CLD and Heat Wave. The sound experts swear by this stuff though.

At this point, I have the floor completely noise contained, from rear hatch to the front nose. We have CLD to contain the vibration, Heat Wave to absorb some of the sound that makes it through and MLV to block most of whatever remains. Since most of the noise comes from the engine, drivetrain and wheels, the work to date should have addressed most of the problem. I am continuing down the noise elimination path, though. I will be applying Mega Zorbe onto the rear ceiling, adding some deadener between the 2 rear ceilings, and solving for the slider and mid-bus driver-side wall. I feel that I have turned an important corner, however.

That's it for today. Thanks, as always, for following along-

Noise Control Continues

With Summer tour dates heating up, and our favorite festivals appearing to be taking the Summer off, I was lacking an out-of-town overnight show to really kick this effort into high gear. Well... Phil Lesh and Friends have announced Pacific NorthWest tour dates, hitting 2 of my all-time favorite outdoor venues: the Cuthbert in Eugene, OR and the Marymoor in Redmond, WA. Phil played these 2 venues back-to-back with Further in 2013 (See Tale of 2 Trips), so I conclude that these are his favorite NW outdoor venues too. Anyway, June 11 and 12, Phil will be at the Cuthbert and Marymoor respectively, and so will we. With that, we have some serious motivation to have Hapy buttoned up by the end of May. In that spirit, I finally got after the big sections of the floor, so today's post is all about that. 

Tear Down

starting the Jute

I accept that maybe I have been finding ways to delay the full-blown interior tear down. I messed with electrical (See Ceiling Wiring Rough In), built a replacement shelf (See New Cab Shelf), even messed around with the stereo (I will post on that once it reaches completion). At some point, I was going to have to remove the lot couch and the rock-n-roll bed so I could get after the floor underneath them. The lot couch removes easily enough, but the sliders also needed to come out so I could get the complete floor. Back when I first installed these runners, I mounted the runners with 17mm bolts. I added nuts underneath. I initially just loosened the runners and forced the Jute underneath. I later decided to completely remove the runners so I could get a seamless heavy vinyl sheet down.

My implementation of the rock-n-roll bed is held to the floor by a pair of Phillips screws holding a pair of arms to the rear deck, a 17mm bolt underneath, a pair of small nuts on a metal bracket mounted on the passenger side rear wheel well and a single 13mm bolt through to the fridge cabinet. The electrical bits, however, add to the complexity. I have my luxury fuse box under there, so I had to tear down what was left of that. Plus, the original Westfalia electrical includes the cables routing city power into the rectifier (110 to 12V converter) that's buried inside a wood box and running to the outlet on the front face of the bed. The box is held down with 2 Phillips screws and the outlet box is held by 4 Phillips screws. With the electrical separated from the bed, and the bed detached from the floor, I removed the cushions to manage the unit better. Each of the 2 cushions are held to the bed with 4 long Phillips bolts on each end (so, that's 16 bolts).

cabin Jute mostly complete

I would have completely removed the fridge cabinet, but the mounting of the furnace was so difficult, I did not want to revisit that. Just being disconnected from the rock-n-roll bed loosened it enough for me to fit materials an inch or so underneath it.

Constrained Layered Dampener (CLD)

I have probably posted enough on this material. Still, I applied on the now exposed floor areas. Parts of the floor had already gotten a light treatment in the little valleys, so on top of that I applied larger squares of CLD as well. I still have about a third of the box of ResoNix, with a plan to use some inside the sliding door. I have used some of the Noico around as well. For example, the walk-through partitions behind the front seats each got a large splat of Noico. I do not know if I will be keeping those partitions long term, so I did not want to spend the expensive CLD on those panels. Still, the Noico definitely helped reduce the clatter heard when I tap on the partitions with the roller. Of course, the whole floor and the rock-n-roll bed needed a thorough cleaning, starting with a shop-vac and ending with cleansers. 

Heat Wave Jute

MLV over engine

I was so excited to finally get to the Jute. I has felt like forever since I ordered this stuff and started working on noise containment. I started with a rectangle on top of the engine access hatch, with an extra couple of inches all the way around. I pulled the computer cover, and Jute'd the rest of the rear deck, and then moved forward. I fit a segment under the rear edge of the fridge cabinet, and doubled up over the front side of the rear driver wheel well. I pierced the Jute for the seat belts and a grounding screw, and set another piece of Jute up to the lot-couch rear slider and continued my way forward, covering the entire floor with rectangles. My method was to define as large a section as I could easily manage and then measure that out on the material. I marked the line with a sharpie and then traced the line with a box-cutter to start the cut. I made a second pass with a pair of scissors. I tried first with just the scissors, but the thickness of the material and 2 foil-faces were too much even for my best pair. As I set shapes down, the bus got progressively quieter. Without a radio, and just ambient neighborhood noise, there was not a dramatic change, it just felt more and more quiet. Very neat. One last observation about the Heat Wave: the foil top and bottom are electrically conductive. So, I would discourage use anywhere near open circuitry or be sure to insulate. For example, I took a section of excess MLV produced below and have it resting between the foil and the spare tire well where the engine computer and fuse box live. No sparky.

Lot Couch Rails

I had loosened the rails enough to force-fit some of the Heat Wave jute underneath, but decided that getting the MLV under the rails would be worthwhile. This meant removing the rails entirely. I had forgotten that when I first installed these rails, I ran bolts from above and nutted from below. Three of the 4 nuts were hidden by the radiator, so getting in there to free them was an all-morning exercise. Still, the nuts came free, the bolts pulled out and the rails were set aside. I took this opportunity to clean under the rails as well as install 4 riv-nuts into the old holes, so I would not have to go under the bus and reach around the radiator to deal with the rails again. That riv-nut kit is definitely paying dividends.

Mass Loaded Vinyl (MLV)

MLV continues

MLV is heavy; my goodness, it is heavy (1 pound per square foot). I found that the sound inside the bus actually brightened a little bit as I set it on top of the Jute, though. The Jute, in contrast, was simply amazing in how much quieter the bus seemed as I added it to the floor.  While I can't measure the impact of the MLV independently of the rest of what I am doing, I do wonder if the additional weight will translate into a corresponding reduction in noise. The SecondSkin web site has a noise transfer reduction table for the MLV that defines the reduction as anywhere from 14dB to 37dB, depending on frequency, with higher frequency blocked more than lower. We'll see. The actual absorption by the Heat Wave was noticeable. The table on the SecondSkin page for Heat Wave (in coefficient rather than dB) demonstrates very little in terms of dB drop below 500Hz: below 500Hz < 3dB, 1k: 7db, 2k: 14dB, 4k:19dB. So, the very high end will be controlled well and the low end not so much. I arrived at these numbers courtesy of the formulas on this blog post, converting the coefficients published by SecondSkin.

Anyway, the MLV delivers in a roll 54" wide. The bus is around 60-1/2" wide so rather than solve for a strip along one side, I laid a section 54" long front-to-back, covering the engine compartment and on down the rear wall behind the rock-n-roll bed. After cutting contours for the narrowing of the rear of the bus, I pierced the MLV for the seat belts and installed them. This took a considerable amount of time, mostly because of the challenges of getting the seat belt mounts in place. I continued with the next sheet of MLV, covering the mid-floor past the lot-couch rail mounting points (see picture above, right).

Re-Assembly

bed and rails in

I chose at this point to re-install the rock-n-roll bed. Unlike the seat belt mounts, locating and piercing for the bed mounts was much easier for some reason. With the bed in place, I pieced holes for the lot-couch rails and installed them. To make a more firm mount to the floor, I added a nut between the rail and the floor for the bolt to pass through. These nuts act like a 3/8" riser through the Jute material. I confirmed the width of the rails (12") and then torqued the bolts. Then, I put the lot couch back in. The couch slid in more easily than it used to. I think the rails were slightly below the lip of the sliding door before, creating some friction/resistance. With the little risers, the couch slides right in. The interior is pretty much the way I started the weekend. Yes, from the start to end of this post, it was 2 full-for-me (6+ hours) days of work, and some uncovered sections remain.

On a random mid-week afternoon, I added an additional strip inside the rock-n-roll bed where the 2 larger sections meet as well as a small piece inside the fridge cabinet. Last, the area just in front of the fridge cabinet shown in the picture above was addressed. So, from the seat partition rear-wards is pretty much done. That leaves the cab still to do. All of the seams need to be taped as well, but that should be much easier once the rest of the Heat Wave and MLV have been laid out.

In case you were wondering, that reflective material in the wall behind the fridge is foil-backed "RV insulation" that I had put in there years ago. It actually does reduce the temperature inside the bus a little bit, or it did when I first installed it. Since it does not fill the cavity, I will probably just leave it and put the Mega Zorbe or Jute right on top if it. There is the old Q-Quiet vibration absorber on those panels as well, and I will just leave that be. I am running out of material, and this project has taken quite a bit of time already.

That's it for today. Thanks, as always, for following along-

Hapy Noises - Part 2

Today's post continues the thinking-through-my-fingers on noise containment in Hapy, the 1972 camper microbus powered by a turbo diesel engine from a 1998 VW Beetle. This time, we look at the layers of noise control which appear on top of the vibration dampener I mentioned in part 1 (See Hapy Noises - Part 1). Then, I cover some decibel collection I did so we have a starting point for measuring success or failure of the various layers.

Sound Absorb

Second Skin Heat Wave (Jute)

With the Constrained Layered Dampener (CLD) chosen, I wanted to add noise absorption stuff as well. In my research, I arrived at 5 different product types that could help. There are plenty of other choices, but I think by combining these, I will achieve my noise control goal. These act differently and have different strengths, so some are better in different locations and some are best used together.

Jute Thermal - absorbs sound, but is really more for temperature containment. This is similar to old-skool car insulation, but it is lightweight, and actually does absorb some noise. I intend to put this (HeatWave) over the engine compartment, under the rock-n-roll bed (on the floor) through the main cabin, under the front seats and to the front kick panels. It will act as a 3/8" thick carpet pad while keeping road noise and heat down. The Heat Wave product is designed to resist mold, etc, so even here in the rainy Pacific North West, it is safe for use. Of course, getting it soaking wet is not advised, so some thought about where it should be placed is suggested.

Second Skin MLV

MLV (Mass Loaded Vinyl) - blocks the transfer of airborne sound. Some products have integrated foam to absorb sound as well. These sheets are heavy for their size, and folks have expressed difficulty in getting them to hang vertically (like on a wall) or horizontally (on a ceiling, eg) permanently. I intend to use this stuff (Luxury Liner) from tailgate to toe-kick: under the seats, the rock-n-roll bed and the entire floor on top of the jute. By having the jute layer in-between, the MLV is more effective. The audio guys use this stuff behind their door cards too, but I'm not sure I'll have the money nor patience for that. The luxury liner is 1/8" thick, so, anywhere this goes on top of the Jute, the carpet will effectively have 1/2" of pad, which would be a little thick anywhere people are walking around, but the MLV will effectively stiffen the underfoot feel. It won't feel like you're walking on a 1/2" cloud. Using it under the seats will be fine, provided it doesn't interfere with the operation of the seat. This stuff is super important for noise containment; the audio experts / competitors swear by this stuff. I am toying with the idea of creating a "box" of this stuff inside the engine compartment to really cut down on the transfer of the engine-din. I'm not sure how that would all work. Again, thinking thru fingers.

Second Skin Mega Zorbe

Acoustic Foam - There are literally hundreds of different acoustical foam in all kinds of contents, shapes and sizes. Most are not all-weather-safe, and some are rather thick, so the options for smaller spaces where water or humidity might appear reduce that list from hundreds down to tens. That's still a big list. I plan to use this stuff (Mega Zorbe) in the doors, walls and in the ceilings. Of the materials, this is the most expensive, but it may be the most effective in dropping the overall noise. It is 1/2" thick, so anywhere it goes it could make it's presence known, so I can't use it on the door cards, for example, but it can go into every body cavity. There is definitely 1/2" between the wood drop ceiling and the steel, so even after that wood is removed, we would not lose headroom by adding the Mega Zorbe to the ceiling. Omitting the wood drop ceiling removes a sound reflecting surface I would otherwise need to deal with as well.

Open Cell Foam - I will be putting something on the door cards. I may use an open-cell foam product. Second Skin doesn't offer anything, but that's because there really isn't a product that will meaningfully absorb sound that's less than 1/2" thick (aside from the jute) and they are in the sound control business. I want something that will soften-to-touch and maybe reduce some of the sound reflection. For that, any old thin foam would do, because pretty much any soft surface that's, like, 1/8" thick will reduce the sound reflection. Or so they tell me. I will probably order something from McMaster-Carr (like this) or foam by-the-yard (like this) from FoamMart unless I can find something from an automotive fabric place. Regardless, any time we use open-cell foam, it is best to put a moisture barrier material between the foam and fabric (like this) to protect the foam from moisture as well as protect the fabric from rubbing against the foam. I haven't decided if/how I will address the hard cabinet sides. They might get the foam/fabric treatment just like the cards.

Closed-Cell Foam  - Similar to the open-cell foam in terms of flexibility and possible uses, but closed-cell foam is not permeable, so water can't get into it, damaging it. Closed-cell foams are usually stiffer and do not absorb sound as well. I may use closed-cell foam for the door cards instead of open-cell, if I can find something that acts like an open-cell, but is water-resistant (like this Volara or this Ensolite). There are closed-cell products designed for placement between your plastic bits and the steel. I had thought about getting some for between the cards and the body. I still may, but the rough cost of this effort is already a bit nutty and I can always do that later. For now, whatever foam I put on the door cards (under whatever fabric I put on there) may simply wrap around to the backside. Hopefully, that will contain the card-to-body rattle. Of course, I may just omit foam and fabric on the cards if money and time are not available.

 

Noise (dB) Level Tooling

Before we do any of this great stuff, I want to know where we are starting, so we can measure and celebrate the gains. My sitting-in-seat frame of reference for noise: I needed to run my stereo at 25 or above to be able to hear it at all over the noise of driving down the highway on the way back from Hapy's birthday (See Hapy Turns 50). I had the volume at 30 for loud-enough-to-sing-along (but not entirely taking over) volume. That is not at all scientific. So, in the Fall of 2021, I set aside the new driver seat install, took Hapy for a spin with the old seat and recorded these values for future comparison. My "tooling" was a free iPhone application called "Decibel Meter". I chose it because the free version allowed me to save many recordings, complete with graphs, for looking back upon. I was also able to email myself 5 minutes worth of detailed data. None of the other apps which also have a reasonable scale for the dB provide those features for free. I tried a few apps I won't name which had completely inaccurate dB readings. I used "Decibel X" as my control for comparing other apps. Decibel X is great, and very accurate, but you can't record more than 1 session, nor share anything without a hefty fee. I would have used it for my tests, but I would have needed another person in the bus, watching the meter, writing things down. That's silly.

I thought about buying a measuring tool for better sampling. I decided that I was already uneasy about investing a considerable amount into solving the problem, and chose not to spend more on a measuring device. Having better calibrated results, and more accurate frequency levels would have been great. The issue is that a decent point-in-time tool (Extech 407730) is at least $80US. An OSHA-qualified tool (REED Instruments R8050) is closer to $200US without data logging, while a fully functional tool (like Extech 407750, or REED Instruments R8080) can be over $300US. Plus, you need an additional device to periodically calibrate the instrument (for another $100US or more). I'm sure these devices are better than my free iPhone app, but I need that cabbage to cancel the noise first. Having said all that, if this sound control thing is a fun project, I may get a good tool so I can better measure before and after on future car projects. The trick will be finding one that is reasonably priced, accurate, can be easily re-calibrated and has a logging function so I can collect 30+ minutes of data without having to write things down as we go.

Noise (dB) Level Tests

For the test, I idled in the front driveway, and then took our usual route to the highway (OR217) from home, and drove a loop (OR217 - US26 - Murray Blvd) back home. This got multiple samples of idling, around town and byways. I only got one real highway sample, but I think it was long enough. I got up over 65mph for a short stretch, long enough to collect a sample.

Decibels from that long test are below. One important observation throughout all of the tests: the dominant frequency of the noise appeared at the very bottom of the spectrum. This could be a reflection of the tool not reading frequency well, or my noise problem is 95% below 100Hz. Some comparisons on my couch between the 2 apps indicated that Decibel Meter reads Hz low when compared to Decibel X. Neat. I chose to ignore the Hz, and accept that I can only really measure overall dB. On to the dB readings! In all cases, the value moved around within a range as well as had an overall peak:

dB test as a graphic

Sitting at idle (900 RPM): 60dB

Around town (less than 40mph): 65dB +/- 5dB. 75dB peak

On the byways (above 40 but under 55): 65dB +/- 10dB

Highway speeds: 70dB +/- 10db, 83dB peak

Over the course of the 30 minute test, noise was consistently between the mid 60's to mid-70's with spikes up into the mid-80's.

For fun, I compared against Boo's 2009 Audi A4 (GoRo) on my old standard test-drive loop, and then ran Hapy on that same test loop. This loop does not include a highway, but it does include idling, a residential street and a 4-lane "by-way". The Audi ran from the upper 40's to the lower 60's. Hapy on the same loop was in the low 60's up into the lower 70's, topping at 75dB.

Noise (dB) Level Test Thoughts

In simple comparison, GoRo was in the lower 50's most of the time and Hapy was 10dB louder or more. "10" seems like a small number, but I consider these 2 things: First, the range for both vehicles remained within about a 10dB span with Hapy's quietest/lowest readings starting at the loudest/highest for GoRo. Second, a modern refrigerator or a moderate rain is 50dB and hearing damage starts at 85dB, so a 10dB difference in this range is actually huge. I think it is kind of like 10* difference in Celsius: 23*C (73*F for US folks reference), is totally comfortable, like a conversational 60dB. But 33*C (91*F) is intrusive-hot, like a running vacuum cleaner 70dB. Another 10*C (43C or almost 110*F) is quite uncomfortable in practically all climates, like listening to a whistling kettle (80dB) for an extended period of time would be. For some real-life decibel level references, I found this link to be especially fruitful. Last, I think it is worth noting that the highway was much louder. My usual shift point is around 3200 RPM, and I cruised the freeway around there as well. So, maybe the noise gets much louder above 3k RPM -OR- the increased speed leads to more noise (wind or tire). I can't know for sure without more tests, but I think resolving the highway noise will be my biggest challenge. It would be the greatest reward for longer trips, if I can solve it.

EDIT: I added the image just above  on the right on 2022-Mar-29. I sourced it from a research paper about the dominant frequencies produced by a 3-cylinder diesel engine. While this may not be an exact match for a 4-cylinder TDI, I think we can draw sufficient parallels to lead us to focus on frequencies above 250Hz, but especially around 1k. Based on the material sheets for the items described above, all of these should make a meaningful impact on containing the noise.

That's it for today. I have more planning to do, and things to purchase. If all goes as I hope, the noise control efforts will start soon. My goal is for Hapy's entire noise range to drop by at least 5dB on the test loop and for the mid-80's highway peaks to drop by at least 10dB.

Thanks, as always, for following along-

Hapy Noises - Part 1

Today, I share my thinking around how to reduce the din when driving Hapy. He's a 50 year old bus. He runs a turbo-diesel engine. How quiet do we want to be? Or should I say how quietly do you want to spend? Or, maybe, how quiet do I really think this can get? I am actually taking this on, slowly, over the course of the winter and spring with hopes of a more comfortable drive experience when camping season really open up. For now, I will just put my think into words because what's a car person to do when s/he can't work on their cars? Thinks about them. Like so many posts, this got really long. So, I split this up. Today's post will cover controlling the resonation effect with constrained layered dampener material.

Before I begin, Hapy Groundhogs Day. Regardless of what the critter in PA does, it will always be 6 more weeks before the Spring Equinox. Here in the Pacific NW, it will rain until then. With expectations set, let's go.

Constrained Layered what?

Other places do a better job of explaining this. For our purposes, a Constrained Layered Dampener (CLD) reduces vibration by transferring that vibration into heat, which then dissipates. These materials have 3 basic components: the adhere layer, the butyl layer and a foil layer. The adhere layer is obvious: it is the super-sticky that gets the CLD to stick to the metal that vibrates. The foil layer is also sort of obvious: this is the top layer that you see when it's done. The butyl layer is the key: this is the science part that accepts the vibration from the adhere side and the vibration-resistance from the foil side. The butyl does the work of trying to get the vibration to stay put by equalizing between the two layers. The better the quality of the butyl layer, the more effective it will be per square inch. Again, there are better explanations out there, but that is a basic high-level summary.

Noico / FatMat / Hushmat / Kilmat

When I did the work on Oliver (1978 MGB), I used the Noico noise deadener stuff sold via Azn. I had read around the web that it was pretty good stuff, but when you are reading about what amateurs did on forums, it quickly becomes an echo chamber. Many forums dedicated to home-wrenching have posts that ask about one or more of the products listed above. Since most folks only ever use one on that one car, and aren't doing it professionally, the general consensus on Noico is "it's good". For the most part, the testing I have seen put all of these (Noico, FatMat, Hushmat, Kilmat, etc) in the same mediocre category. They sorta work, but you need a lot of it for it to get anything out of it.

Slamming Amazon side-bar.... Azn is excellent at hyping a mediocre product; this happened with Noico. We, as consumers, are led to believe that the marketplace will decide, and if people give positive reviews of something, it's probably fairly good. This works for products or services with which we all are somewhat familiar. Want advice on a TV or a phone? The market will weed out the garbage eventually. The issue is created when someone buys an inferior product about which they know little in a product market about which they also know little. Their experience goes from sucky before it arrived to perceived slightly-less-sucky. So, they think the product is fantastic, because they think life got better. What they may not realize is that they really did not make their life that much better, if at all, for the money they spent. They invested a small amount of money (like $2 per square foot for Noico) and a bunch of time, and when the noise in their car seemed reduced, they figured it was the product. Maybe it was. Maybe it was simply from removing the panels, cleaning a bunch and putting them back on. Most likely, the reduction was not as great as it could have been had they used a genuinely good product. The misperception is then influenced by the amplification of the echo chamber and the desire to not be taken advantage of, so a belief that the product was good is formed. And, the feedback loop continues.

In the convertible, I didn't know any better and, frankly, it doesn't really matter. It is a convertible running a carburetor and an aftermarket header; it will be loud when driving around. That's actually part of the fun: put your foot in it and it goes "waaah!". I put the Noico in the doors and now they have a nice "chunk" noise when they close. Same goes for the trunk. I think the overall din from the drive train is lessened because of the full-floor (both cabin and trunk) install I did plus the liquid rubber liner, the insulation and thick carpet. Exactly how much the Noico helped is unclear. For Hapy, I have way more noise control opportunity. It is not a convertible, and there may be 4 times as much steel panel to resonate-control. I had put something on some of the panels years ago (like the old brown bread, delivered in a roll, smelled bad), so it is not completely bare. I don't think that stuff was terribly effective, but it was what was available 15 years ago.

DynaMat, Second Skin and ResoNix

For learning about quality, viable noise control, I hit the car audio forums. I figured that if they were using something that helped them win car stereo competitions, it would probably do a good enough job lowering the noise in Hapy from incredible racket to tolerable. At least, they would know which lower-price options were actually worth using. In my research, I also engaged with Second Skin audio, and will use their stuff above the CLD (constrained layered dampener), which I will detail in another post. For vibration noise control, though, I am using ResoNix CLD. This stuff is super expensive, compared to Noico, but only a few cents per square foot more than the Second Skin stuff. DynaMat usually appears at the bottom of this higher-quality group, by the way. Based on the testing evidence on the ResoNix site and in the audio forums, the ResoNix stuff is really next-level. In the end, I will need to apply far less material than Noico, which means less work and less weight, while enjoying better vibration noise containment.

Install How

Install for any of these products is simple: clean the area to practically food-grade clean, measure and cut to fit with scissors, pull the backing paper and press it in place. Then, with an installation roller, roll around on the foil to get any air bubbles out and to ensure a quality adhere. Don't damage the foil; I can't emphasize that enough. Also, if the surface isn't clean, the product will not adhere as well, defeating the purpose. The amount of CLD you use is directly related to the product you are using, though the larger the uncut piece of CLD you use the better it will work. Meaning, if you use a bunch of small pieces over a section of metal, it will be far less effective as compared to one single piece. The strength of the CLD effectiveness comes from the foil topper preventing the panel from moving. This forces the vibration energy to change shape into heat energy as the Butyl tries to adhere to the metal yet retain it's shape as defined by the foil topper. If the sheets are tiny or if there are tears in it, there is less constraining, so more room for the metal to move, and much less of the vibration is converted to heat energy.

I found 2 different types of rollers on the market. The one in the image below has a completely smooth roller for foil-contact. While it may lose traction on super-smooth foil, it will probably not accidentally tear the foil. I say "may" and "probably" because I bought the other kind that has ridges running across the roller surface. That kind of roller can tear the foil, but it definitely does not slip. Ask me how I know :) Buyer beware, and if you get the same kind I did, mind you don't get too zealous with it or you may apply splits into the foil.

Coverage

Something like Noico will require nearly 100% coverage to get anywhere near the same amount of dampening as 25% of something high end. Under-apply and the vibration noise may just lower in frequency, not the full resonance so the vibration does not actually get resolved. So, you will think it's better, but you just lowered the note. If you watch car shows on Speed/Velocity/MotorTrend, you will see that those guys cover 100% of the interior and trunk (though they never broadcast the application. No sparks = bored producers). If you have the money, and haven't a worry about weight, I imagine doing the entire car, covering every square inch like that, provides maximum vibration reduction. There are diminishing returns though. Some small areas hardly vibrate / amplify car noise at all because they are small or have multiple connection points and can be skipped. The key to maximizing your product application / minimizing cost is to focus on the large flat sections first. Whether material should be multi-layered is a frequent question. The common understanding, demonstrated with some testing, is that layering product is money and cost ineffective without much return. That doesn't stop folks from doing it. Your project, your choice. I would suggest what the high-end manufacturers say: if you are willing to buy multiple layers of less expensive stuff, why not buy the good stuff for the same price and far less work/weight?

When I apply CLD, I can't help but tap on the area with the roller handle before and after I apply it so I can hear the difference. Before, it sounds tinny, after, it has more bass. Is this a reflection of what the vibration effect will be? Oh, heck no; I just can't help doing it. It feels like you're doing something. The only real tell is after you're done and you go for a drive. With Hapy's diesel engine running, we will get a fairly good idea without actually getting out on the road. My hope is that after I have finished, driving Hapy will no longer feel like you're operating a diesel generator inside an old leaky steel shed during a wind storm.... like it does now.

Liquid Deadener

One last thing on deadening: there are liquids that deaden too. These fall under the Liquid Applied Sound Deadener (LASD) umbrella. Second Skin sells "Spectrum" (see here), but there are others, like LizardSkin, dBSkin and QuietCoat. Since these products target the same thing as the CLD does, I thought I would mention it here. Based on the studies and the science of the CLD, I am not convinced the liquid works as well. The product websites don't specifically say how effective they are in decibel reduction terms, but for hard to reach spots where getting a sheet of CLD is not practical -OR- for exterior areas like the under body or wheel wells, this may be better than nothing. Or, this could just be fancy marketing of what amounts to liquid asphalt painted onto your car, reducing noise like a cheaper CLD does simply by being a thick coating. For the coverage, the liquids are much more expensive per square too. Still, I am going to try Lizard Skin in the spots I can't reasonably get to with CLD (wheel wells) because I want to try it out. I may hit between the belly pans and the floor, since I can't get in there with anything other than an undercoating nozzle. If it does little for the noise, but it helps retard the rust, it would still be worth doing, IMHO.

Next time, I get into different materials for subsequent layers, as well as some decibel readings for a "before" image to compare against after I add some of this stuff. Thanks, as always, for following along-