80s Interior Sound Deadening and Insulation Installation

[guzzla]

Anyone who has any engine and exhaust modifications will usually notice an increase in cabin noise, and sometimes heat, as part of such modifications. In my case, a set of extractors that went into a 2.5in system running directly under the driver's floor pan, along with the use of one straight-thru muffler and a resonator at the end meant I made some decent power gains for my efforts. The down side was during the hotter months, where the radiant heat made the interior noticeably warmer and the DS floor pan made it too hot to drive bare foot. Also, on long drives, the drone from the exhaust system filled the cab and made listening to music and conversation with passengers or on the UHF radio difficult at times.

Throughout the last 7 years I've owned this 80s, I've chased a few water leaks which have always been related to leakages via the windscreen an, on occasion, a floor grommet that had come loose or an unplugged bolt hole. The last 2 years have been incident free until recently where I noticed the DS carpet was noticeable wet and I'd not driven the vehicle for several months. Upon pulling back the carpet to see what was going on, the following images tell the rest of the story...

Water filled gutter on drivers side


After the water was drained, a thick layer of mud remained


With the carpet removed, the drivers side floor was in less than ideal condition.


The Passenger side had been wet in the past but was in much better condition - in comparison.


This current leak was traced back to the cruise control wiring that had been moved when the engine was removed. The wiring exited the large grommet in the DS firewall and traveled upwards. When it rained, water would travel under the bonnet and pool on a small ledge that part of the cruise control wiring came into contact with. The water would the track down the split tube, through the firewall and under the carpet. With the water leak solved and the carpet removed, it was an ideal time to give the interior a long over due clean and finally do something about improving the thermal and sound absorbing qualities for future adventures.

 

[guzzla]

My long term plan is to give the interior a full re-trim so, in the meantime, I figured I'd see how well the original carpet would come up with a decent clean.

The dirty part is the drivers side and the PS had already received a blast with the hose which wasn't much better. As it was hosed, you could see the water turning to mud as it blasted into the carpet.


To get it this clean, the carpet got a several solid blasts with the hose, followed by a soaking of 2 cups of laundry powder diluted in a 10l bucket of boiling hot water. With the solution soaked into every fibre, I agitated it by shuffling my bare feet all over it for about 15min. I then hung it over a couple of saw-stools to rinse it and left to dry for a few days. It hasn't come up like new but, compared to what I started with, it looks pretty damn good after 14yrs of abuse.

 

[guzzla]

Back to the muddy interior, it was time to decide the best plan of attack. Previous research had shown there was some great thermal and sound insulation products in the US, but the cost of getting them shipped here was ridiculous at best. Because the DS was in such poor condition, I decided it was best if the factory sound deadening was removed for two reasons: 1) I wanted to make sure there was nothing more sinister underneath and, 2) it was so dirty and damaged, I wanted to make sure the thermal barriers I wanted to install had a good surface to stick to.

This is a pretty good demonstration of just how hot the floor pan gets. Here is a 5c piece that had melted into the bitumen based sealer. I found a total of $6.05 entombed in bitumen.


Removing the factory sound deadener was a rather time consuming task and best done with several breaks in-between if you wish to avoid self inflicted harm :twisted: . To fully prep the DS floor pan and under the seat took about 5hrs. I found covering small sections at a time with a bag of ice for 10min, hardened the bitumen to make removal easier. A 1in chisel and a 2in paint scraper were the weapons of choice, along with petrol and a rags to disolve and remove any residual bits n pieces. I also filled the metal rib that runs across the middle of the floor with Fullers filler foam to further reduce heat and noise transfer. Note, this stuff is rated up to 90degC and many other brands are not.


Here, the interior is almost ready to begin the installation of the heat and sound barrier. The remaining factory sound insulation was cleaned with a petrol soaked rag and a wire brush to remove all traces of dirt and underlay. The filler foam was left to dry over night before being trimmed off.


Silvershield is an Ormaniod product that is a bitumen based paint mixed with fine aluminum particles. This combination makes for a great metal sealer, rust inhibitor and water proofer, while the the aluminum particles seal the bitumen from leaching through and also acts as a reflective heat barrier.


With 1L and 2 liberal coats, this was the end result of stage 1

 

[guzzla]

After leaving the Silvershield to dry for a few days, I spent some time cleaning out the dried mud in the floor cavities where the body mount bolts are. After a soaking in degreaser and boiling water, followed by a vacuum clean, 4 of the 6 mounting points between the firewall and the back of the rear doors are all clear. However, the mounting points at the back of the front seats are formed with a steel rib that runs under the floor and tapers into the sills. Where these ribs taper down to the sills, they seem to be packed solid with dirt which is blocking the drain holes. I had to give them a blast with the hose to clear them out and figured while I was at it, I'd do the same to all the others as well. It was a good call as even more crap came out.

I'm probably stating the obvious, but removing the bitumen layer from the DS floor pan and under the seat was something I regretted starting about 2min later, but it was well past it's use-by date and needed to come out. I also figured it was going to be a long time before this opportunity presented itself again and it had been something I'd wanted to do for a while now.

The great thing about the Silvershield is that it's basically the only product that can be painted over bitumen without the bitumen leeching through - this is due to the aluminum flakes, apparently. I'm also relying on this product to provide a sound surface for stage 2 to bond to so I went the extra mile with surface prep. And, yes, it really is that bright silver colour

Costs so far is $54 (made up of 1 can of Fullers Filler Foam @ $24 and 1LT Silvershield Paint @ $30)

 

[guzzla]

The 2nd stage involved installing 2-3 layers of a vibration dampening material to decrease resonance of the metal floor. In a perfect world I would have liked to use something like Dynamat sound deadener that's specifically designed for the job but, at close to $1000 for the amount I required, it was way out of my budget. (The shipping costs to Australia were the deal breaker)

Enter a product called Flashtac, which is a sticky, tar based, aluminum backed roof flashing material. It is about 1.5mm thick and comes in various widths from 50mm up to 400mm. I used a 10m x 200mm roll and a 10m x 100mm roll for a total cost of about $50.


Starting with the foot-well, using a Stanley knife, I cut lengths of about 600mm, and starting at one end laid each piece into position and shaped it to the contours of the floor using my fingers and the end of a hammer. It's pretty easy to mold and is made a bit easier if the roll is left in the sun. But be careful, as this stuff sticks real good and is reluctant to be removed if you stuff up. Since this stuff is pressure sensitive, I tapped it all down using a rubber mallet. I also took care to ensure the joins had about a 25mm over lap and the over laps were stepped in such a way to allow any water to flow smoothly towards the gutter. Basically, if you start your first piece running along the edge of the gutter drain inside the door and work towards the centre, you'll be on a winner. Once all entire floor had 1 layer, I then went over it again with a 2nd layer and put a 3rd later in in critical areas such as both foot-well and gearbox tunnel. I used up both rolls without needing more.

 

[guzzla]

The 3rd and final phase was the installation of some decent underlay. I can't remember the name of it, but it's a premium carpet underlay and is about 16mm thick. It comes on a roll 2m wide and I got a piece 3m long for a total of $60 from my local Carpet Court. Because this stuff doesn't mold to contours too well, I cut it into 4 section; 1) under the seats and towards the rear, 2) over the transmission tunnel, 3&4) passenger and drivers foot wells. Each section was cut roughly to size and then trimmed to fit and notching out around brackets, seat mounts and other obstacles. A sharp Stanley blade works best. Once it was all ready, I applied dabs of polyurethane adhesive underneath, mostly on corners and ridges where I wanted it to mould to, and then positioned a few bricks to hold it in place over night.


Here it is all done and ready for carpet.


And finally, the carpet I cleaned a while ago goes back in.


While I was at it, I figured it was a good time to get the rest of the interior a bit neater, so I removed the seat belts and soaked them in hot water with washing machine powder. As you can see by the look of the water, they were pretty filthy, so with a few agitations and a good rinse, they were hung out to dry. I used compressed air to get rid of most the water and dry out the internal workings of the seat belt mechanism. I don't have a pic of them all clean but they came up like new and seem to work much smoother now.

 

[thestunts]

Sweet !
Good job cleaning all the crap up ....

P.S. Didn't think of the seatbelt cleaning, I may have to do that. Thanks for that tip !

 

[Walking Eagle]

Solid work!

 

[sledge916]

nice!!!! So is it less noisy now inside, cooler ????

Sethro

 

[Torquey]

Nice work. I just used a similar material in the rear but have not done the front yet. How was the effect on sound deadening? Did you do the doors?

 

[Wheelingnoob]

Would like to know as well, I have my doors all apart now so it's the right time to get started. I also plan to pull up the carpets to presure wash and clean well. Would be a perfect time to do the floors.

 

[frankenyota]

Old post, but Hey guzzla were you happy with the flashtac? Did it make a difference with noise and heat

 

[LandCruiserPhil]

Its been about six years.....

 

[1973Guppie]

The 3rd and final phase was the installation of some decent underlay. I can't remember the name of it, but it's a premium carpet underlay and is about 16mm thick. It comes on a roll 2m wide and I got a piece 3m long for a total of $60 from my local Carpet Court. Because this stuff doesn't mold to contours too well, I cut it into 4 section; 1) under the seats and towards the rear, 2) over the transmission tunnel, 3&4) passenger and drivers foot wells. Each section was cut roughly to size and then trimmed to fit and notching out around brackets, seat mounts and other obstacles. A sharp Stanley blade works best. Once it was all ready, I applied dabs of polyurethane adhesive underneath, mostly on corners and ridges where I wanted it to mould to, and then positioned a few bricks to hold it in place over night.


Here it is all done and ready for carpet.


And finally, the carpet I cleaned a while ago goes back in.


While I was at it, I figured it was a good time to get the rest of the interior a bit neater, so I removed the seat belts and soaked them in hot water with washing machine powder. As you can see by the look of the water, they were pretty filthy, so with a few agitations and a good rinse, they were hung out to dry. I used compressed air to get rid of most the water and dry out the internal workings of the seat belt mechanism. I don't have a pic of them all clean but they came up like new and seem to work much smoother now.

nice, I gotta do this, any problems with soaking the whole retraction unit?