LMTV Upgrades

[kenet3621]

Here is a photo of what I am calling the "winch instruction plate". Sorry I don't know the official name for it.

 

[Lmtv772]

Here is a photo of what I am calling the "winch instruction plate". Sorry I don't know the official name for it.

View attachment 605457

I could maybe use that.

 

[kenet3621]

As those of you who have ridden in an LMTV know the loud engine noises can make conversation with your passenger difficult or impossible (one of the reasons my wife will not going riding in the truck)!

Not very scientific but my sound meter application showed the dB level at idle:



I am installing a sound deadener and heat reducing mat. I anticipate a sound reduction of about 10-15 dB. I don't know what the heat reduction will be but I know in hot weather the bare floorboard was very warm to the touch after a 2 hour highway excursion.

I removed the seats and existing mat and then thoroughly cleaned the floor panels.

Before cleaning:



I ran out of material but have ordered more.
The install is very simple and I used a heat gun to "melt" the backing to the floor.

Here is the installed product on the "hump":



More updates once I complete the project (hopefully by next week).

 

[Pointman0853]

I just finished installing about 40sq/ft of sound mat in my LMTV cab. I did all of the interior panels and the roof. With the cab lifted, I did the entire bottom and the center section up to the air intake vent. You can actually carry on a conversation in this thing now. Stereo to follow..

Pointman

 

[kenet3621]

I finished the sound deadener / heat reducing mat in the cab. I can say it made a very positive difference!

I did not take heat readings but I did make sound readings and here are before and after readings with the engine running at idle.

Before:


After:


We went for a drive and were able to have a conversation without needing ear protection or yelling at each other across the cab!

 

[tennmogger]

Kenet, I hope my project is as successful! I'm using Dynamat Extreme. The big sheet of plastic on the back wall is now laminated on the backside with 3/8" thick sleeping mat.

Is that sound meter an app on a smart phone? Neat!

How are you guys covering the ceiling? Build a headliner? What did you use?

 

[kenet3621]

Sound Meter is an Android app. I use the one by Smart Tools (there are several others but this one is easy to use and calibrate).

I used GTMAT 80 mil Ultra Sound Deadener (from eBay). It took 40 square feet to do just the floor.

Nothing has been done to the ceiling. I am still thinking I might engineer a way to easily open and close the roof hatch (probably project number 99 out of 100!)

I like your idea of insulating the back wall. That might be another project (maybe 10 out of 100!). Thanks for the idea.

 

[tennmogger]

In case anyone else is doing this, the package of Dynamat was 36 sq ft and I ran out. 36 sq ft covered the floors under the seats (completely from front to back including floorboards) and the top surface of the hump. Still wanting to put some pieces on the back wall of the cab, inside the doors, inside the compartments under the side windows, and bottom of the roof. Looks like another 36 sq ft might do that.

Another issue found when cleaning the cab is that the floor is double layer in many places. My truck was full of sand. Obviously sand is a rust magnet so cleaning this 'subfloor' is very important. I am leaving the floor holes open for that purpose. A water hose cleans the void space well.

The original rubber plugs seal the holes in both the layers. I have not found anything like them. Picture attached. Don't laugh but the only thing that resembles that shape is a rubber nipple from a milking machine, and those are too large and too long, but you get the idea

 

[Oxyacetylene]

In case anyone else is doing this, the package of Dynamat was 36 sq ft and I ran out. 36 sq ft covered the floors under the seats (completely from front to back including floorboards) and the top surface of the hump. Still wanting to put some pieces on the back wall of the cab, inside the doors, inside the compartments under the side windows, and bottom of the roof. Looks like another 36 sq ft might do that.

Another issue found when cleaning the cab is that the floor is double layer in many places. My truck was full of sand. Obviously sand is a rust magnet so cleaning this 'subfloor' is very important. I am leaving the floor holes open for that purpose. A water hose cleans the void space well.

The original rubber plugs seal the holes in both the layers. I have not found anything like them. Picture attached. Don't laugh but the only thing that resembles that shape is a rubber nipple from a milking machine, and those are too large and too long, but you get the idea

On some of the early trucks the military applied some sort of sealant type stuff that kind of resembles roll-on bed liner. Mine had it applied to the whole floor. Underneath the driver's side storage box that sealant material is cracked and buckled. I can't tell whether the top layer of sheet metal was that badly damaged from rust, or if it's just that sealant that is all cracked up. Either way I tried to seal all of that up with ultra grey silicone before I put the storage box back in. The cab of my truck had a lot of sand/silt that was very fine, maybe like river silt or something. It took lots of scraping, brushing, vacuuming to get that stuff out. So my thinking is the cab floor probably rusted from water getting into the cab. I would advise anyone who is cleaning up their LMTV to remove the storage box(es), seats, and rubber floor mats to inspect the cab floor.

Also, the newer style floor mat section that goes over the center hump has foam insulation backing and has slits cut for the seat belts so you can install and remove it without unbolting the seat belts. Not sure if my older mat has no foam, or if it is just that worn out. If your mat does not have the slits cut into it, I would do this so you can easily pull it back to clean under it if necessary.

 

[tennmogger]

My floorboard has that tough bedliner-type material, and rust underneath. It has been repaired in the past, too, with fiberglass, so the rust started a long time ago. Luckily the floor has not rusted badly since repaired and the fiberglass is solid.

The only way to stop the rust is to remove all that covering to expose the rust. The rust may have propagated from the holes in the floor. I treated the cleaned metal with POR-15, then re-coated it with Wurth's undercoat spray.

Once the floor/cab mats are out, the cab can be raised about 6 inches in the back and the whole cab sprayed out with a hose, letting the water run to the front. Everywhere I put water had a drain hole (once unplugged). If you line the cab with Dynamat, or similar product, be sure to mark the holes, including the little bolt holes for the boxes. That requirement became apparent after I covered the first 3 holes and had to uncover them to find them!

My mat is the older type. Good idea to cut the slits.

 

[Pointman0853]

I've had my 1994 LMTV since the end of December. I have installed nearly two packages of sound mat in the cab and on the bottom. The difference is amazing. I'm planning on a headliner and will use cut panels of styrofoam as insulation. Even with the sound mat, I can feel the heat through the sound mat on the roof panels.

Next, I am looking at a roof top AC unit..

Pointman

 

[Pointman0853]

Check Summit Racing for rubber hole plugs. They were easy to get and they had plenty in stock..

Pointman

 

[tennmogger]

Pointman, thanks for ceiling idea. I am not looking forward to summer heat. This summer will be my first with the LMTV. I have no plan to add A/C.

Maybe I am over-engineering the floor plugs. I would like to duplicate the original plugs that plug both layers, the floor and the subfloor, with one plug. Maybe that is not needed. Summit has lots of plugs, but only single-layer plugs.

The lower holes are not always reachable from below or I'd plug then from the bottom.

 

[DrillerSurplus]

- -

I am leaving the floor holes open for that purpose. A water hose cleans the void space well.

The original rubber plugs seal the holes in both the layers. I have not found anything like them. Picture attached. Don't laugh but the only thing that resembles that shape is a rubber nipple from a milking machine, and those are too large and too long, but you get the idea

Those "plugs" sure look like duck bill check valves which would let any water drain out, but stop water or air from coming back up into the cab.
You often see bigger rubber valves like this on construction or military equipment air cleaners near the air intake to let accumulated dust out. If you squeeze the flat end, they should open up.
As an example, here is a link to some bigger ones on Amazon. AMAZON duck bill valve

 

[DanM7890]

Have you done anything else to your LMTV? I have been following this thread like a hawk because I have a 1081.

 

[Another Ahab]

Those "plugs" sure look like duck bill check valves which would let any water drain out, but stop water or air from coming back up into the cab.
You often see bigger rubber valves like this on construction or military equipment air cleaners near the air intake to let accumulated dust out.

But what activates the "purging"? Unless the valve is pointed down and you physically pinch it now and then:

- You otherwise need some kind of positive air pressure or something don't you?

 

[DanM7890]

But what activates the "purging"? Unless the valve is pointed down and you physically pinch it now and then:

- You otherwise need some kind of positive air pressure or something don't you?

Yes, and that's what the water is doing when it sits behind the "duck bill". A drop of water may not allow it to open but if water did build behind it, it would open. The more water behind it, the more open it becomes.

 

[Pointman0853]

I will be doing both. I have covered my ceiling with sound mat, and will build a headliner in the future. I don't think covering the plastic panels is as evvective, YRMV. My goak was to remove the 'tinniness' of the metal cab bodywork.

I'm now looking at a 24V roof mounted AC unit, so I will hold off drilling any holes in the roof for now.

Pointman

 

[kenet3621]

My latest project was to "fill" the space on the front of the van with a metal sheet. I have been getting 5.61 miles per gallon of fuel. I figured the "hole" in the middle (see BEFORE photo) was catching a lot of air since it had a "roof" over it. I hope I can improve my mileage somewhat by "filling" that space. A piece of 1/8" sheet metal did the trick. Once I get another tank of fuel I should be able to tell if this made any positive difference.

Before photo:


After photo:

 

[mkcoen]

My latest project was to "fill" the space on the front of the van with a metal sheet. I have been getting 5.61 miles per gallon of fuel. I figured the "hole" in the middle (see BEFORE photo) was catching a lot of air since it had a "roof" over it. I hope I can improve my mileage somewhat by "filling" that space. A piece of 1/8" sheet metal did the trick. Once I get another tank of fuel I should be able to tell if this made any positive difference.

Nice clean installation. Hope it helps the mileage.