Noise reduction for my M998

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Kurtshalftrack
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Noise reduction for my M998

Post by Kurtshalftrack » Mon Sep 29, 2008 11:01 am

Trying to keep the wife onboard with my M998, noise reduction seems to be the complaint dejure this week. I have not cutomized this USMC M998 at all and want to keep it as "original as possible," having said that, I am considering Rhino lining some portions of the body inside the passenger compartment. Any thoughts on this? what other methods are being used out there to quiet it down.

Thanks,

Kurt
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1943 M3 Halftrack
1952 M37
1984 M998
M100
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mark m uk
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Post by mark m uk » Mon Sep 29, 2008 11:20 am

Hey Kurt,
Take a peek back a few threads to one " Shake rattle and roll",
think it is on page 3 now. Some very good information and tips from the guys here about noise suppression methods.

I notice you have a halftrack - me too, what the heck are you concerned with noise in the humvee for, after a trip in my track I am so deaf the humvee sounds like a fly fart.

Best, Regards Mark.

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Post by Action » Mon Sep 29, 2008 1:19 pm

If you opt for spray in bedlining, it can be done smooth.

I personally hate the rough look of the normal bed liner.

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Post by hummer4x4guy » Mon Sep 29, 2008 2:54 pm

A few things off the top of my head that ya should check

The seal around the dog house should be in good shape and all 6 of the connectors that hold it down should be tight. I believe this is where a lot of sound comes from.
make sure your injectors are clean and the IP is set correctly. if Its to far to the driver side it will be louder by nature.
another area is the hood I believe that the area nearest the windshield is the best area to play with sound proofing. I recall one winter when i had a foot of snow on the hood the truck was amazingly quiet that day...as the snow blew off..I could tell it was getting louder.
make sure ya have the 3rd strap around your air filter housing.

Get a set of headphones that cut out noise and have built in radios.
Joel
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1987 2 door M998
2001 M1102

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Post by dunsbr » Tue Sep 30, 2008 3:02 am

Hi Kurt,

I could write volumes on this :D

As Joel has said, the first thing is to ensure that all holes in the firewall are sealed.
Check all seals and grommets (the steering column hole is a favourite)

Fit some rubber between the hydraulic fan valve and the body and clamp to stop the annoying hiss.

Make sure you have the rubber coated plastic air duct that connects to the manifold.

Fit the rubber DWF elbow between the airbox and the mushroom cap.

Get the Arctic insulation pad for the top of the trans tunnel from My Humvee.

Insulate under the trans tunnel with Dynamat and anything else you can find.
(See this post: http://www.g503.com/forums/viewtopic.ph ... c&start=30 to see what I did... :roll: )

Install dynamat under the hood to reduce diesel clatter noise.

Fit new hood snubbers and dog bones to the hood to eliminate the squeaks.

Spray inside the cabin with smooth green Rhinoliner.

Fit Supplemental armoured doors or soft doors to reduce squeaks and rattles.

Fit A/C so you can drive with the windows up.

And MOST IMPORTANTLY, fit a 4l80e 4 speed transmission! 8)

I don't think I missed anything. When you are finished it will still look military but be as quiet as a civvy Hummer!

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Post by hummer4x4guy » Tue Sep 30, 2008 5:04 am

Brad
This is the first I have heard about the arctic insulation pad for the trans tunnel. This go inside the truck or on the bottom?
Got pics?


Joel
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Post by dunsbr » Tue Sep 30, 2008 5:18 am

Hi Joel,

It goes inside and is made from the same stuff the floor mats are made from.


I'll see if I can find a pic of inside my truck that shows it.

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

hummer4x4guy
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Post by hummer4x4guy » Tue Sep 30, 2008 5:23 am

Thanks Brad I look fwd to seeing this.
Joel
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1987 2 door M998
2001 M1102

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Post by dunsbr » Tue Sep 30, 2008 5:28 am

Not the best pics, but you can see it on top of the tunnel behind the radio tray...

Image

Image

You can see the edge of the mat near the shifter in this pic:

Image

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

hummer4x4guy
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Post by hummer4x4guy » Tue Sep 30, 2008 5:33 am

Brad
Is this just a regular mat you need to custom cut or is it precut just for this application?
Joel
1987 2 door M998
2001 M1102

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Post by dunsbr » Tue Sep 30, 2008 5:40 am

Joel it's a standard HMMWV part.

It's available with or without a cut out for the gunners platform.
Paul Moeller has piles of them.
~$125ea IIRC

I had to modify it for the RHD shifter and radio tray location.

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

hummer4x4guy
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Post by hummer4x4guy » Tue Sep 30, 2008 8:06 am

Grassy ass Amigo!
Joel
1987 2 door M998
2001 M1102

Kurtshalftrack
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Noise issue

Post by Kurtshalftrack » Tue Sep 30, 2008 11:32 am

All thanks for the tips, I will begin the quieting process one itme at a time. As for the Halftrack, yes it is much louder, but at 2 miles a gallon, I am not in it nearly as much. Parades mostly. Thanks all.
Kurt
1943 M3 Halftrack
1952 M37
1984 M998
M100
America is still the greatest country on earth...don't give up the fight!


San Diego, CA


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