|Moderated by: Greg Fletcher|
|We've all seen DynaMat installed over the entire interior of a car with foil facing. We are led to believe that this is the ultimate in sound deadening. Here's a website that disputes that notion:
Heat control is another real issue in the JH. Foil facing on synthetic jute mats is a popular product, but the foil is a conductor unless there is an airspace adjacent to it. This would work great under the car to reflect the heat from the exhaust pipe.
I think following the lead of luxury car makers would be the prudent path to follow. Heat reflectors between the headers and floor boards, judicious use of DynaMat or similar products, thick carpet padding, and tightening any rattling screws and bolts will go a long way towards keeping the JH quiet and cool.
|anecdotal experiences of mine...
A friend bought a new pickup and it definitely had the empty oil can sound from the bed until he had the rhino liner stuff sprayed in back there, after that is was quite a bit quieter. depends on your perspective if you consider it a thick or thin coating, looked to be about 1/8 of an inch thick. I wonder if this would work in the trunk or on the floorboards.
The webpage you linked is correct about tire choice in regards to ambient noise level. My daily driver Challenger RT came with 20 inch Goodyears from the factory on it and they have a square block tread design. They are louder than the all season 17 inch tires that were on my 2005 Durango... heck, they're louder than the 31-10.50 all terrain tires that came on my 2000 Dakota 4x4. Back when I worked for a BF Goodrich dealer, the two quietest tire designs we sold were the BFG Touring T/A, and the original Uniroyal Tigerpaw highway tire.
Header wrap tape does a nice job of eliminating under hood heat and noise, but unless you're using it on stainless pipes, any regular steel exhaust tubing will rust faster unless you spend the extra money for the ceramic coated pipes. I have not tried it on aluminized exhaust pipes, so I can't say for sure if header tape makes aluminized pipes rot faster or not.
I haven't crawled underneath mine yet to do a full inspection of the exhaust, but rubber insulated exhaust hangers block a lot of the vibration from the passenger compartment, in comparison to what can be transferred through solid metal exhaust hangers. A raspy exhaust note behind the car is good, buzzy noises in the driver's seat bad...
If you're going to try to build your own heat reflectors for parts of the exhaust system, the question I have is how do you plan to mount the reflectors? A little bit of bead rolling and bends in the proper places will easily eliminate any oil can vibrations from the reflectors, and I assume you'd be going with stainless steel sheet material to get maximum life from them. Would you mount them with stand off tubes and stainless fastening hardware?
|I'll see what I think when I get 14539 back on the road here. I went with stuff from a company called Second Skin Audio. Similar to DynaMat but a local company. Covered the whole interior of the body. Trans tunnel got the additional foil back padding. Floor has a thin layer of padding also on just the front sections.
Tires I agree have some contribution to the level of noise. Depends on tire compound and tread. Also the road condition and material plays its part. I could drive on rubberized asphalt and the car was very quiet. Drive on old regular asphalt or concrete and you could tell the difference.
I had the headers ceramic coated and am interested in how much of a difference it will make. Never been a fan of the heat tape stuff.
As for the exhaust system, pretty much most of the current thinking is to use rubber isolation mounts. That's what I have to use here for the new exhaust system.
As for a heat shield, the GT had one mounted under the car where the driver sat. It was mounted to the underside with I believe 6 standoffs. Since the GT is gone I thought I might use it on one of the JHs.
Of course, driving the car at speed with the top down and radio going, I don't think we would hear many other noises other than the engine and wind.