[Cruisin_RC]

Seems my glasspack muffler is just the right frequency of sound to get the body of the old RC vibrating. You can't tell so much while it's running and driving, just that your ears kind of pick up this tone. Once you shut it off, you can really tell, however. The whole rear body rings like a large, low tone bell. It sometimes lasts up to 8 seconds after shutting the engine off. I'm guessing it's the floor over the muffler, and that some dynamat or undercoat may help the situation somewhat. Just plain weird, IMHO. Anybody elase noticed this?,,,,Cruisin

Also planning to stuff the rear 1/4's with home insulation. You can laugh, but's the same thing they used on my 86 Ford conversion van, to quiet it down. Cheap and effective.

 

[m2bueller]

I used rigid foam insulation behind my inner side panels. It cut down the road noise by about 50%.

 

[K.C.]

Did you figure out the source of the vibration? My first guess would be that the exhaust system is mounted too rigidly to the chassis. Sometimes they develop a harmonic vibration. You could try temporarily attaching some weights to the exhaust pipe in different locations to see if the problem changes or goes away. This is sometimes done with prototype or pre-production vehicles to sort out harmonic vibrations. Are all the rubber mounts where they are supposed to be?

 

[Cruisin_RC]

Well, the exhaust is factory, except for the muffler, which is a glasspack. The rest of it is all stock, I can tell by the amount of rust on it. Wish they had figured out the stainless thing earlier, lol.Cruisin

 

[Taz_man440]

My hot-rod did that while I had the duels with hedder mufflers and echo tips.. After I switched to sidepipes, it stopped..Now it rattles the vehicles next to me..LOL