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Biggest complaint about my C4 Vette

L

LarryBible

Guest
Well I guess I won't make a very good first impression here by going right into a negative, but I love the car except for this:

The exhaust system on these cars is heavy and difficult to get in place such that it doesn't rattle and squeek and make noises and rattles beyond the great sound that comes out the muffler tips.

I even experimented once with a straight pipe set in place of the converter/exhaust assembly monstrosity. The problem with that was that the DynoMax mufflers were too loud without the converter. I suppose they were designed with the converter in mind.

Has anyone ever used any particular mufflers with straight pipes that sounded good but were not too loud?

This exhaust system makes the whole car feel like a rattle trap.

Have a great day,
 

panzer

Member
Joined
Jul 19, 2002
Messages
23
Location
Fairfax Station, VA
Corvette
2001 Black Z06
Heavy exhaust system.....mmmmm.... buy a Z06 which has a titanium exhaust system 41% lighter than steel and it does not rust... :cool
 
C

c4ever

Guest
Hey Larry,

Well it ain't a Benz:L If you know what I mean.
Many members have experimented with success on numerous types of exhaust packages. I run stock to the Cat with Targas in place of stock mufflers. The systen is tight ,no rattles and has a nice rip without modulation in the 1800-2200 rpm range. I would take a close look at brackets and hangers to make sure they're in good shape.
Great to see MB forum member at CACC. It doesn't get better than this site for Bowties.:w

Carlo
(C4B)
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,236
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
LarryBible said:
This exhaust system makes the whole car feel like a rattle trap.

That's not the only thing that rattles and creaks and moans, etc.. The cars, especially C4s, are all noisy inside. After all, it IS a sportscar.

The problem Corvette got itself into was trying to please everybody by quieting it as best they could, but in the process they added a ton of weight. I guess it's true, you can't have your cake and eat it too. ;)

Speaking of insulation/sound-deadener, Hot Rod magazine has an article (actually it's their "Hot Rod Approved" column - a reviews column) on a sound-deadener from Scosche Industries called "Accumat". It's a thick, "visco-elastic", self-adhesive, flame-resistant material that you can stick to any surface to keep it from rattling or drumming.
We've used it extensively in cars and trucks, and it really works.
David Freiburger

There are three different types: AMT045, AMT250 and AMT750. The numbers represent the thickness of 0.045-inch, 0.250-inch and 0.750-inch, with the last two being foam-backed products for use as carpet base or headliner.

The AMT045 sells for around $20 for five 12x12-inch squares, and it's also available at around $16 per 24x27-inch sheet.

_ken :w
 

panzer

Member
Joined
Jul 19, 2002
Messages
23
Location
Fairfax Station, VA
Corvette
2001 Black Z06
For the sake of noise suppression I was going to try using some high grade house type carpet padding undneath the cargo compartment carpet cover. It ought to be cheap or free from a carpet store to get some scrap.
 
L

LarryBible

Guest
As far as noise suppression goes, carpet will do almost nothing. The best noise suppression is lead foil, but it adds too much weight to a sports car, something you want to keep light.

I don't mind exhaust noise, it's the rattling and squeeking that bothers me. The exhaust note is not noise, it's music.

Have a great day,
 

vms4evr

Well-known member
Joined
Jul 18, 2001
Messages
466
Location
Durham, NC
Corvette
2002 Flat Black Z06
Ken,
The Accumat is one of the products Redbob mentioned when I was looking at tuning out the resonance in the cabin. I checked into the AMT250. Good stuff. But very expensive. Like $35/sheet. And you'll need quite a few sheets to fill up the back of that hatchback on the coupe. I figured I would be in about $300+ to do what I needed to do. It is supposed to be one of the best barrier materials out there. It takes a fair bit to tone down low frequency booming from the exhaust.
Graham
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,236
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
I have a friend that works for an Aerospace company here, he has a ZR-1, and he managed to finagle his way into some of the stuff they use in the airplanes to quiet and insulate the cabin. There are two versions of this stuff; one consists of a layer of plastic-type stuff that is fairly thin, very pliable, resistant to tearing, and is adhesive-backed. The other is a layer of the same material, but with an extra layer of some sort of foam (?) and it too is adhesive-backed. Both of the pieces are supposed to do quite well in reducing interior noise levels, but the foam-baked stuff adds heat-resistance as well.

If he ever gets it together where he's got the stuff for sale, I'll be sure to pass the information along. You figure, if it's good enough to quiet jet noise, it should do well for a Corvette don't you think? ;)

_ken :w
 

CorvetteArchives

Well-known member
Joined
Apr 19, 2001
Messages
547
Location
Carbon County, PA
Corvette
1984 Z51 Silver/Gray & as Much SS & CFibre we find
Larry,
Ironicly we added a Borla exhaust to drown out the squeaks and rattles......they are much more "quiet" now :D
:w
 

Redbob

Well-known member
Joined
Dec 5, 2001
Messages
239
Location
Cross Roads, Texas, U.S.
Corvette
'89 dk red coupe
Larry:
Try replacing the exhaust hangers, especially the rubber pieces that the bayonet hangers go into at the rear of the muffler. When these parts wear out, you have a direct sound path into the car, plus the rattles. Softer rubber at the bayonets will also help significantly in reducing exhaust drone.
Also check that no part of the exhaust comes within 3/4" or so of making contact with any part of the chassis.
Those Dyno Max mufflers aren't designed to be "quiet" with the catalytic converter - they aren't designed to be quiet PERIOD! You can try replacing the cat with a resonator - the exhaust system needs a silencer of some sort at that point in the system.

For sound deadeners in the interior, there are three completely different materials intended for three different jobs.
Foam or fiber pads or sheets are intended as sound absorbers; they dissipate noise, but they need to be at least an inch thick to do any good, and thicker is better. Weight is low, though. A great application for absorber is as a hoodblanket; it reduces engine noise before it can pass into the cabin.
Viscous damping sheet, usually at least .050 thick, is used to damp out panel vibrations, much like a shock absorber damps unwanted suspension motion. You'll often find this material inside the doors, on the outer skin, to prevent the ringing noise when a door is slammed. The "bank-vault" sound of a luxury car's door-slam is due to lots of damping sheet on the door skins. This material is also useful if you have annoying floor buzz, but it's not much good as a sound barrier.
The third type of sound-control material is barrier. It keeps airborn sound out. The most important characteristics of a good barrier are that it be heavy - 1.5 lbs or more per square foot (regardless of thickness) - and that it be limp. From this standpoint, lead sheet is pretty perfect, but heavy vinyls or asphaltic materials are also pretty good. Better still is "decoupled barrier" - heavy vinyl or such with a foam rubber backing. This would be applied to the floor foam-side down, so the foam "decouples" the barrier from the floor sheet, enormously increasing its' effectiveness. Any holes in the barrier, however, pretty well nullify its' effectiveness.
Finally, neither barrier nor absorber will do much good at reducing the low-frequency noise coming from the exhaust or intake.
I realize this is a very simplified explanation, but hey, what do you expect for free! :)
Regards,
- R
 
C

CDN88

Guest
The only complaint I have about my C4 is that I DON'T GET TO SPEND ENOUGH TIME IN IT! :Twist :_rock
 
L

LarryBible

Guest
Thanks for all the responses.

The exhaust setup currently on the car is: aftermarket cat "honeycomb" cat, dynomax mufflers and everything else factory. The noise level and tone out the muffler tips is great. My problem is after getting under the car to shake, rattle and roll the whole exhaust system, I can't get it to rattle, but driving it gets squeaks and rattles, serious ones. My rear Y pipe is BEGINNING to rust where it enters the mufflers.

I have run the straight pipes with the DynoMax mufflers before for a short time, (off road, of course<g>) and this set up is way too loud. But, this setup does not rattle at all. Even though it was too loud to hear a rattle, the rattles I experience are felt as much as heard.

I'm tempted to buy some stock mufflers and try them with the straight pipes.

BTW: Since finding this great site, I have been surprised to see not one but two pictures of '88 standard suspension cars like mine. I never before saw any. The six hole wheels are specific to this year and suspension, so not very common. I was very pleased to see these pictures.

Thanks again,
 
Joined
May 29, 2002
Messages
8,652
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
They must have improved the exhaust system greatly by the time the 96 model rolled off the line. My exhaust system doesn't make hardly any noise @ all. But then again, it's led a pretty sheltered life and has very low mileage, only 27K.

The only complaint with my 96's exhaust is they're to quiet/modest, they need that deep throaty engine sound.
 

maxrevs85

Well-known member
Joined
Dec 17, 2001
Messages
709
Location
Eaton Rapids, Mich
Corvette
!985 ,blue coupe, 4+3 Z51
I have the TPIS header system with a gutted cat and the stock rear y-pipe and flowmasters . It is moderate loud and roars at WOT.....

A Corvette with out rattles and loudeness? They exist?

Oh yea I saw this late eighties Vette in my rear view mirror and then he was passing me. I couldnt even hear him. I was in my truck, What a wimp - mobile. :eyerole
 

Edmond

Well-known member
Joined
Aug 1, 2001
Messages
5,218
Location
Louisiana
Corvette
2003 Z06
maxrevs85 said:
A Corvette with out rattles and loudeness? They exist?

Well haven't you heard the majority of C5's?:L Most of their exhaust tones sound pretty wimpy to me.;)
 

chevyaddict

Well-known member
Joined
Jun 12, 2002
Messages
894
Location
Tucson, AZ USA
Corvette
1990 Convertible
Loud is good! Hell, if I wanted quiet I would buy a cadillac. Our 84 has a nice rumble to it but we don't have any problems with "rattling". We have pretty high miles on it too. I feel like I am in a missle or jet when I go down the road - can't ask for anything more then that. :_rock
 

rdgfx3

Well-known member
Joined
Jul 25, 2001
Messages
202
Location
Rowlett,TX.
Corvette
2008 Silver Coupe
Maybe I'm just lucky.

The ONLY rattle or squeak I hear(d) on my 90,was the Targa top.

Fortunately(?) some kids went through our neighborhood with an ax,and whacked several cars.I guess they thought that was fun.They whacked my passenger door several times.Lots of hits on the passenger window(amazingly it didn't break)whacked both my mirrors off,and broke a hand sized hole in my top.

Why was this fortunate?

Because the new top did not rsqueak rattle or make any noise whatsoever.When I replaced my weatherstripping on the doors,I even cured my wind noise problem!

I tell ya what though,when I first came out and saw my Vette had been vandalized,I was one paranoid sono***un.Who in the hell did I **** off?Later the cops told me several cars had been trashed that night.
 

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