Guys, these Hooker Aero mufflers on my stock LT1 sound good at idle and open throttle, but from 2000-2500 rpm send a killer vibration through the interior, and me. The bolt/weld of the mufflers seems very solid, including some rubber dampners. I heard a suggestion that "resonance is a quality of high performance mufflers." Given advice that a crossover between the exhausts(p.81 Ecklers, apparently) is a potential cure.

Has anybody else used these mufflers or tried a crossover cure - can sending these vibrations into each other really cancel them out or am I throwing money away on another substandard exhaust mod?

Thanks. :chevy


[Modified by c4dailydriver, 4:10 AM 12/6/2001]

 

Here's the deal if these have two outlet pipes on each muffler like most vettes. I learned about this from Phil lt401. there is a plumbing thingy called a pipe plug. It is two steel washers with a rubber donut or washer in the middle, a bolt going thru and a wing nut that squeezes the washers together, expands the rubber and seals the pipe. trim the washers to fit inside one outlet pipe on each muff, put one in a pipe on each side, turn the wing nut, it seals off the outlet. YOU WILL NOT BELIEVE THE DIFFERENCE. I had cheapo muffs that sounded awesome but actually made the wife and me sick on trips the resonance was so bad. I saw no noticeable SOTP difference in performance but have not tried it at the strip. The only problem is I could only find 2 inch plugs for the cheapos but cannot find 2 1/4 plugs for the flowmasters I run now. I stuff shop rags in one pipe on each side for trips. The fms are not nearly as bad as the cheapos but bad enough on a long trip to use this mod. I think I may page Phil to see if he knows where to get different sizes. You can try this with shop rags. Let us know if it works for you
Harold

 

shop rags in the exhaust sounds like a fire waiting to happen, especially on a long trip!

 

I have the Aero Chamber Mufflers too. I put sound deadening material inside the cargo area and fiberglass insulation between the spare tire and the chassis. It helped allot.

 

Man, that's a great description and I can actually visualize the pipe plug application. Could you ballpark the amount by which you were able to reduce that dam drone effect? Did the plug cut it down by 50%? 75%? Please o Please tell me 95-100%.

What's also interesting about your description is that, since I haven't swapped out the whole length of the exhaust, it doesn't make sense to put a crossover/connection in mid-exhaust. The fact that you can nail this vibration down by working on one of the exhaust tips suggests that it's vibration in the tips themselves?? Is it because these tips are longer and actually wider than others(a bragging point in the ads in Ecklers) that they vibrate more and act like the bells that made Quasimodo goofy? Since the tips are only stainless near their ends, maybe I can secure the two outlets together(an outlet crossover??some kind of hose clamp going around both?) and even to the bracket above them to reduce/elim the vibration? Hmmmm.... a little wire, some JB weld, and a six pack. Wait a minute - vette's balanced on shaky bricks/firewood while I wait for wheels. I better hold off on this experiment. Let me know if you think I'm way off base. It would kill me to have to take these off! Hey, if we figure this out, we could patent the doohicky outlet crossover and retire.

Geno- I definitely need to look into securing the spare better(it's been two weeks since I had a flat and threw the spare back behind the bumper!)
Tanks. By the way, yer drivin' the C4 I wished I had for a long time. I'll post my pics after new wheels are sorted out.

Thanks guys! :cheers:

 

Sounds like those expandable rubber freeze plugs you can get at any auto parts store. That might be a source for 2 1/4" ones.

 

I have eliminators on my 94 vert. There is a lot less ressonance with the spare tire and carrier removed. With the combination of 4.10 gears and removing the spare my ressonance has been reduced by %80. It's to the point now where I actually like 'em. :)

Jim

 

I do not know about the crossover. The drone in my car was so bad you had to shout to have a conversation. After 50 or 100 miles the car would just wear us out. It was BAD. The plugs eliminated the drone and produced a softer quieter sound. The rags do not heat up in any way. The freeze plugs should work fine if they are the right size.
Harold