Flowmaster Cat Back Exhaust
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Instructor
Joined: Sep 2002
Posts: 105
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From: Wixom MI
Flowmaster Exhaust Making Terrible Noise
I recently bought a flowmaster force 2 cat back system and took it to the local muffler shop to get installed. It sounds great except for this horrible vibration/grinding noise it makes mostly btwn 1700-2000 rpms or if i really get on it theres the same noise. I understand there will be some interior resonance but this is different. It sounds terrible and rattles the floor. I took a look underneath the car in my garage and it seems like the clamps are vibrating against the cross members. There is about 1/8-1/4" of clearance from the clamps to the cross members and I'm guessing when its around 1700-2000 rpm the exhuast starts bouncing enough to hit the cross members. I can handle the noise but it doesnt sound good at all, I'm worried it could cause some sort of damage. Any thoughts?
[Modified by 40th, 11:59 PM 9/9/2002]
[Modified by 40th, 12:00 AM 9/10/2002]
[Modified by 40th, 11:59 PM 9/9/2002]
[Modified by 40th, 12:00 AM 9/10/2002]
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Joined: Aug 2002
Posts: 92
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From: Salt lake City Utah
Re: Flowmaster Exhaust Making Terrible Noise (40th)
I test drove a 92 with flowmasters, it was soo loud I could here my self think. my daughter went with me she plugged her ears the whole time :lol: I dont know if the vibration would damage anything and I didnt want to find out so I bought one with stock exhaust.
Intermediate
Joined: Sep 2002
Posts: 26
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From: Sarasota Fl
Re: Flowmaster Exhaust Making Terrible Noise (40th)
Hey 40th,
I just put Force 2s on my '86 Convert and they weren't any louder than the stocks I pulled off. Man was I bummed. But it got me to thinking, my car has been running sluggish and from around 50 on the school buses can give me a run, I'm thinking clogged cat. Does yours have the cat and pre-cats? Gotta get more sound from mine......
I just put Force 2s on my '86 Convert and they weren't any louder than the stocks I pulled off. Man was I bummed. But it got me to thinking, my car has been running sluggish and from around 50 on the school buses can give me a run, I'm thinking clogged cat. Does yours have the cat and pre-cats? Gotta get more sound from mine......
Melting Slicks
Joined: Apr 2001
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Re: Flowmaster Exhaust Making Terrible Noise ('86PaceCar)
I have flowmaster 2-chamber mufflers on my car and non-car oriented people ALWAYS complain about how loud the car is. "Is it supposed to be that loud?" and so forth. It does have a lot of resonance between 1700-2000rpm, but I just shift around it. I love the sound. Hope you do too.
Melting Slicks
Joined: Sep 2000
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From: PITTSBURGH PA
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Re: Flowmaster Exhaust Making Terrible Noise (stormy652)
i am with you stormy652
(quote non-car oriented people ALWAYS complain about how loud the car is) avette is supposed to make some rumble if you want quiet buy a mini van :D
(quote non-car oriented people ALWAYS complain about how loud the car is) avette is supposed to make some rumble if you want quiet buy a mini van :D
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Joined: Mar 2000
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From: Springfield VA
Re: Flowmaster Exhaust Making Terrible Noise (40th)
I recently bought a flowmaster force 2 cat back system and took it to the local muffler shop to get installed. It sounds great except for this horrible vibration/grinding noise it makes mostly btwn 1700-2000 rpms or if i really get on it theres the same noise. I understand there will be some interior resonance but this is different. Any thoughts?
You will like the Force IIs as soon as they are installed right.
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Instructor
Joined: Sep 2002
Posts: 105
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From: Wixom MI
Re: Flowmaster Exhaust Making Terrible Noise (stormy652)
I defnitely think the louder the better but this is not a rumble its a grinding noise from underneath that is horrible sounding. I think im going to take it back and have it reinstalled.
Race Director
Joined: Apr 2000
Posts: 15,344
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From: Texas
Re: Flowmaster Exhaust Making Terrible Noise (40th)
It sounds like they didn't properly install (or install at all) the hardware that suspends the exhaust. It's hard to see, but if you look at the pic below of my old exhaust, you can just barely see a couple bolts in front of the resonator. Each "clip" is attached to a spring. There are four of these total. If they failed to install them properly, the exhaust will bounce/vibrate.
http://www.grandsportregistry.com/te...s/oldexhlo.jpg
For those with L98 C4s, the LT1/4/5 Flowmaster exhaust system is different because of the cat configuration and center resonator. Also, the LT1/4/5 Force 2 systems use 3-chamber mufflers. The discontinued "American Thunder" cat-back system used the 2-chamber mufflers. I had 2-chambers on my '90 (no pre-cats, high flow main cat) and although it sounded great, it was mind numbingly LOUD.
Here's what the LT1/4/5 system looks like.... http://www.grandsportregistry.com/te...s/newflowm.jpg
The only difference between the LT1/4 & LT5 setup is the attachment to the passenger side cat. teh LT1/4 uses a slip fit, the LT5 uses a flange
:cheers:
Jim Mason
'96 Grand Sport #007
http://www.grandsportregistry.com/te...s/oldexhlo.jpg
For those with L98 C4s, the LT1/4/5 Flowmaster exhaust system is different because of the cat configuration and center resonator. Also, the LT1/4/5 Force 2 systems use 3-chamber mufflers. The discontinued "American Thunder" cat-back system used the 2-chamber mufflers. I had 2-chambers on my '90 (no pre-cats, high flow main cat) and although it sounded great, it was mind numbingly LOUD.
Here's what the LT1/4/5 system looks like.... http://www.grandsportregistry.com/te...s/newflowm.jpg
The only difference between the LT1/4 & LT5 setup is the attachment to the passenger side cat. teh LT1/4 uses a slip fit, the LT5 uses a flange
:cheers:
Jim Mason
'96 Grand Sport #007
Race Director
Joined: May 2001
Posts: 14,165
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Re: Flowmaster Exhaust Making Terrible Noise (40th)
I bought my exhaust a little differently than most. I just bought 2 flowmaster mufflers and had the shop install them in place of the stockers, nothing forward of the mufflers was changed at all.
Later when I got the headers I had to modify the cat back again. I took it back to the same shop and had the guy replace the center resonator with a custom made X-pipe. Now the only remaining pieces of my stock exhaust are the pipes on either side that went from the resonator to the mufflers. Oh, the tips are stock too.
In any case it's LOUD, but it doesn't grind on anything. Something is wrong there, take it back and have them do it right. You should be able to see where the pipe are rubbing.
Later when I got the headers I had to modify the cat back again. I took it back to the same shop and had the guy replace the center resonator with a custom made X-pipe. Now the only remaining pieces of my stock exhaust are the pipes on either side that went from the resonator to the mufflers. Oh, the tips are stock too.
In any case it's LOUD, but it doesn't grind on anything. Something is wrong there, take it back and have them do it right. You should be able to see where the pipe are rubbing.
Drifting
Joined: Jun 2002
Posts: 1,406
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From: York PA
Re: Flowmaster Exhaust Making Terrible Noise (96GS#007)
I bought the Flowmaster Premium Mufflers from Mid-America for my 90 Corvette. They're being installed this evening. It has me wondering which series they really are. I'm guessing they are the 50 Delta series. The description doesn't actually say what series they are. Can anyone confirm this? Who has purchased these and how do you like them? The wait is killing me!! I get my car back later tonight.
[Modified by fast90, 9:00 AM 9/10/2002]
[Modified by fast90, 9:00 AM 9/10/2002]
Racer
Joined: Oct 2001
Posts: 274
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From: Bradenton Fl
Re: Flowmaster Exhaust Making Terrible Noise (fast90)
I have the Flowmaster Force 2 cat-back that zip has in their catalog I don't know what mufflers come with it, but I haven't had any problems with it and it wasn't too loud but now that the cat is gutted it sounds great to me, my girlfriend thinks its to loud.
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Instructor
Joined: Sep 2002
Posts: 105
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From: Wixom MI
Re: Flowmaster Exhaust Making Terrible Noise (daddydahlin)
I wanted to gut the main cat as well. I was told by a friend that it would screw up the o2 sensors readings and the car wouldnt run right? Daddydahlin, do you have any problem with yours or was that a false statement or is it different for a 93 instead of an 86?