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Brand New Custom Exhaust System Question

Discussion in 'GM Powertrain' started by willbradfan, Jul 23, 2011.

  1. willbradfan

    willbradfan Rockstar 100 Posts

    So, I just got my new pacesetter long tube headers installed with a true dual custom exhaust and it hard mounted to the frame. I noticed while driving 70-80mph and if accelerate between those speeds I get a really bad vibration as its coming from the exhaust. Should the exhaust be vibrating like this? this will be my 3rd trip back to the exhaust shop to try to get it fixed right again, i think i am going to tell them to do away with the hard mounting setup as I hate the vibration that comes with it. Has anyone else ever had this problem with a hard mounted exhaust setup?
  2. 99'HEARTBEAT

    99'HEARTBEAT Epic Member Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Sorry but I've not heard of a Vibration, due to the installed of Custom Exhaust System???....:neutral:.....I would agree with you on do away with the hard mount setup.
  3. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    I'm assuming by hard mounting your saying they welded the pipe hangers directly to the frame with no rubber insulators?
    If so yes this could cause vibration, probably cause cracks on the exhaust piping too after a while, theirs no place for the system to flex when the engine torques under load.
    I'm surprised a shop would weld the system in like this, I've honestly only seen one other exhaust welded directly to the frame and it was by a back yard mechanic that had very questionable mechanical skills.
    The rubber insulators between the hanger points and frame are there to stop excess stress and vibration, the system needs to move a little independantly of the frame.
  4. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    X2 what Mike and Tim said.
  5. willbradfan

    willbradfan Rockstar 100 Posts

    My bad, I didn't clarify what I meant by the hard mount. They used a piece of metal that is welded to the pipe and then attached to the frame by rubber mount. The vibration is off and on when I am driving, at times it vibrates a lot and then its gone. Im guessing one of the mounts may be rubbing somewhere?
  6. TELORVEHC

    TELORVEHC Rockstar 4 Years 1000 Posts

    Maybe spray some WD40 on the rubber mount? Also, how old are your rubber exhaust mounts?
  7. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Rubbing once in a while is a possibility, you should be able to find the spot by looking for fretting and galling around the mount points.
    As willbradfan pointed out the isolators could be stiff since their new and not broke in yet and not allowing as much flex as they should.
    Petroleum based lube on rubber parts speeds up deterioration of the rubber, try using a teflon spray or graphite on the isolators where they're attached, the exhaust needs to move at least a little, if it cant move the vibration will be telegraphed right to the drivers seat.
  8. willbradfan

    willbradfan Rockstar 100 Posts

    So i the exhaust shop finally fixed the problem. They said my engine was putting out too much power for their rubber mounting brackets that caused the metal part of the bracket to break the rubber allowing metal on metal vibration. They fixed by using the oem exhaust mounts. I haven't had a problem since :party:

    Now I just have a backflow pressure problem i think...takes a few seconds for the engine get going at first and then it just takes off like nothing happened, this only started happening after the longtube headers and exhaust were installed
    Last edited: Jul 26, 2011
  9. sstoner911

    sstoner911 Epic Member 5+ Years 1000 Posts

    Maybe the Tune needs to be adjusted for the exhaust set up?
  10. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Thats what I'm thinking, sounds like it's stumbling a little.

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