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cab rattle

Discussion in 'Chevy Trucks' started by 85w/350, Jun 1, 2001.

  1. 85w/350

    85w/350 Senior Member
    Messages: 190

    Is there a way to smooth the amount of vibration distributed from the motor to the cab when at idle? My truck performs and idles great but I am bothered at times by how much the cab rattles on the inside at idle. Sometimes it feel much more than it should be. Ya know the shakes inside that you feel sitting at rest waiting for the light to turn green. The engine is a fairly new 350(30,000+ miles) I'm just curious if the feel of idle in a fuel injected engine can be reached with a carburated engine.
  2. 75

    75 PlowSite.com Addict
    Messages: 1,382

    Couple of ideas come to mind, 85w/350:

    How much has been done to the engine in terms of "performance upgrades"? Depending on how it's equipped (cam & exhaust are the big items that come to mind) it may not be possible to get back to the "stock" feel at idle. (If the engine's bone stock and in proper tune, a carbureted setup should idle smoothly) Does the cab get the shakes all the time, in a narrow rpm range or just intermittently?

    The other item to check would be the cab cushions - and motor & trans mounts, if they weren't replaced when the engine was installed. If they are getting old/worn/cracked etc, some of the vibration that normally would get absorbed by them could be finding it's way through to the cab - and you!
  3. 85w/350

    85w/350 Senior Member
    Messages: 190

    almost stock

    Its almost stock the main thing is exhaust....2 chamber flowmaster i am not sure what series it is but its made for internal resonation...bugs the SH*T out of me at around 65mph...rattles everythign including my ear drums to death...I am changing to a diff series and a three chamber ASAP...I think i will check the motor mounts...could loose belts do it too?
  4. MTCK

    MTCK Senior Member
    Messages: 346

    With loose belts you'd also notice a lack of performance from the accessories (squeeky power steering, low volts on alt.) and with no huge cam you should be able to get the motor to idle smoothly. I've noticed the same problem with my pair of 2 chamber 40 series (dual 3") flowmasters. The exhaust is very reverbritory at idle, but sounds great at an even cruise. I think on my next truck I'll get a little bit quieter ones, and save the 2 chambers for my hot rods. I bet that's the main part of your problem.

  5. 85w/350

    85w/350 Senior Member
    Messages: 190

    definately got the squeaky power steering belt...MTCK my flow sounds awesome too at idle and at speeds under 65...sounds aggresive when i get into the secondaries but i agree for saving the 2 chambers for street rides...when i run my new exhaust I am thinking about going with 2 1/2inch pipes off the manifolds to two three chambers and out with 2 1/2 inch pipes to 3 1/2 inch echo tips...
  6. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    If it's coming from your exhaust, check all the exhaust hangers. Make sure all the brackets have a section of rubber on them. If you are using steel straps to hang your exhaust, that's half of your problem. The more brackets with rubber, the better.

  7. 85w/350

    85w/350 Senior Member
    Messages: 190

    changed the belts that did alot....chuck i checked the underside and its all rubber hangers...the shop i had my exhaust run at did a great job with it...but being that i dont have a catallic convertor could i not be getting enough back pressure from the muffler alone to the engine causing it to shake a bit more? The backpressure concern is the reason for me going with smaller pipes this time to the muffler. right now its just 1 in from the engine standard 3inch pipe 2 out (2 1/2inch)