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Thread: knocking when transitioning on/off light throttle

  1. #1
    Join Date
    Sep 2013
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    knocking when transitioning on/off light throttle

    Hi all,
    I'm getting a front end knock. It happens on dead flat road, happens mostly in 1st but happens also 2nd 3rd etc if your going a little too slow for the gear. If I'm coasting and then just give it the slightest throttle it will knock and then if I back off the throttle again it will knock. Also happens if I take off normally from standstill.
    It's not the bar hitting the steering arm mid cornering problem as there's no feedback through the wheel.. Its also not brake related as I'm not on or off the anchors when its happening. It crossed my mind that it could be the rear engine mount, but it happens when transitioning from coasting/zero throttle to just a tiny little application of throttle, so I didn't think the engine could be moving around too much.
    Feels almost like backlash is being taken up and then out when it happens. I say this because if I'm coasting down a slight gradient with ever so slight engine braking happening its not as easy to replicate - its really pronounced on the flat. And if I'm flowing along nicely its not there either - its a light throttle transition thing.
    checked the anti roll bar mounts and droplinks and exhaust hangers where it turns around the bottom of the fire wall and for any evidence of contact between anything and nothing obvious is there. any clues?

    thanks

    sam
    Last edited by sambb; 25-09-2013 at 10:49 PM.

  2. #2
    Join Date
    Jan 2013
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    Brisbane, QLD.
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    Check all your engine mounts mate, don't be scared to go at them gently with a pry bar and check them for cracks that turn into gaping holes when moved with a prybar.

  3. #3
    Join Date
    Dec 2012
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    Sydney,NSW
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    Lower control arm bushes front ? Too common

  4. #4
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    will do. there's only the two either side and the dogbone isn't there? I don't know though - the cars only done 28k km;s and I've driven mostly sedately since I bought it due to dried up cracked original tyres and a split right LCA rear bush. Could a 28k km engine mount be that knackered that it would click like that going from zero throttle to hardly any? Then again the LCA bush is turd!

  5. #5
    Join Date
    Sep 2013
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    nsw
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    I'll have a sqiz at the front LCA bushes. I had doubted even the rear LCA bush (which is splitting) because I haven't noticed the same sound when I've got the chassis moving around. I'll probably just do them as a matter of course when I address the rear LCA bushes.

    thanks

  6. #6
    Join Date
    Sep 2013
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    nsw
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    Yeah if I grab hold of the inlet manifold and rock the engine front to back I can replicate the noise. The top driver side mount looks ok although with heaps of movement in it, but how the hell do you get to the passenger side gearbox mount - is the only way of getting to it by going in from the top and removing intake ducts etc etc etc or do you need to remove the radiator?

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