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Thread: Clunking noise from front end on bumps

  1. #1
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    Post Clunking noise from front end on bumps

    Hi,

    I've got a 1997 ZJ with 111,000 miles. Ever since I bought it (Last March with 92,000 miles) it's had a clunking sound coming from the front end when going over bumps.

    It seems to happen when the bump only hits one of the wheels. If the bump in the road is wide enough where both wheels hit it at the same time, then there's not much noise (if anything at all).

    However, when the bump only hit one wheel (like most frost heaves here in the northeast) then it makes a loud clunking sound. It will happen with the bump is on either side of the car.

    I took it to a front end shop a while back and they thought it might be a bad sway bar bushing, but they weren't sure.

    Has anyone experienced something similar to this? Any ideas what might be causing it?

    Any help or insight is much appreciated.

    Thanks,
    -Brightdog

  2. #2
    Victim of Circumstance HighDesertZJ's Avatar
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    Post

    Since a search on "clunk" would yield quite a bit, here's an edited quote from Wharfrat:

    Here are the usual culprits in order of probability:

    1) What are your sway bar end links like? The stock ones always clunk (in
    the 96-98 ones at least) and only JKS discos will solve this unless you want
    to buy new sway bar end links for 3/4 the price of the JKS units. My dad
    complains about clunking in his 5.9 and I suggested the JKS discos even
    though he does not wheel the thing.

    2) Track bar--it is tough to get the upper mount as tight as it needs to be
    due to the location of the castle nut. I usually put a box-end wrench on it
    and hit it with a BFH to tighten it (but not too hard ) That problem is
    eliminated with the RE track bar. The lower mount is easy to tighten and
    should be about 65 lbs/ft. (factory spec is 55 I believe).

    3) Control arms--factory specs are rediculous--like 50 for the uppers and
    35 for the lowers. This is wrong if there is any sort of wear at all...The
    uppers should be tightened to 60 or 70 and the lowers should be "bubba
    tight".

    4) Shock mounts--What shocks do you have on it? If you have IAS's, I
    believe they will clunk a little with the BPE's. Mine always rattled until
    I got the OME ones, which actually fit right and ride awesome. To get the
    top mounts tight, put a wrench on the nut and spin the body of the shock
    with your hands.

    5) Steering box where it attaches to the frame. Each of these bolts should
    be about 75 lbs/ft. also.

    The bushings in the control arms will shift. Do they appear a little
    tweaked when you take them out? If so, that is normal. Even my RE ones
    look a little sketchy at the body-side rubber mount. When they are in there
    and tight, there should be NO room for movement though.

    If all of these fail, then look around EVERY component (backside too) for
    places where the dirt is gone and things are "rubbed clean" which would
    indicate contact that is not supposed to be happening. I doubt that this is
    your problem, but every GC is different, especially when you lift it.
    Things could be touching each other under compression, compression while
    turning, etc, that you wouldn't EVER think of just looking underneath while
    it sits in your driveway.

  3. #3
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    Post


    I would add the brake calipers too. Since it seems to only come from one side it would make sense. The rod bore of the caliper gets bigger sometimes over time and could cause it to move around. Not a big deal IMHO.

    HTH,

    Maurice


    ------------------
    Maurice
    '95 ZJ 5.2 V8
    Maurice
    '95 ZJ 5.2 V8 - 2"BB, 31" BFG AT/KO

  4. #4
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    My money is on sway bar links..
    Put your hand on them while someone rocks the car, you can feel the pop in and out...Be carefull not to pinch your fingers!
    MIKE

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  5. #5
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    I would put my money on the end links or the swaybar bushings. I had the same clunk on my 97 for the past 2 years. The dealer said they even replaced my bushings and end links but that didn't work. Just recently I replaced the bushings myself it has taken care of all of the klunks in my front end.

    ------------------
    Jason Buser
    97 ZJ 5.2L, K&N drop-in, Mopar Tow Hooks, Mopar T-Case Skid, Hidden Hitch, Yakima Railriders with Steelhead Bike Mount, Kolak Headlight Harness
    Jason Buser
    97 ZJ 5.2L, K&N drop-in, Mopar Tow Hooks, Mopar T-Case Skid, Hidden Hitch, Yakima Railriders with Steelhead Bike Mount, Kolak Headlight Harness

  6. #6
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    Cool

    you know how to excite me Jason B - i'm all over that first chance

  7. #7
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    Post

    Hey Guys,

    Thanks for all the replies. I think once the weather starts warming up here in the northeast I'll start tinkering with this again.

    Jason, how tough was it changing out the sway bar bushings? It looks like they unbolt from the frame easy enough, but how are they to get off the sway bar itself? And do you recall what you paid for the new ones?

    Thanks,
    -Matt

  8. #8
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    Matt, It's not hard at all. Probably a 30-45 min. job tops. Just take out the 2 bolts holding the bracket on on each side and then just pull the bushing off. The bushings are split on one side so they just slip over the bar to put them on or take off. I think the dealer charged about $11 per bushing. Is what's funny is that they price them per bushing but they don't sell them individually only in pairs. Just to let you know how much you save by doing it yourself, the dealer wanted about $130 to do this job.

    ------------------
    Jason Buser
    97 ZJ 5.2L, K&N drop-in, Mopar Tow Hooks, Mopar T-Case Skid, Hidden Hitch, Yakima Railriders with Steelhead Bike Mount, Kolak Headlight Harness
    Jason Buser
    97 ZJ 5.2L, K&N drop-in, Mopar Tow Hooks, Mopar T-Case Skid, Hidden Hitch, Yakima Railriders with Steelhead Bike Mount, Kolak Headlight Harness

  9. #9
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    Can the noise source be eliminated if you remove the links (test)? If it does, then that would definitely be the problem...

    I've also read on here about bad motor mounts causing a clunk type noise...I have more of a thud-type clunk on bumps, but it's kinda like yours, where only one side does it (at a time)...

    I'm not sure if it's the mounts though, cause I seem to have other symptoms of bad mounts (clunk in shift, lower speeds; floor vibes under light accel.; rough idle (feels like))...

    It would be interesting if it is the mounts...can anybody elaborate?

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  10. #10
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    Cool

    the dealer replaced end links and sway bar bushings and suddenly frontend is quiet and smooth - i'm in heaven. thanks guys for heads up on this!

  11. #11
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    Talking

    I just thought I would let you all know that I replaced the swaybar bushings this morning.

    And I'm happy to report that the clunking noise is GONE!!

    Thank you all so much. I can enjoy driving my ZJ again now without wondering what's causing that $%^& clunk!!!

    -Matt

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