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308 left rear clunk on bumps

Discussion in 'Technical Q&A' started by corse driver, Aug 19, 2004.

  1. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    Hello all. I have recently aquired a very nice red/black '82 308 gtsi. It has 38,000 miles.
    Recently it quickly developed a clunk noise from the left rear while driving over bumps in the road. Only harsher impacts from the road make the noise not undulations or loads under cornering, accelerating, or braking. I checked out the suspension points and they are very solid and have no play. It sincerely feels like it is from the suspension, but I can't figure out what it is.
    There is no play in the wheel bearing and I beleive the CV's to be in good shape. Got any ideas? Anyone have this problem?
     
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  3. Darolls

    Darolls F1 Veteran
    BANNED

    Jul 2, 2003
    6,799
    Full Name:
    Sparky
    It sounds like you know what you're talking about.

    If all else looks good, you may just be bottoming out the shock.

    If that's the case, replace both rear shocks.....or, all four!
     
  4. Skindiver

    Skindiver Karting

    Apr 22, 2004
    203
    JHB SA.
    Full Name:
    Greg
    Check for even the slightest play in the bootlid first.

    Skin
     
  5. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
    Full Name:
    Verell Boaen
    Did 'suspension points' include all of the following bushings:
    - Sway bar end link bushings (2/end)
    - Sway bar mounting bushings
    - Inner a-arm bushings (2/a-arm,4/wheel)
    - Shock bushings (2/shock)

    If all are good, that pretty much points towards a bad shock.
     
  6. Sophia

    Sophia Formula Junior

    Aug 17, 2003
    298
    Dash Point/Federal W
    Full Name:
    Peter Barbin
    There is no play in the wheel bearing and I beleive the CV's to be in good shape. Got any ideas? Anyone have this problem?[/QUOTE]

    Yup...mine did the same. It was the left front in my case. The old Konis were shot. Got a new set, kept the old ones for possible rebuild in the future when new ones are unobtainium...Noise gone. PeterB.
     
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  8. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    How can the koni shock make a clunk? It would have to be an internal noise.

    Does this mean the shock is trash or that it needs dampner fluid?

    I honestly beleive ALL the suspension points are fine and my boot lid is not rattling. I guess I am just amazed that a shock could make a clunk internally.

    Also, when I push up and down on the left rear corner by the bumper, there is less dampning that the right rear corner and the left rear shock make a sound like it is low on fluid.

    I guess I am just curious how it would clunk internally.
     
  9. Sophia

    Sophia Formula Junior

    Aug 17, 2003
    298
    Dash Point/Federal W
    Full Name:
    Peter Barbin
    Reading this is like dejavu with my 30K mi 308...not being an expert on the internals of these shocks however, I can't explain what "fault within" is causing the transmitted noise. I was a BMW mechanic in a "previous life," it doesn't take much of a tolerance exceedance (worn/broken internal & or fluid loss) to produce these types of mystery clunks in suspension components...PeterB.
     
  10. bill308

    bill308 Formula 3
    Silver Subscribed

    May 13, 2001
    1,080
    Windsor, CT
    Full Name:
    Bill Sebestyen
    I had a clunk in the rear that defied diagnosis for 3-weeks. The rear suspension was completely rebuilt about 2-years ago. The clunk occured in 1st gear under high wheel torque conditions. My friend Tim suggested it sounded like motor mounts. Sure enough. The front 2-motor mount bolts had fallen out. The rear two were loose. I replaced the fronts and tightened the rears. I also had to replace the bushings in the troque rod that had taken a beating as a result of the loose/missing motor mount bolts.

    Check your motor mounts and the bushings in your torque rod (rear head to chassis).
     
  11. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,687
    North shore, MA
    Full Name:
    THE Birdman
    My 308 has this same problem. I did a complete rebuild of my rear suspension including rebuilt shocks and new bushings last winter in an attempt to correct it. It did not fix it. I drove another 308 a few months ago that had the *exact* same clunk (I mean, if I closed my eyes, it could have been my car). I have heard that many 308's seem to have this issue.

    I adjusted the engine lid (engine hood) catches as Skindiver suggested so there is zero play. I was definitely getting a tiny clunk from there which is now corrected, but it didn't fix the big clunk. I have a feeling it's an engine mount, allowing the engine to move a little on the larger bumps and whack against something. There are some pretty close tolerances between the engine/exhaust assembly and the other parts of the engine bay. Next time I have it on a lift I'm going to check those engine mounts. I don't know much about them...anyone have any suggestions? Are they rubber? Can they wear out?

    Thanks

    Birdman
     
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  13. JamesH

    JamesH Formula Junior

    May 11, 2001
    268
    San Carlos, Californ
    Full Name:
    James Hom
    I had a rear clunking noise from the left rear of my 84 308 and it turned out to be the lower control arm bushing. It was hard to tell without looking real close. The mechanic showed me there was some brownish dust around the bushing, saying it was metalic dust from the bushings. Clunking noise only happens when going over a pothole in the road
     
  14. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    It was the shock. The damn thing lost all compresion dampning. I replaced it and all is well!


    Thanks to everyone who replied.
     
  15. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
    Full Name:
    Verell Boaen
    Jonathan, somehow I hadn't picked up on your rebuilt shocks not curing the clunk. We definitely can poke around a bit. Hmm, maybe if you put in a day's work helping w/his engine & ask real nicely over a beer JWise will loan you his left side mounts for a test drive while his engine is out.

    The motor mounts don't have any rubber, There is a fairly hefty spring inside the mount housing. Only trouble I ve heard of is a spring rusting thru & failing due to the mount housing holding water.
     
  16. Darolls

    Darolls F1 Veteran
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    Jul 2, 2003
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    Sparky
    I hope you replaced both of them, if not all four!
     

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