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  • Rear Struts Worn?

    I've got Koni yellow adjustables on my car, front and rear. I have had a creaking sound coming from the rear and took the car into a shop I feel pretty good about. At least I don't think they would try to swindle me. The strut mounts are worn, which is about what I expected, but now they're coming back and saying my struts are worn and need replaced. I seriously have maybe 15k miles on these Koni's, tops. I just don't understand how that could be possible, and aside from creaking I haven't noticed any irregularities in how the car rides at all.

    What would you do?
    99 Black SVT -3L Hybrid, Spec flywheel, MSDS, CAI, 17" Konig Tantrums, Optimized TB & Y, Baer BBK, Bassani cat-back w/ magnaflow res, Koni's w/ H&R

    '06 Volvo V50 T5 AWD MTX- Stock

  • #2
    Ask the shop to define "worn".
    If the upper strut mounts are shot, they're inexpensive, just replace them.
    I've had plenty of Koni struts on many different cars over the years, and <15,000 miles would be a disastrously short lifetime, unless the install was pooched somehow.
    So, looking at your sig, I see H&R springs. Did the install include proper bump stops on the strut piston rods and boots over the strut rods? Koni does have a warranty, but if they see damage to the piston foot valve from not running proper bump stops, they'll void the warranty.
    Are the struts leaking oil at the piston rod seal?
    Are the piston rods bright and shiny and free of pitting and corrosion?

    Struts can fail in several ways:
    1. They can lose their ability to dampen the spring, and results in a bouncy rebound. This is easy to test by pushing down hard on the rear bumper and watching how the car rebounds. If it rebounds cleanly without overshoot, they're probably fine, but if it rebounds and oscillates, they've lost their damping ability.
    2. They can lose their gas charge, and Koni's will do this, sometimes in only a few tens of thousands of miles, but this generally won't affect their performance or damping, and the only way to test this is by removing the strut assembly from the car, removing the spring and testing if the piston rod rebounds after being compressed into the strut cartridge. No slow rebound means no gas, but it's not something you would notice driving the car around on the public roads.
    3. Really old struts can suffer upper bushing wear where the piston rod enters the strut cartridge, this can cause noises and inability to hold a suspension alignment. Again, the only way to test this is by removing the strut assembly from the car, removing the spring and checking for excessive (axial) piston rod play.

    You can do number 1, ask the shop if they removed and disassembled the strut/spring assembly and checked for gas rebound, piston rod axial play, and clean, corrosion-free piston rods.

    Creaking could simply be a dry strut piston rod, this can be alleviated by disassembling the strut and wiping some oil on the piston rods.

    The rear suspensions on these cars are prone to clunks and bumps when the bushings for the anti-roll bar end links rot out where the links pass through the rear control arms. In most cases, you can't see how bad the end link bushings are until you take them apart.

    Additionally, in locales where this is a lot of winter road salt used, the anti-roll bar mounts on the rear subframe can rust away or fracture, leaving the ARB poorly supported, which makes noises and clunks.
    I collect Ford's Red-headed step children.
    1985 SVO Mustang (turbocharged track rat)
    1989 Taurus SHO (supercharged track rat)
    1999 SVT Contour (Sedanus-Grocerygetter-Rapidus)
    2008 Mercury Milan Premier (Comfy boat)

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    • #3
      Thanks for the helpful reply. The shop manager says he can push the strut down by hand and they have no rebound in them. I'm just shocked. I haven't noticed anything odd driving the car. You said it's unlikely I would notice something like this on public roads. Why is that? If there was no rebound left wouldn't the car be bouncing around like crazy?

      Edit: You said Koni's sometimes lose their gas charge but that it won't affect their performance or damping. So it's not only safe to drive but also fine as far as performance?
      99 Black SVT -3L Hybrid, Spec flywheel, MSDS, CAI, 17" Konig Tantrums, Optimized TB & Y, Baer BBK, Bassani cat-back w/ magnaflow res, Koni's w/ H&R

      '06 Volvo V50 T5 AWD MTX- Stock

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      • #4
        After talking with the shop manager again he feels pretty confident that they're ok. He noted no oil seepage and says there is some change in compression and rebound when they're adjusted. I also see other forums where people report the same thing, and that Koni has told them that it's totally normal as long as the strut rebounds when pulled like a spring would do naturally. Of course Koni is closed for the holidays so I can't call them, but I'm feeling better about this now. Thank goodness.
        99 Black SVT -3L Hybrid, Spec flywheel, MSDS, CAI, 17" Konig Tantrums, Optimized TB & Y, Baer BBK, Bassani cat-back w/ magnaflow res, Koni's w/ H&R

        '06 Volvo V50 T5 AWD MTX- Stock

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        • #5
          Originally posted by CLASSVT View Post
          Thanks for the helpful reply. The shop manager says he can push the strut down by hand and they have no rebound in them. I'm just shocked. I haven't noticed anything odd driving the car. You said it's unlikely I would notice something like this on public roads. Why is that? If there was no rebound left wouldn't the car be bouncing around like crazy?

          Edit: You said Koni's sometimes lose their gas charge but that it won't affect their performance or damping. So it's not only safe to drive but also fine as far as performance?
          That's just gas rebound, and if the gas charge has left the strut, as often happens, then the piston rod won't slowly come back out of the strut after it's fully compressed in bump, the suspension spring has to be absent to see this. The strut will still act normally to damp motion in bump and rebound, but now the suspension spring provides all the "rebound" as there isn't any gas charge to help that anymore.Very few gas charged dampers keep their gas charge for their lifetime, and many lose it pretty early, and almost no one ever notices.
          I collect Ford's Red-headed step children.
          1985 SVO Mustang (turbocharged track rat)
          1989 Taurus SHO (supercharged track rat)
          1999 SVT Contour (Sedanus-Grocerygetter-Rapidus)
          2008 Mercury Milan Premier (Comfy boat)

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          • #6
            Creaking is more likely something connected to your sway bar. Either the bushings or the endlinks.
            You would want to check the other suspension bushings too, but the sway bar is the most common culprit by a long shot
            Your car is uglier than I am! uh...that didnt come out right.

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            • #7
              Yes, thank you. They are replacing the end links too, but they said the creaking was definitely coming from the strut mounts. Of course "definitely" is always with a grain of salt.

              99 Black SVT -3L Hybrid, Spec flywheel, MSDS, CAI, 17" Konig Tantrums, Optimized TB & Y, Baer BBK, Bassani cat-back w/ magnaflow res, Koni's w/ H&R

              '06 Volvo V50 T5 AWD MTX- Stock

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