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Something in my driver's side front suspension has a brief knock sound emanating from it and almost feels like some joint or fastener has play in it a small amount when the knock sound is heard.

Basically I'm parked forward facing in a carport with a driveway perpendicular to my vehicle. I reverse to the left, turning my steering wheel counterclockwise. I then brake when reversed enough, shift to drive, turn the wheel clockwise and when my vehicle is something like 45 to 30 degrees off from straight down the driveway I get this knock sound just as I'm advancing and turning into the driveway.

It's getting more frequent, so something is loosening up. Going to jack up the car soon and start tugging on parts and rocking the wheel round and checking bushings, tie rods, knuckles and the like.

I'm wondering if the described behavior would suggest to anyone one particular part that's likely to yield such a sound having been loaded and stressed in the directional fashion my reverse and forward driving would setup. I haven't heard the knock in any other driving pattern, but consistently in this left reverse, forward drive transition period. I drove around a parking lot the other day in random circles, to the left an to the right, nothing much for sounds.

We're dealing with a 2005 Volvo S80 2.5T vehicle if that helps.

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  • 2
    Make and model?
    – tlhIngan
    Commented Nov 21, 2016 at 8:01
  • Your question is too broad for anyone to give you any assistance. It literally could be anything! All we can do is wildly guess, especially since you have not given any vehicle specific details like @tlhIngan asked for.
    – CharlieRB
    Commented Nov 21, 2016 at 17:45
  • Sorry guys, didn't log in till now, 2005 Volvo S80 2.5T. I thought something about the dynamics and ordering would indicate something.
    – jxramos
    Commented Nov 21, 2016 at 20:30
  • CharlieRB is correct, it could be any number of components in your front suspension/steering. To find out for sure you need to get under there or have it checked at a garage.
    – kmarsh
    Commented Nov 22, 2016 at 0:49

1 Answer 1

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Turns out I had a bad rear bushing in the lower control arm on the driver's side.

lower control arm rear bushing failed

It turns out my observation about the reverse and accelerate forward ordering captured part of the story.

This control arms video I found on youtube has a fella explaining some of the symptoms that accomodate failed control arm bushings. I know I did experience one of the symptoms he indicates, about the setting and pulling one way during breaking. I haven't paid attention if the pulling is only to one side or if it alternates as he suggests, but I know for sure breaking pulls to one side, just not sure which side and if its only that side.

ipd Volvo - ipd HD Control Arms - P2 S60, V70 2001-2007

If you've been driving one of these cars you may have seen these symptoms already. One of the things you'll notice is that the car will tend to bump steer under heavy braking, it will take a set and will want to pull one way sometimes and then pull another way the next time that you brake hard. It has all kinds of strange symptoms including not wanting to track straight down the road. The failures show up usually first as cracks in the rubber here in this longitudinal bushing which you can see and flex them back and forth as the bushings wear. And then later after this bushing has almost completely failed the rear bushing which takes force back this direction will start to crack around the center sleeve here. If you've got this level of failure in your car you have a significant deterioration in the handling and the performance of the car and a new set of control arms will make a big difference.

Another reference item that highlighted some symptoms I was experiencing that I think nailed what I was experiencing in the reverse and accelerating reproducibility.

It may require a sudden brake and steer in an empty parking lot to reveal a failed control arm bushing.1

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