2008 Cobalt knock sound over bumps


Streetwise
05-24-2014, 04:22 PM
There's a front end knock when driving over bumps. It's not incredibly loud and doesn't vibrate throughout, but it's noticeable. I checked the struts and they look pretty good, like new and turning the wheel they look fine. There is no issue with the shock travel; it bounces right back.
I changed the lower control arm bushings on both sides. They did look worn. The sound is still there.
It's independent of each side. If the left tire hit a pothole it knocks on the left - same for the right.
Next I think I look at the sway bar. everything looks very clean and rust free. The other 2 rubber bushings on the control arms looked brand new.
Any ideas?

gmtech1
05-24-2014, 09:24 PM
Check for looseness in the sway bar end links. Pretty common for them to wear and cause noises.

Streetwise
05-24-2014, 10:00 PM
Check for looseness in the sway bar end links. Pretty common for them to wear and cause noises.

Is that hard to do? Easier than the control arm bushings?

gmtech1
05-24-2014, 11:17 PM
Easier than the bushings. Grab ahold of the ends of the sway bar and check for any up and down movement in the link ball sockets. Should not be any play.

Streetwise
06-02-2014, 10:39 PM
Easier than the bushings. Grab ahold of the ends of the sway bar and check for any up and down movement in the link ball sockets. Should not be any play.

The end links/sockets look new and I can't get any play by trying to move them. The sway bar bushings do look a little worn and also look like they're not a snug fit so maybe they're worn. I'm going to replace them just because it's kind of an easy replacement.

I've seen guys grease them, is that a good idea?

sstocker31
01-18-2015, 03:47 PM
I know this is an old thread, but i'd like to add this anyhow for extra information. With the electric power steering there is a plastic bushing internally in the PS unit, and I think this is where the noise comes from. Search youtube for a good video explaining the solution.

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