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06 Impala Clunking noise rear suspension

3379 Views 1 Reply 2 Participants Last post by  plano-doug
06, 3.9, 123k miles tires 60% good, Brakes over 50% left as well.

I've had a clunk for years and it's not water related as I've seen a post about that.

It's suspension related I believe. Replaced front & rear struts with a Monroe quick strut kit, replaced stabilizer links, the lower easier to replace cross beam bars, the forward to front of axle lateral bars. Only thing I haven't replaced is the sway bar. Replaced the bushings at the same time I did all the other stuff with Moog bushings for the sway and stabilizer links and link kits

It is mainly worse when people are in the rear seats , 1 or more people and the lore the worse the sound. It has been this way all along and even after suspension rebuild.

Wheel bearings, brakes and rotors have also been replaced. All this was done as a 10 year (Dec 2016) complete suspension rebuild which was roughly $1200 in parts including the front rack & pinion, front quick struts, front sway bar and sway bar links. This didn't include an alignment afterwards which was around $70 or so give or take.

The only things that haven't been replaced are the rear sway bar and the support beams from the upper center of the suspension to the outer part connecting to the hub assemblies.

This has stumped me as I worked on suspensions on semi trucks for years and yes they're not the same but mechanical logic applies here plus I've been working on straight Automobiles for the last 6-7 years privately. Self taught plus online diagnostics training including oscilloscope and thee tools.

I think it's probably time to hookup a NVH sensor for my 4 channel Picoscope as this has me at my wits end. I've went up and down both sides of the rear suspension. I didn't do the parts cannon chasing this but rather I replaced all those parts as the car was 10 yrs old when done and bushings, etc were worn along with the rack and pinion leaking oil.

Rides like a new car other than the clunking noise when 3 or more people in vehicle with 1 of them being in rear seat. 2 in the rear seat makes it even worse and with 3 in the rear seat even a small bump is a big thing then.

Let the replies begin and I thank you all in advance.

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The one thought I have is to take everything out of the trunk and back half of the car, then drive it and see if the noise is still there. Maybe get someone to ride in the back while test driving it.

The noise may be suspension, but you want to rule out everything else first. So remove everything that's not bolted down in the back half of the car.

After that, get in the trunk and grab hold of anything that might can move and wiggle it firmly. For example, make sure any speakers in the rear deck are not loose.

There are four bolts in the trunk area that hold the rear suspension mount. Make sure these are all tight.

Stand up in the trunk and get the car bouncing. See if you can hear the clunk.

Next, get it up on a rack somewhere - it helps to know someone in a shop who can accommodate this - and get under it with a big pair of channel locks. Again, grab hold of anything that can move and wiggle it looking for the noise maker.



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