2008 Rear Suspenssion Noise

[Mr T]

Folks:

My trusty 2008 Denali XL now has 202,200 miles on it. Motor and transmission going strong. I have a consistent rear main seal leak that I just "deal" with as I don't really want to do all the work to replace it. Well, there is a new potential issue that I don't think I should deal with as it could cause a safety concern.

In 2014, when it had 107k miles, I replaced both rear shocks with Arnott. Also replaced the air compressor because I was getting the Suspension System Maintenance warning. All has been well with that. It still fills the replacement shocks and the ride is level.

HOWEVER, if you drive down a semi-bumpy road, say a residential street with some a mild pothole, etc, rather than just a bump you hear more of a hard "thud". Almost like there is lose cargo. I'm wondering what could be causing that? There are leaf springs not struts on the back. Perhaps a spring is cracked? I need to take a look to see but if so, I would be shocked. I've not hauled a heavy load on the hitch for at least 2 years and this noise is recent.

Any idea what could make such a thud in the rear end? Furthermore, not really sure how to find such a noise when it's not rolling down the road and hitting bumps. I'll get under it and look around but I worry this takes road movement to identify.

Thoughts?

TKH

 

[cmyhre85355]

Check the bolts on the shocks first. That’s probably the path of least resistance initially.


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[Jason in DLH]

You have leaf springs on your ‘08 Denali? I believe you meant to say coil springs.

And what the person above me said. If it’s not the bolts then probably just need new shocks.

 

[02Lightning]

Sounds like a bad damper to me, maybe not the airbag part but the damper. Arnott takes used dampers and runs them on a dyno, it's a pass or fail thing, they don't rebuild the damper part. Or at least that was the case when I replaced mine, I went with new BWI.

 

[Bill 1960]

Lots of possibilities, shock mounting bolts, sway bar end link bushings, sway bar frame bushings, control arm bushings. And the panhard bar. I’d start with a visual inspection.

Sometimes it’s possible to duplicate a suspension clunk by having an assistant push the body side to side or jumping on the bumper. If you temporarily remove the shocks it’s easier to get the suspension to move while you’re diagnosing.

 

[wjburken]

There are 100K on the rear shocks and 6 years. Very plausible that you have gotten a full life out of them and may need to replace them.

Might also check your rear sway bar links, pan hard bar connections, link bar bushings, etc.

 

[Mr T]

All excellent feedback. I will be under it this weekend doing that full inspection. May likely be multiple new parts/bushings. Many miles/years things will get worn and soft rubber becomes crusty.

 

[Jason in DLH]

Please let us know what you discover.

 

[jz57]

Don't forget check rear parking brake shoe being loosing.

Folks:

.....

HOWEVER, if you drive down a semi-bumpy road, say a residential street with some a mild pothole, etc, rather than just a bump you hear more of a hard "thud". Almost like there is lose cargo. .......

TKH

 

[Mr T]

All bushings look good. I need to pull the rear wheels to check the parking brake shoe. I bet that is what it is. I've never replaced it nor really inspected it.