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Discussion Starter #1
Hey. I got a 2004 Envoy. It's my son's. He said he was driving home and suddenly felt a big "thunk" type sound coming from the back.

I drove it around the block and sure enough, don't really quite know how to describe it other than a thunk sound coming from the rear. Noticed it mostly while turning to the right but it drove straight and engine seemed fine. Something perhaps in the drivetrain? It sounds internal to me. Looked underneath and saw nothing obvious hanging or broken or anything.

Any ideas where to start looking?
 

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Discussion Starter #3
Thank you. Will check tonight when I get home. With a bad u v joint with the car still drive just fine for a little bit? I'm not going to drive it I was just worried about him driving at home last night.
 

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2004 GMC Envoy SLT 4.2
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If a U joint is bad enough to clunk , it likely isn't far from letting go , totally .
There's a fairly high amount of pressure passing through that joint .
 

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2002 chevy trailblazer_ltz
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Drive shaft u joints.
Drive up a hill that you can put a load on it. Some torque. Then down the hill giving light gas but not all the way off.

Lastly if it's really bad when starting from a stop go hard on the accelerator. If you've a really bad u joint it will clunk then.

If no noises in the above scenario it's not bad enough to worry about yet.

There are also rear sway bar and drop kinks back there. If bad they'll clunk

Good luck
 

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Discussion Starter #6
I climbed under there last night just to visually look at the U joint. It seemed pretty solid. I'll check the sway bar see if he has any play to it. I'll give it a chance to check out that U-joint this weekend. I appreciate the response
 

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2007 chevy trailblazer_ls
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Hey. I got a 2004 Envoy. It's my son's. He said he was driving home and suddenly felt a big "thunk" type sound coming from the back.

I drove it around the block and sure enough, don't really quite know how to describe it other than a thunk sound coming from the rear. Noticed it mostly while turning to the right but it drove straight and engine seemed fine. Something perhaps in the drivetrain? It sounds internal to me. Looked underneath and saw nothing obvious hanging or broken or anything.

Any ideas where to start looking?
Look at your trailing arms. I ended up with 2 broken welds at both upper trailing arms one morning. I was able to limp home the weld them up since I have a welder. Arms are generally not available over the counter. DO NOT DRIVE THE VEHICLE! The arms are not that difficult to R/R, but you have to get them first.
 

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2004 buick rainier
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My son's Cadillac CTS '07 rear-wheel drive had a similar sound. There was a bushing on the rear differential that had basically disintegrated in place. Easy and not too expensive replacement/repair. We could repeat the clunking sound by, as we are driving, coast for a little while by taking the foot off the gas, then resume pressing the gas pedal: clunk. Perhaps similar issue for you.
 

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Discussion Starter #9
Thanks. Kinda isolated the sound from behind the drivers side wheel. Have yet to pull it off and look it all over. Appreciate the feedback.
 

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Thanks. Kinda isolated the sound from behind the drivers side wheel. Have yet to pull it off and look it all over. Appreciate the feedback.
I've had to replace the rear sway linkage twice, both times from the drivers rear. Stopped my clunking in turns and bumpy roads. I've found that no matter how tight I get the nut, it wants to work it's way loose and it ends up borking the linkage.
 

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Discussion Starter #11
Got this picture tonight of the rear sway bar? It's not broken but there is like no bushing on any of them. Looks all dry rotted. Guessing as the wheels turn the bolt is slamming around in the hole creating the sound. I took a video of the sound but can't upload because it says the file extension is not correct.this sway arm has seriously 1/2" play all around.

Please tell me this could be it. What file format for videos can I upload?
20191121_153858_HDR.jpg
 

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2006 chevy trailblazer_lt
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Uh, yup, that picture is the sway bar link from the Trailblazer, Bravada and Envoy line of SUV. Change out the driver's side and passenger's side sway bay links at the same time. The worn stock sway bar linkage is a common issue with this suspension. From this picture, I notice that the sway bar looks newer than the sway bar links. I wonder, was the sway bar itself changed out and not the sway bar links at the same time? 🤔

I said the hell with it and ordered a whole new front and rear suspension kit from Amazon for my '06 Trailblazer. I wanted it done correctly all at once and not be a hodgepodge of old and new parts. My mechanic thankfully installed everything for me, after I asked him about the suspension package before ordering; but of course on the bill "customer parts, no warranty."
 
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