08 Denali with 160k suspension question

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Ponchonutty

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I replaced all spring/struts/auto ride stuff about 12k miles ago. Vehicle rides fine but sometimes if I take off a little hard, I can feel a clunk which feels like either something in the rear or even like a loose driveshaft. Also there's this odd bump close to my house and when I drive over it it seems as if the rear hops over a little to one side. There isn't any other noises and I had a recent alignment just to double check things since I mounted new tires. Could I have control arm bushing issues or anyone else have an idea what to look for?
 

MSGKUNERT

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I have the same problem with mine and from what I can find on here, it appears the u-joints needs to be replaced. Will be climbing underneath tonight and check it out.
 

iamdub

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No. But the clunking when accelerating sharply is a symptom of the commonly broken motor mount(s). The jolt can travel through the frame and feel like it's coming from under or behind you. With the truck in D, hold the brake firmly with your left foot and jab the throttle with your right foot and see if you feel the clunk. You don't have to floor it. Actually, you may want to tap the pedal a few times, a little more each time, until you feel it.

The rear end doing the side-step may be from the design of the suspension with it's panhard bar setup. You may be hitting that "odd bump" at just the right (albeit slight) angle that causes one side to raise and drop at the same rate that the suspension can absorb and rebound from it, causing an oscillation between body roll and the axle. The fresh shocks quickly regain control, but there's still a lot of body weight that was just tossed around by that bump. Also, there's a good chance the bushings in the links are worn, increasing the lateral slop and momentary loss of articulation control.

Your motor mount(s) may be fine and the clunk you feel actually is from the rear end. If this is the case, you have some seriously worn suspension components (primarily bushings) or something's broken (rusted out?)
 
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Ponchonutty

Ponchonutty

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I will try to see if I can get the motor to make the noise. Personally I'm thinking of worn out rear bushings. Sort of reminds me of my Wrangler when the rear lower trailing arm bushings went to hell. There isn't any major rusting issues that I've seen. I always keep things clean and recoat stuff
 

iamdub

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I mentioned mounts first because I had the same feeling and noise in mine and broken mounts are very common. By the way it felt and sounded, I swore it was something in the rear suspension but traced the clunk to a broken driver's side mount. Of course, all we can go off of is a typed-out description of what you're experiencing and your problem may very well be elsewhere. Good luck and post what you find.
 
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Ponchonutty

Ponchonutty

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Iamdub, you were right. Drivers side mount was trashed!
IMG_2759.JPG
 

iamdub

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Did you throw it away?

I need a broken mount for experimental purposes.

Oh- did that stop the clunk you felt/heard?
 

Big Mama

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First question is did it do this prior to the suspension work? If not, I'd double check your work. One common mistake is to do all of the bolt tightening with the truck on jacks or a lift when they need to be done with the truck under full weight. If that's all ok there's a TSB about this clucking noise. Some fix it as easy as removing and greasing the u joints or splines. Some have replaced the U joints all together. Check the forums for this noise and check the TSB.
 
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Ponchonutty

Ponchonutty

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First question is did it do this prior to the suspension work? If not, I'd double check your work. One common mistake is to do all of the bolt tightening with the truck on jacks or a lift when they need to be done with the truck under full weight. If that's all ok there's a TSB about this clucking noise. Some fix it as easy as removing and greasing the u joints or splines. Some have replaced the U joints all together. Check the forums for this noise and check the TSB.
No it didn't make this noise before OR after suspension work
 

RED TAHOE LS

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Good diagnosis on the motor mount, although the CLUNCK in the rear end is rear end torque. Vehicles used to have a PINION SNUBBER, which was a mount directlt over the pinion with a rubber mount that would cushion the torque in the rear end reducing the travel. In other words, that's the noise your hearing, my Tahoe also does it and has since new, @ 197,000 there is no affect in performance, JMHO.
David g.
 
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Ponchonutty

Ponchonutty

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Well my rear end clunk noise is completely completely gone. Would have never thought a motor mount would have noise travel to the rear like that
 

dirtydenali07

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I have an 07 Denali XL. It was on the lift the other day for inspection, so I checked everything I could for the dreaded thump on takeoff. Only thing I found was left front diff mount is shot. I can grab the yoke and move diff up and down about 3/4".
 

95escahoe

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Have a similar issue on mine like this I'll check these out


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iamdub

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I just thought of something: Maybe the broken motor mount(s) allowed everything to twist more than it should, causing the trans mount to break and that's why there's a clunk that sounds more rearward cuz it's pretty much under you but to the middle. I'll have to inspect my trans mount...
 

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