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Discussion Starter · #1 ·
This has been going on for a while, and has recently gotten a bit worse and is now making the clunking noise much more often in less demanding situations, accompanied with a periodic metallic sounding rattle.

Anyway, 3 months after getting all new suspension installed without an alignment afterward (Bilstein HD's all around, Hotchkis sway bar + moog links + poly bushings for front sway bar, OEM sway bar links up front, airlift 1000 kit for rear coil springs) started to get a clunking noise when the suspension would articulate over an object. If the truck is driving straight and goes over a speedbump and the suspension on each axle flexes together, no sound is produced. If the same speed bump is approached so that the right or left side of the truck is going to go over it, it produces a clunking noise. This occurs when going 10mph or slower, so not much speed is necessary, and it does it at speed in turns too. When one of the front wheels hits a bump and flexes up, it will clunk. Same thing with the rear axle, and the noise this time comes from more towards the rear.

Sounds like 2 separate issues, and I've been putting emphasis on the sway bars and links, but everything is tight as can be. Less of actually tearing the suspension components apart one by one, I have no idea what else to check? What makes it difficult is the fact the noise radiates from front and rear, whichever axle gets affected, so I find it hard to believe that 2 wheel bearings, or something on each axle each went bad at the same time. I've thought about the possibility of it being the CV axles up front, the driver side one slings grease into the frame housing surrounding it, but I don't think it would cause the noise.

If the truck is parked on level ground, and I stand on one running board and rock the truck back and forth with all my effort, it will clunk once. Then I will go to the other side and do the same thing and it will clunk once again, or "back to nominal position." So its obviously something that is sliding around or moving in its position otherwise it would just keep on making the clunk sound if it were something that had gone bad. My first step is to have the mechanics take the sway bars apart and even off, and then drive it around to see if I can replicate the sound. If the sound is gone, then I'll just get an alignment and the SuspensionMaxx sway bar links. Other than this, I have no idea what route to explore or what to take apart.

Any suggestions on this? Keep in mind the running boards test aforementioned, as that might help in narrowing down what to check out. Thanks guys/gals!
 

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I wonder if something has gone wrong with one of your body mounts. I've heard a similar sound in similar conditions before and it turned out that it was related to the body mounts. In my case it was body mounts that were not installed in the factory.

Tightening up your suspension like you have may be placing new stresses on the frame to body connection.

I would check to make sure that: 1) all the body mounts are in place and in good condition; and, 2) torque the body mounts to their factory spec.
 

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Discussion Starter · #4 ·
Yeah I've thought about engine mounts and body mounts but didn't really explore those yet. You are right about the stresses thing, but with all the gear I have on it now, it [in theory] SHOULD be flexing less because the suspension has the body in more control. But maybe the opposite is true. Maybe the bolts in the body mounts are rounding out their casings and now they are slipping around?
 

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Yeah I've thought about engine mounts and body mounts but didn't really explore those yet. You are right about the stresses thing, but with all the gear I have on it now, it [in theory] SHOULD be flexing less because the suspension has the body in more control. But maybe the opposite is true. Maybe the bolts in the body mounts are rounding out their casings and now they are slipping around?
Certainly your suspension is flexing less but keep in mind that you're suspension is directly connected to the frame and that the body rests on top of the frame. So less flex in the suspension will introduce more flex in the frame when going over a bump. And more flex in the frame will cause movement where it meets the body. These meeting places are the body mounts. I think it's worth examining considering the length of the frame under your XL compared to its width. Plus those body mounts are pretty easy to get at - but make sure you get them all: uppers and lowers.

I've seen GM leave off lower body mounts on some BOF vehicles and just use uppers with a bolt and washer underneath. Strange noises persist when going up driveway curbs and other such slow but large impacts.
 

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Discussion Starter · #6 ·
Maybe its our lovely SWPA roads? lol
And my style of driving :p

Certainly your suspension is flexing less but keep in mind that you're suspension is directly connected to the frame and that the body rests on top of the frame. So less flex in the suspension will introduce more flex in the frame when going over a bump. And more flex in the frame will cause movement where it meets the body. These meeting places are the body mounts. I think it's worth examining considering the length of the frame under your XL compared to its width. Plus those body mounts are pretty easy to get at - but make sure you get them all: uppers and lowers.

I've seen GM leave off lower body mounts on some BOF vehicles and just use uppers with a bolt and washer underneath. Strange noises persist when going up driveway curbs and other such slow but large impacts.
Good points. Certainly makes sense because the noise seems to radiate from whichever side is hit. Driver front/rear, passenger front/rear all have a sound that radiates from that general location. Torquing them to manufacturers specs though might not solve the problem for the long term if they even need tightened though... I just want to make sure I'm not doing damage to something that won't last in a long time from now.
 

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I know this is a very old post but I’m wondering if the problem turned out to be the body mounts. My 2007 Saab 97x with 286k miles has annoying and as yes undiagnosed pop noise at slow speeds like in a driveway especially when the front or rear wheels hit the garage floor lip. Almost everything has been replaced but that’s a story for another day. Thank you.
 
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