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Author Topic: Identifying bad front suspension  (Read 113 times)

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On3go

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Identifying bad front suspension
« on: January 13, 2020, 08:35:07 AM »

Hello all, I am trying to figure out what may be going on with my front end. When I drive over bumps, road defects and such, theres clunking in the front end. When going over speed bumps, unless going crawl speed, sounds like the suspension slams back down. I looked at the part numbers on the struts thats on the truck and its odd pn #20842281 which online search comes up with ac delco 580-433 Now when I run the rpo code (7F2) the part number comes up 580-434 of what's supposed to be on the truck. Could this possibly be why the suspension is acting funny? It's hard to believe my 02 tahoe takes bumps alot smoother with no sound over a 13 Avy LTZ. Any help is greatly appreciated
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BainMan

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Re: Identifying bad front suspension
« Reply #1 on: January 13, 2020, 09:46:28 AM »

In my opinion, inspect/test the ball joints, tie rods, sway bar end links and sway bar bushings first before going after the shock (unless it's leaking) if you're hearing a clunk.

580-433 and 580-434 are both for the electronic suspension like you have in the 13 LTZ, I'm not sure on the difference just yet between the two except the RPO codes...

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2010 LTZ, bone stock 5.3

On3go

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Re: Identifying bad front suspension
« Reply #2 on: January 13, 2020, 09:58:08 AM »

The sway bar bushings and endlinks were just replaced. They were completely broken off. But the truck still did it before the replacement. As far as ball joints, I tested those as well, no play at all. I have not checked the time rods yet, but will shortly. The struts have that sleeve that protects the rod from dirt and debris, I've tried messing with it to see beyond it but it's a pain in the ass to push up especially with the limited room to work with.
Also I purchased the struts based off the RPO code, the truck was purchased with 73k on it, and the more i dig into the vehicle, the more I'm finding it was ran rough. The dealer i bought it from has an as is policy, and when test driving it, were no rough roads so it didnt raise suspicion. I'm suspecting these are not the original struts, being the rpo search results 434 struts not 433. Only search the 433 came from was looking up the direct number off the struts
« Last Edit: January 13, 2020, 10:01:17 AM by On3go »
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BainMan

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Re: Identifying bad front suspension
« Reply #3 on: January 13, 2020, 12:03:15 PM »

Similar to how you likely checked the ball joints, lift and support the vehicle, then jack one control arm up to de-load it and grab the coil spring with both hands and see if you can make the mount move, if it is loose or makes noise then something is wrong.

Now I'm confused, you also bought new struts? Are they installed?

I see what you're saying about the part numbers, you're correct the 7F2 goes with the 580-434 part. I can't (yet) find specs that describe the shock size & travel.. Both parts appear to work for the 2013 Z55 autoride suspension but are tagged for different sub-suspension RPO codes...

Anyone know a way to lookup the tech specs of https://www.rockauto.com/en/moreinfo.php?pk=3977454&cc=3034466  vs https://www.rockauto.com/en/moreinfo.php?pk=4207935&cc=3034466   ? Wondering if they are functionally different...
« Last Edit: January 13, 2020, 12:47:26 PM by BainMan »
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2010 LTZ, bone stock 5.3

On3go

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Re: Identifying bad front suspension
« Reply #4 on: January 13, 2020, 13:22:35 PM »

Ya I purchased the correct struts already. I havent installed them yet, but purchased for precautionary purposes due to mileage/possibility of being the wrong ones already on the truck.
By what you're saying, you think it could be a possibility the mount could be bad? I usually can tell when a strut is bad, but with these being electronically dampered, I havent a clue. First time dealing with this type of strut
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BainMan

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Re: Identifying bad front suspension
« Reply #5 on: January 13, 2020, 14:48:39 PM »

About the mount, I'm just trying to help rule things out, if the strut mount can move side to side something is wrong. I doubt this is your issue but it should be ruled out if you've got the truck in the air anyway.
For the purposes of diagnosing a clunking noise, forget the struts are electronically dampened, they're just struts.

Did you deload the lower control arm (jack up on it) to test the ball joints? Were OEM parts used on the sway bar links?

Is everything tightened to spec again? It seems you've pretty much ruled everything out, which means we overlooked something or the noise isn't coming from the suspension. If you're confident it's not in the front suspension ( i think you said individually each part was good) you could look for loose body or motor mounts.

Another line of thought, can you replicate the noise while stationary and rocking the truck? Then you can lay under the truck while someone else rocks it, easy way to diagnose if you can replicate the noise that is...
« Last Edit: January 13, 2020, 14:57:07 PM by BainMan »
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2010 LTZ, bone stock 5.3

On3go

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Re: Identifying bad front suspension
« Reply #6 on: January 13, 2020, 18:06:09 PM »

Sway bar links are Moog, but the noise was there prior to installation. The truck literally had no front links, they snapped somehow. But ya, everything's torqued to spec, everything seems pretty sound, only thing I can think of is the top mounts on the struts. TBH I think the suspensions kinda whipped anyways. I'm gonna try the tie rods next when I have some spare time.
I very much appreciate your time and effort in helping diagnose this issue, you've given some good info to help.
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frito

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Re: Identifying bad front suspension
« Reply #7 on: January 13, 2020, 19:30:33 PM »

Have you che med pitman arm, idler arm or CV joints?
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Bumblebee - '03 Z71, FTDRL, All On High, Sail Panel LEDs, Bumper Cup Holders.  Decisions, Decisions...
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