2002 Chevy Silverado clunking noise on acceleration

VITAMIN-E

MEMBER
2002 CHEVROLET SILVERADO
V8
4WD
AUTOMATIC
15,900 MILES

When accelerating, there is a "clunk" coming from the front end (I think on the Driver's side). This has been going on for awhile and I had assumed it was one of the front half-shafts but now I'm not so sure. When the "clunking" initially started, the tires showed no cupping so this re-inforced to me that it was the axles as I assumed the suspension was tight. Now, however, the driver's side front tire has started to cup.

Upon inspecting the other day, both CV boots on both axles are intact. The axles do not feel like they have tight spots in them when I turn the wheels left and right and rotate the wheels.

I put a pry bar on both (driver's side) ball joints and all 4 of the control arm bushings. There is movement in the upper control arm's front bushing. It moves about 1/8" to 3/16" when pryed on.

Q1: What is the (visual) standard for movement in a control arm bushing. Zero, right?

Q2: is one bad control arm bushing enought to cause the clunking?

Thanks, Elliott

3 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Hi Elliott,

Thank you for the donation.

Bushings are made of rubber so there should be some form of side movement when force is exerted, it cannot be zero.

Any bad bushing can cause clunking as during acceleration, torsional force will push the arm into contact with anything nearby.

What is the clunking noise like?
Is it repetitive/continous duriing acceleration or only once every time you accelerate?
Bushing noise would happen in singular pattern, drive train would be continous.

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Saturday, September 27th, 2008 AT 10:14 PM

VITAMIN-E

MEMBER
2 POSTS

KH, thanks for the info and congratulations on a great and useful site!

While putting new shocks on it today, I tugged around on the passenger side upper control arm bushings as well. Again, rear one seemingly doesn't show any movement to the naked eye, while the front one will move the same amount as the one on the driver's side. So, based on that quasi-logic, I guess they're both good. I had thought from previous experience (a high school job at Roy's Texaco garage a LONG time ago) that there should be zero movement in them. Must be confusing them with the ball joints. Speaking of which, I can't really get a pry bar in between the UCA/LCA and the knuckle to try to find movement in them. Is there another way to see if they are bad short of taking the knuckle off and seeing if they turn or are loose?

Clunking is only on accel or decel. Used to be one "clunk", now maybe I get a quick double "clunk". While having the wheel off today, I pulled around on the passenger-side half shaft and felt what I thought was radial looseness in it. It will telescope axially about 1/8"+. Normal, no?

Funny thing is, CV Joint doesn't bind or feel tight when rotating the hub while the wheel is turned fully left or right. Again, past experience (I thought!) Told me that I would feel a "bind" in it if CV joint was bad.

Thanks,
Elliott

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Sunday, September 28th, 2008 AT 10:47 PM

KHLOW2008

MECHANIC
41,815 POSTS

Hi Elliot,

Yes, ball joint would have zero movement but not bushes. You can use a large screw driver to pry but visual inspection for frayed rubber at bushes would be a good way of checking if it is bad.

Try to unload the pressure on the balljoints by jacking the lower control arm. You can then test the ball joint for free play.

Half shaft should not have much axial movement but was the amount of movement inclusive of the differential gears free play.

CV joint would not bind when faulty unless it is in very bad condition whereby you would notice it while turning.

Being a 4WD, you need to check the propeller shafts U joints regarding the clunking noise.

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Monday, September 29th, 2008 AT 10:37 AM