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Knock knock, needs reapir

My '07 Pontiac G5 GT has a knocking up front. 140K miles on the clock, well maintained, many new parts up front in the last year from worn OE components. I’ve had a reputable local shop, as well as a dealership check things over a total of 3 times. All was found tight & safe to drive. I hear it when driving over a field of patched potholes, driving in a grassy meadow (makeshift parking areas for fairs/carnivals/etc). Sometimes it knocks when torque is put to the front wheels from a standing stop. The car handles solid without wandering, and no abnormal tire wear. Parts that have been replaced: lower control arm bushings, sway bar end links, engine mounts, struts and springs, swaybar bushings, ball joint, both tierod ends, intermediate steering shaft. I welcome all recommendations you may have, including ones that involve herbs, essential oils, or incantations by the full moon.

This sounds like the classic symptoms of a tired sway bar bushing, sway bar link, or strut mount. My suggestion would be to SAFELT AND SECURELY elevate all four corners, slide underneath, and start vigorously shaking parts. You’ll probably find the knocking. My money’s on a simple sway bar bushing.


Sway bar bushings are new, and wouldn’t be affected by engine torque. Yep, already checked this out.

Spoken, or tapped, via Droid.

If the struts have been replaced but the strut mounts have not… I’d suggest the strut mounts are the problem, especially if the sound you hear is much like carrying loose 2x4’s under the hood.

It wouldn’t hurt to eyeball the motor mounts as well.

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It seems like your shop has pretty much replaced most everything that could cause that … hmmmm … well at least they are on top of the problem … the only other things I can come up with are the front cv joints – assuming a front wheel drive vehicle – or the transmission mounts.

I would agree with possibly CV joints, strut mounts, and since you used the words “ball joint” in the singular I’m not sure if this means only one was replaced. If so, that leads to the other.

Some brake designs are more prone to knocking than others. I have not done a brake job on a GM car since the mid 80s but they used to get noisy unless you took two ball peen hammers and peened over the metal ends of the pads to fit tighter.

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I just had a thought to add.
When struts are replaced, the rubbery bits involved aren’t usually changed. The process involves removing the strut assembly, compressing the spring, removing the holding nut, removing the spring and rubber spring mounts/bushings, and moving everything over to the new damper. The spring mounts/bushings get old and hard over the years and can begin to fail. Another common problem that causes noises is improper orientation of the spring mount, the rubber bushing, and the spring itself.

Is it possible to find out if the rubbery bits were changed when the struts were done? If they were, they should be on the parts list on your copy of the shop order.

NOTE: this is just an additional idea, not to be confused with an actual diagnosis. :grin:

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The other ball joint is still solid. It’s not OE. I rebuilt the struts from all new parts before my mechanic put them in. He double-checked everything I didn’t have to change anything. I replaced the brakes myself, and they don’t need the ball peening, and all was torqed down. All engine and transmission mounts that had rubber where replaced in part of this campaign. I’m hoping I don’t have to sell the car over this in the future. I really would like to nip this thing when it’s small to avoid something expensive later, but it doesn’t seem the case.

I agree

The S10 was sold through 2003, and it used that design, for example

There is a bearing in the upper part of the strut. Did you replace that. Reference Item 3.

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