Knocking sound when going into small potholes

[Lug1]

Hi All,
I'm clueless about this one, and know it's a very broad question, but, barring taking in to the shop for diagnostics, (and I asked too many favors of them lately), this is my only resort.

So, in the past few weeks, any time I drive into a potholes or any other slight "challenge" on the road, I hear a knock sound, from underneath. It's very likely coming from the front axle area, sounds like it's coming from the left side - buy, hey - I'm sitting on the left side when driving so duh...

I tried recording the sound but well, the wind gets in the way

There is a direct ratio between the size of the pothole and the loudness of the knock. Larger pothole=knock is louder. Although, with some potholes- no sound at all, so it's not there 100% of the time.

I know it's very vague and broad issue, in any case, any ideas, pointers as to the usual suspects are welcome.

 

[SilverRidgeRunner1]

Hi All,
I'm clueless about this one, and know it's a very broad question, but, barring taking in to the shop for diagnostics, (and I asked too many favors of them lately), this is my only resort.

So, in the past few weeks, any time I drive into a potholes or any other slight "challenge" on the road, I hear a knock sound, from underneath. It's very likely coming from the front axle area, sounds like it's coming from the left side - buy, hey - I'm sitting on the left side when driving so duh...

I tried recording the sound but well, the wind gets in the way

There is a direct ratio between the size of the pothole and the loudness of the knock. Larger pothole=knock is louder. Although, with some potholes- no sound at all, so it's not there 100% of the time.

I know it's very vague and broad issue, in any case, any ideas, pointers as to the usual suspects are welcome.

Had a sway bar bushing do the same exact thing

 

[thatoneguygeoff]

Bad ball joint?

 

[Charlene]

Bad sway bar bushing! Had this exact same issue and it ended up just being the sway bar banging on the metal bracket because of the bad bushing.

 

[gamefreakgc]

Get under your truck with a rubber mallet and start hitting stuff. You'll find the loose part soon enough.

 

[02SE]

It could be any number of things. I'd get under your 4Runner, and try to find anything loose.

Barring that, I'd suggest having someone that specializes in NVH issues, take a look at it.

 

[Lug1]

Alright, thank you everyone, I guess the sway bar bushings need to be checked. I'll get under the truck tomorrow and have a look around. Did some youtube search for more details.

 

[I_bRAD]

check your ball joints and tie rods while you're under there

 

[JRZEE2000TR4LTD]

Also check the swaybar endlinks. I found mine loose in the LCA mount. Might also be broke up top where the bushings are. Try to rock the truck back and forth from underneath. I kinda bench pressed mine.

 

[Lug1]

Looked under:
Sway bar bushings are broken, that's for sure, so that's one for the to-do list.

Will need to check ball joints, too.

Yippee! (/sarc).

 

[gamefreakgc]

If the bushings are completely toast and has metal to metal contact you found your noise!

You'll be surprised on how well it will handle once you replace the bushings!

 

[Lug1]

The sway bar bushings are not total bust, there's still plastic there. They are however broken in half, with the pressure of the brackets holding them in. Obviously, they'll need to be replaced. With how "fast" I take care of things here.. I hope I can get this done before the winter gets in full gear.

 

[jeremyc74]

I replaced my sway bar end links with some from Rock Auto (Beck Arnely I think) and they were crap again in less than a year. This is probably one of those things you're better off paying for OEM, or at least one of the more trusted brands.

This isn't a great picture, but you can see how the bushings are already cracked, and I'm getting a popping noise when I back out of parking spots and go back into drive.

 

[Lug1]

So:
Replaced: Sway bar bushings (were done with, worn out), there was one broken sway bar end link - replaced, and the other side end link, as well.

But, - the knock is still there.. hmm..

A friend that knows his mechanics tested the lower ball joints, and as far as he can tell - they are in good condition.

Any other ideas folks ?

Thank you.

 

[BlackCat914]

So the swaybars are new, no play in ball joints or tie rods? My next guess would be strut mounts or rack bushings.

 

[afg10000]

Control Arm bushings could be a likely culprit. If ya gotta change all that stuff, do yourself a favor and replace them all with polys.