Over the past year my LS has developed a knocking sound on the front passenger side when going over a bump. Does not appear to be related to the sway bar bushings as the sound is the same whether the bump is across both front wheels or just one.

Could a shock make this noise? I've checked everything else in the suspension, and all seems well. Today I removed the nuisance shock and although it has leaked quite a bit of oil, it seems to not be busted. It resists when I compress and expands on its own, albeit to a lesser degree vs a new shock.

Before I go and order new shocks from sewell - does anyone have experience with this?

Last year I replaced my LCA bushing hoping this was the cause - to no avail. Tire shows no sign of uneven wear, which points to a shock absorber problem to me, but don't want to spend the money when this is not the culprit!

 

It could be the strut mount. I had this issue on my Avalon.

 

Didn't occur to me that it could be the mounts. I noticed a very minimal amount of rubber shavings in the mount when I removed it. ..must be it.

Thanks!

 

There is another castor arm bushing in there too. Have that one checked. Strut mounts are not common.

 

ive had the exact same issue since I bought my LS last October, a few others have as well.

Hit a bump and I get a very loud BANG, it hasn't gotten any better or any worse, over the 8 months of driving it.

Also when im making a strong left turn I can almost feel a 'pop' from the right side, and it seems like something is loose.

 

Seems like this would be an easy problem for a good alignment shop to find.

 

Does the pop sound like it's metal making the sound? Could be your brake pads shifting and hitting against the rotor, a failure of the fit kit (metal clips that hold the pads in place). Cheap fix if it is, normally a $10 part from the dealer.

 

Always start with the most common and work your way from there. LCA and castor arms are by the far the most common.

 

thanks , but no its not the pads im sure, too loud to be them.

 

I already swapped out my rear LCA bushing. Where is the caster arm bushing? It is the top wishbone bushing?

 

You know, castor arm may not be the right term. It's what was used by the tech on my car but it does not seem to be called that by Lexus. I'm thinking its the lower control arm but there are two bushing. One is attached to the arm (4620/4640) and cannot be replaced without replacing the whole arm. There other, number 2 (48655), can be.

If both of those check out, next to look at is the lower ball joint and upper control arm assembly.

 

Just finished my front brakes on my LS430 and hoped that would cure the very same issue. It did not. While I was down there I noticed my lower control arm bushings look pretty bad. I will start there and move along from that area. I need to find some Energys or something poly to replace them with. I did poly on my Del Sol and the controllability is awesome with a nice comfy ride.

 

Poly is bad news on the ls430. It will ruin the ride. It's not a sports car. OEM or Roca are the only good choices. The main lca bushing is oil filled.

 

I checked and it appears neither the upper or lower control arms have an issue. Ball joints and tie rods are fine.

Only other thing I can image is the strut mount or sway bar bushing, but both look fine, so I'm kind of stuck here. Any other ideas? It could still be either of these - as rubber flexes under load and may clunk, but not certain.

 

Yes, go back have everything re-torqued. If they were not torqued down right in the first place they will loosen over time.