Threxx

I have a 99 GS400 w/ 75k miles. It has had a popping noise coming from what sounds like the right rear suspension for almost a year now. An independent mechanic, firestone, and the Lexus dealer have ALL basically said they couldn't find anything loose or broken and then said maybe it's my chassis braces, but they (and I) checked and they are on VERY tight, so unless one of them is sliding around under pressure, I don't think that's it.

Here's the best I can describe it:

- When I'm taking a medium to hard RIGHT turn it's almost gaurenteed to make the noise. Then pretty much the next time I might a LEFT turn or sometimes even if I just hit a bump and cause the car to settle a little bit, it'll "pop" back into place. So in other words if everything is 'settled' and I made a LEFT hand turn I won't hear anything, because it's already settled. I have to first make a right hand turn to "unsettle" it.

-If I go over a rough parking lot full of dips and bumps, uneven speed bumps, etc... basically anything that causes a sharp left to right swaying motion I'll hear the popping noise sometimes several times quickly.

- It sounds almost like something that first pops out of place and then pops into place. Aa quick, short, but loud popping noise kind of metallic sounding I guess, but not like a hard "clanging" noise like you might expect metal on metal to make. To me it almost sounds like a worn strut except it pretty much only does it when the car is swaying, not when I just hit a bump, plus all the mechanics have said the struts are fine.

Please help... it's embarrasing to drive this car in public almost - it sounds like I'm driving a beater when I'm really driving a 50k dollar car with only 75k miles on it!

bitkahuna

iTrader: (20)

What springs/shocks or coilovers do you have? Regardless, (and I'm no expert!) I'd suspect the spring is not seated in the mount properly or the suspension mount itself is moving somehow. As you said, I doubt it's the bracing, but you could always take that off to make sure it's not.

Can you repeat it at will? Is there a spot you can make it happen pretty consistently? If so, then take a Lexus tech or other mechanic to that spot so they can hear it.

Threxx

I have the factory original stock suspension all around. I did replace the factory sway bars with daizen sways and poly bushings, which is when this issue started happening! But I figured it would go away when I went back to my stock sway bars and original bushings (which is what I have now), but it didn't.

The only mods I have now are the front and rear strut tower braces, front and rear chassis braces, and rear suspension bracing kit (as listed in the sig). Oh and SS brake lines (though I'm sure that wouldn't be it)

Oh, I hear it pretty much any time I make a right turn under 20-30 MPH as well as through bumpy parking lots and the head Lexus technician at the only Lexus dealer within a couple hundred miles of here has heard it loud and clear many times as well but says they just can't figure out what the source of it is.

Heck, I forgot to mention, but it seems to have 'moods'. There are days when it's harder to 'agitate' it and days when it's so bad that it will do it even if I hit the brakes or gas relatively hard or just driving over little bumps. On the days that it's really bad I can usually literally park my car in the garage, get out, grab the car from inside the right rear wheel well, pull up on it, let it down, and repeat the motion to get some momentum going and it'll start popping and clanging just by doing that. Unfortunately the one time I had it doing that and had the chance to get under it, I drove it up on my ramps and it stopped making the noise - I couldn't duplicate it when it was up on ramps.

Adam2562

iTrader: (2)

i think i had this problem on my solara.. try getting new sway bar links?

rcyo1

iTrader: (23)

if this noise started happening after you installed these aftermarket suspension parts, then you answered your own question. now you have to pin point what is causing the noise. sounds like the the the rear lower chassis brace or the Tom's 6-piece rear suspension bracing kit on the right rear is probably causing the noise . i would just start putting back the factory parts, one by one or remove the tom's parts, untill the noise is gone. process of elimination. good luck

bitkahuna

iTrader: (20)

Hmmm... just had a thought, maybe your exhaust is hitting your rear chassis brace!?

Maybe you could have a passenger stick their head out the window as you drive around so they can pinpoint the noise a bit better.

BA_GS400

iTrader: (1)

that's a good point, several have mentioned in the past that their Toms Rear Brace either hit the exhaust pipe/muffler, or that they had to use extra washers to create clearance so that it would not hit.

Threxx

Well, it started when I installed the Daizen front and rear sway bars and poly bushings, which I did long after I installed all of the braces. The strange thing is that even after I went back to the OEM sway bars and bushings, the noise persisted. I will check the clearance with the exhaust and the rear chassis brace, though. I know I did have to use washers on the front brace because it was touching the transmission and bringing some very unpleasant vibrations into the cabin.

Adam2562

iTrader: (2)

if it happened after u installed then either a: u could also try a few extra washers on the brackets where the sway bars mount up with the bushing.. if thats the reason for the noise.. or b: depending on mileage of your car it could have stretched your sway bar link bushings and caused them to be faulty or c: which related to b: if you installed the sway bar wrong or punctured the cap of grease inthe sway ba link that would cause it too.. goodluck ... those r my opinions

bitkahuna

iTrader: (20)

I had a problem with front right corner 'clanging' going over bumps and I'll try to describe the fix. There's kind of a metal 'box' around where the sways attach and while the sways were tightly attached, the bolts holding the box in place were loose and this caused the clanging.

Adam2562

iTrader: (2)

i might try looking at this metal box ur talking about.. do you have any pics of where its located? is it near the sway bar bushing or the endlink of the swaybar.. i have this clanging noise too front and rear

Threxx

Really? Same as I described? Does it kind of sound like popping or clanging? Mine's more like a sharp 'pop' noise.

Adam2562

iTrader: (2)

mine sounds more like a loose clang hear it in the front and rear

Navaz

Check the Tom's 6-piece rear suspension bracing kit. It sounds to me that you have cracked your links. Happend to me a few years back. If that is the case you may want to replace the rear control arms because the bushings are toast.

bitkahuna

iTrader: (20)

I can't remember and never saw it first hand, sorry - the master tech explained it.