SC95

Hey everyone,

I'm not normally the type to post issues on any of the automotive forums I'm on since I am typically able to research, troubleshoot, and solve without doing so, but this one has me stumped. I've read and read and done quite a bit of troubleshooting and part replacement to try to cure this pop issue, but to no avail. What is strange is that it is inconsistent and doesn't happen over every bump (though it does consistently happen over certain ones, specifically those in the video below) and seems to be alleviated for a short period of time after the car has been jacked up and then dropped back to the ground (i.e. when replacing front suspension components). Instead of me trying to explain the noise I am hearing, I compiled a bit of my dash cam footage from my commute today to illustrate the issue and posted it here:


I captioned in the video when each pop happens, so you should be able to make it out, especially if you are wearing headphones. It should be said that the sound is a fair bit louder in person than the video suggests.

As far as parts that I've replaced, here is the list (all within the last year and a half):

- Steering Rack (incl. ITREs) and bushings (Unsure of brand, original owner had replaced by reputable independent shop before my purchase)
- Outer Tie Rods (OEM)
- LBJs (OEM)
- Lower Control Arm No. 2 (a.k.a. caster arm, OEM)
- Sway bar bushings (Prothane)
- Sway bar endlinks (Moog)
- Struts and Springs (KYB Excel-G / NF210; reused strut mounts, coil isolators and bump stops)
- Brake pads, fit kit, shims, guide pins, and guide pin boots (OEM)

All suspension-related hardware as well as that for the front subframe and chassis brace is tight and torqued to spec, so no issues there, hence why I am stumped. Please let me know if any of you have any input as to what could be causing this noise, as it has been aggravating me for a few months now and I haven't been able to nail it down yet. I have no problem purchasing and installing whatever parts are necessary to fix the issue, but I am tired of throwing money at the issue, and more importantly, spending quite a bit of time on installing components that have not fixed the problem.

Thanks in advance for any help you all can provide!

shwalker07

Your list sounds exactly like my list of things I have replaced recently. I have the popping sound as well but not as bad as yours as mine is more quiet and mostly when I am pulling into my driveway which is on a steep angle (driveway is 2.5ft higher than the street in about 5ft length of driveway for the angle). I been in a vehicle with a bad upper strut mount and it almost seems like the same sound since it happens over bumps. I am also wondering if one of the two pistons in the front brake caliper is sticking and not releasing the brake pad when it should even though everything is greased properly and nothing seems to be binding up. It is just wired as it just pop's once and not like two pop's meaning something is moving back and fourth.

I have to try this myself but if you are on a longer bumpy road, apply the brakes one hard time to a stop and do not apply them again and continue on the bumpy road, do you hear a popping sound only once or do you still hear it multiple times without touching the brakes?

Blaze876

iTrader: (1)

Just going from my own experience, I had a similar popping issue and it was the caster arm Bolt kept getting loose. When I mean loose, it got loose probably a half turn it so. I said **** it and used a breaker bar and tightened it with I would estimate over 200 pound feet of torque.

MedicalDoc

Loosen the 4 nuts that hold ur strut up top. Loosen the lower strut-lca nut almost completely. Jack up car. Torque the upper strut nuts,i.e., 20 ftlb and 47 ftlb. Lower car and bounce that corner several times. Jack up car and hand tighten the lower nut. Lower car and torque to spec.
What this ensures is that you have no torsional tension.

JL004

I had the exact same sound. Initially it was only on the right side then the left started making the same sound too. The culprit in both cases was my front upper ball joint. Replaced both front upper control arms with Moog units, sound gone.

Mr Jokster

iTrader: (8)

Thats where you messed up... Most likely the strut mounts. Everything replaced could have and should have been inspected to narrow down the exact issue. I'd like to believe its the mounts. I'm on my bi-yearly front-end overhaul and currently in the same predicament. Unfortunately, I've got retarded expensive custom mounts on top for the bags and didnt want to believe those are the culprit. I'm yet to inspect the rubbers.

Mackd1418

Lol glad I seen a post with the same problem, I changed pretty much all the parts you changed minus the mounts, after a week of installing I started getting these pops, I researched and thought it was the slider pins in the brakes sticking, checked that out cleaned slider pins and all, still get the same noise. I didnt wanna post asking anything cause they be quick to tell you to do research. I will be trying all that was suggested in the post.

SC95

Just ran some "tests" during my commute, and the issue is definitely brake independent in my case. It will pop multiple times without touching the brakes, and I am able to reproduce the pop with some consistency by jacking the car up and/or bouncing the front end with it on the ground (obviously, no brakes applied during this scenario). Still haven't narrowed it down at this point, but I will be investigating further as I have time this week.

SC95

I've checked the caster arm nuts and they are most definitely tight and torqued to spec. When I went through checking all of the bolts this past weekend that was one set on my list.


I will look into this procedure - I am familiar with the torquing sequence other suspension systems use to ensure that there is no improper preload on any components, but I don't remember exactly what procedure I followed when I replaced the struts and springs, so a re-torque can't hurt.


That was one of my initial thoughts for the cause of my issue as well, but I had checked them before and just re-checked a few minutes ago, and they have absolutely no play. I wish it were the upper ball joints, since the UCAs are fairly easy to replace.


I actually had the mounts and the rest of the ancillary wear items on order when I did the struts, but they ended up being delayed at the time so I moved forward with the job without them. As I was inspecting the coilover assemblies tonight, however, I noticed that the spring isolator/dust boot combo has split on the passenger side (the side that is popping), which I can certainly see as a potential source for the noise if the coil spring is undergoing torsional movement and popping due to the lack of any meaningful substance to the coil isolators in the places where it has split. At this point, I can't leave the isolator split even if it's a non-issue (OCD), so I will go ahead and replace those, the bump stops, and strut mounts once the order I just placed for the bump stops (also just splitting) comes in.

I snapped a couple quick photos of what I'm talking about just for reference if anyone is curious about what to look for if they suspect they have a bad isolator - the first two with the arrows are of the split one with the arrows pointing to the splits on both sides, and the third is of the driver's side isolator, which is good.








My issue started almost a year after installing all of the components I listed other than the brake overhaul and sway bar parts, so definitely more of a delay than yours, but I will definitely keep this thread updated with what I try and what (hopefully) solves the problem eventually.




Also, just to add a bit more information and context that I forgot in the OP, the pop only occurs on the passenger side, typically on suspension droop but occasionally on compression as well. Also, for what it's worth, the car has a bit under 110k miles.

SC95

Just wanted to post an update to this so it can hopefully help somebody in the future; the pop issue is now solved. I replaced every front strut component that I had not replaced previously (mounts, isolators, etc) in order to fix the split coil isolators, and had no change in the issue. At that point, I decided I was tired of playing parts darts, and got the car up off the ground high enough to do some proper investigation. I found two areas that my local Lexus dealer touched in the past that needed attention: all transmission crossmember and mount hardware was not torqued properly (removed by the dealership to reseal the transmission pan as per invoices from the original owner), and I also found the eccentric bolts on the front lower control arms not torqued properly as well (adjusted by the dealership about 6 months ago when I had them perform an alignment). I torqued all of the aforementioned bolts to spec, and the issue is resolved at this point.

If you have a pop sound like is shown in the video in my OP, definitely check those places as part of your diagnostic process, especially if the transmission pan has been dropped in the past or if you have recently had an alignment. Hope this info helps somebody; now it's time to get back to modding!

MedicalDoc

Congrats, SC95. I am sure u r a happy camper after getting this resolved!
It is a shame that some Lexus dealerships do not pursuit perfection, specially with what they charge. It really does not inspire any confidence if as a customer u have to check the work they said they did.

badblackgs

iTrader: (1)

good job updating. people usually dont do that. they ask for help, argue, than never respond when they figure it out.

MedicalDoc

I will second, third and fourth that!!