Suspension noise diagnosis

[ZHPizza]

Drive with the rear seats down and you'll know if it's coming from the rear. There's very little sound deadening in the trunk area.

[nsk040]

Good call on putting rear seats down. That experiment only gave me more confidence that the noise is coming from the front. Anything left up front besides tie rods and sway bar bushings?

[holyc0w]

Does the noise occur during braking, turning, acceleration, steady speed?

[nsk040]

Does the noise occur during braking, turning, acceleration, steady speed?

I tend to hear the noise (may actually be two distinct noises) driving down rougher paved roads at ~20mph. These roads don't have potholes, probably best described as having been excavated before for sewer or whatever and then repaved...and the repaved spots create indentations or humps. Car is basically static as it goes over this road...i.e. no turn/brake/acceleration.

On a smooth road, I can't reproduce any noise by getting on the brakes hard or aggressive steering inputs. My steering feels like new on on ramps so I'm not thinking tie rods or guibo are the issue.

Are tie rods and sway bar bushings (only 2 things left to replace) good for well beyond the 110k miles I have on the car? As replacing the sway bar end links didn't really seem to accomplish anything I'm hesitant to continue replacing stuff w/o a good reason to.

[nsk040]

At this point the entire suspension is new, yet the noise remains.

I'm thinking the noise is related to a little movement from something heavy. Likely mounts for the transmission or the diff. It could be engine mounts, but there is zero vibration so these are probably fine.

[Sockethead]

Don't rule out motor mounts. You should check them.
Also, I've had the OEM LCAB fail at 40k. So you might want to check them... If I read right, you didn't replace them this time around?
Recheck you swaybar end links for tightness. When you jack up just one side of the car, you are preloading the end link so it will appear to be tight even if it's a little loose.
Check mounting bolts on engine mounts, steering rack and subframe. Little chance they're loose but when hunting down a noise, you need to eliminate

I read through real quick, did you replace your top strut mounts? That could also cause the noise you are describing. Again they will be preloaded by the weight of the suspension when jacked up. Jack up the car so the tire is only a couple of inches off the ground. Use a big pry bar to lift the tire/suspension up and check for play. Even a little bit of play here will make noise because the strut tower will act like an amplifier.
The reinforcement plates are just sheet metal they won't change ride height.

You mentioned one of your rear lower control arms is bent. That usually happens when the car is towed. The tow truck driver puts the J hook there because it's convenient but it ends up bending them because they weren't designed for that kind of load.

Also, did you check the rear diff mount when doing the rear suspension ? They are notorious for failing. Not related to front end noise but probably needs to be addressed

[nsk040]

Thanks - really appreciate all the info. Trying to respond in order.

LCABs are original. RTABs new. Swaybars have been checked w/ no preload. Tie rods new/checked...though perhaps steering rack could have some internal noise?

Need to get car on lift to check subframe, motor, diff, and transmission mounts.

Shocks/struts all new with new mounts and reinforcement plates.

Very slight bend in lower right control arm. Had an alignment last week and they were able to get it to spec. Car has never been towed, so no clue how that got bent but can't see it being related to the any noise.

[Sockethead]

No, I was just mentioning the bent arm as FYI.
If the LCABs are original, I'd start there. They are fluid filled. If there is any brown around that area, the fluid has leaked out... Mine we shot with only 44K original miles on the car... probably replaced them 3 or 4 times since then... I have 143k on the car now.

If the rear diff mount is shot, it will be easy to tell by prying with a pry bar. If it's torn (usually the first thing that happens) you'll have to physically eyeball the rubber while prying...

[nsk040]

The noise is clearly coming from the front so not likely LCABs.

Had a shop get the car in the air. Engine mounts, transmission mounts, diff mounts are all good.

Their only idea was that one of the new struts was somehow misaligned, however this was only a theory as everything looked good from top and bottom (but we didn't actually take the strut out to confirm). I have trouble believing that the struts were not installed/torqued correctly.

Back to square 1.

[Sockethead]

If you installed Koni yellow struts, there is no nub on the shock body to line it up properly in the steering knuckle. It's easy to get it misaligned. I did it myself the first time I installed them.