ComradeJoe

Good day everyone,

I have a 2001 LS430 that I purchased last October that has developed a loud vibration I was hoping to have some help with on diagnosing. The sound would be best described as a leaky exhaust at low speeds and a rumble/hum at higher speeds. The sound and vibrations become noticeable around 25 and can cause nausea at 40-50. They continue beyond that speed but tend to get a bit quieter. I can't place my finger on where the sound it coming from due to it making the whole car vibrate. To me it sounds like the rear, to my wife it sounds like the front. I've also noticed that the vibration/noise seems to get a little better going around a big sweeping corner at speed. The sound seems to be exclusively linked to speed. I've watched the tachometer for shift points and noticed no change in sounds and I also don't feel any vibrations coming up through the brake pedal as I break.

About 7k miles ago I replaced my pads, rotors, and caliper bolts, I can't recall if the sound/vibration was there before doing this work due to how bad the brakes sounded. The rear brake pads were pretty much gone and the rear rotors have developed a few spots where the pads weren't hitting. I'm live close enough to country roads I was able to preform the manufacturers recommended break in/bedding procedure after the replacement.

In the past few weeks I also got a flat tire which resulted in me replacing my rear two tires. The front tires still had plenty of tread left or I would have just replaced all four. The sound was present prior to the new tires, that I know for sure because I was assuming the sound was coming from my spare tire which didn't match the other three.

This last weekend thinking maybe it was a wheel bearing I lifted each wheel individually and did the wiggle test but didn't get any play in the rear two wheels, I got a little play at 6 and 9 on both the front tires but I've been chalking that up to tie rods needing replaced. I'm in the process of saving up the money to refresh the front end at the moment.

My thinking so far is that since the issue is tied to my speed it has to be something that's rotating. That leaves me with something happening at one of the wheels of the driveshaft/differential.

I'm hoping it's just a tire that's way out of balance but knowing my luck it will likely be something worse. If anyone has any idea of what it may be or anything else I could check I would greatly appreciate it.

Thank you!

BCT

Agree with ^

I would start with tires and wheels. Move the left (or right) front wheel to the back, back to the front. Does the sound and vibration moves/change? Then move the other side. If still the same, my guess would be wheel bearing or perhaps your brake is dragging. How many miles that your car has?

Mbodall

Is the sound completely absent until you reach 25? Or is it there, but not super noticeable until you reach 25? Can you take a recording of this by recording a video with a smart phone, then post it on YouTube and share that link here?


Does it "get a little better" going around both left and right-hand sweeping corners? Or only one or the other?
You say the vibration is can't be felt through the brake pedal... what about the steering wheel? Or the shifter?


What do you mean by the rear rotors developing a few spots where the pads weren't hitting them? Like grooves that go all the way around the rotor? Or intermittent spots around the rotor like the rear rotor was bent/warped and the pads were skipping along the rotor? And is it still like that now? Or is that just what it looked like before you replaced the rear brakes?


When you had each tire up in the air, did you spin the wheels at all to see if you could hear or feel any grinding or friction, or any other sounds?
If not, I'd do that to see what you can hear and feel. Spin each tire quickly and see if each wheel/tire is spinning smoothly/symmetrically and isn't wobbling or anything. Then spin each one slowly and see if it seems to slow down or stop spinning at some point in the rotation.
For the back wheels, I'd either take two jack and jack stands, or one jack in the middle with two jack stands, and lift both rear tires off the ground at the same time. Then have your wife or someone else get in and start the car, press your "VSC OFF" button right in front of the shifter to turn off traction control, then put the car in drive and let the back wheels start spinning at idle. See if you can hear or feel anything from the driveshaft bearings or u-joints, rear differential, or wheel bearings. If nothing's obviously making noise/vibration, have your wife/helper gas it up to 25mph and check again.

From the sounds of it, I'd have to agree with you. Have you checked to see if the sound changes at all under load/acceleration vs coasting? Does it sound exactly the same at 55 coasting on flat land/downhill as it does going 55 and giving it power up the hill?


From what you've described, I'm going to say it's not just an out of balance tire. Out of balance tires don't sound like exhaust leaks at low speed. If it's tire related, then it would have to be a seriously defective tire that's having the belt or tread separate, or something far more serious like that. One way to eliminate the tires as a possibility is to swap each tire out with your spare and go for a drive. If the problem magically goes away, then you know it's whatever tire isn't on your car at that time.

ComradeJoe

It feels like it's there but since I'm not at speed it isn't as bad. I'll take a recording on my way home tonight and upload it when I get home.


I can't say for sure, the only corner I take is a left hand turn at 45 which is when I noticed it the sound lessened. I'll turn around and take it the opposite direction tonight and find out for sure.


There was a spot or two on my rear passenger wheel, probably about the size of a quarter, where the pads were skipping along the rotor. When I pulled the pads out of the back the pad material basically disintegrated from rust(yay ohio!) I also didn't noticed any uneven rear on those rear pads, but as I said the pad material on both was basically gone.
I have been keeping my eye on those back breaks for signs of uneven wear and so far they look good.




I didn't rotate the tires when I had each of them up in the air. I'll should be able to check the fronts tonight but I may not be able to get the back set up for that until this weekend. That's a great idea though.

I've tried to notice a difference in acceleration/coasting but couldn't come to a definite answer but I'd lean towards no. There is a change in sound but it's minimal and I can't say if its just due to the change in speeds. My wife's Jeep recently had a bad u-joint and this isn't as obvious of a change as that was. That would vibrate a lot more and only when I took my foot of the gas. My Lexus vibrates and generates the sound regardless constantly.


Just as BCT suggested I think this is going to be my next course of action. Hopefully it is just a tire but it will be good to know for sure.

My LS430 has 159K on it, and I should also note that I have put it in neutral and revved the engine briefly up to 2k and didn't hear the sound just to rule out exhaust problems.

Mbodall

Awesome. That should help narrow it down.


This puzzles me. It's very strange to have what appears to be evidence of a pad skipping across the surface of a rotor, as well as the pad material disintegrating in your hand. If the pad material disintegrated when you touched it, that makes me think that the pads weren't even coming in contact with the rotors under braking, otherwise the rotor would have just obliterated the pad when the caliper piston pushed it into the rotor. Also, I know rotors get rusty, even after just a day or two of not being driven, but a rusty pad? That's weird.

When you did the brakes, was there visible rust on the rotor? If there was and it was covering most of the surface of the rotor, that would suggest that one of the pistons is probably seized and not pushing that pad into the rotor. After installing the new pads in the calipers, did you have to push the pistons back into the caliper so that the rotor fit between the pads? If so, did both pistons go freely back into the caliper? And lastly, did you replace the rear rotors? If not, did you bring them somewhere to have them resurfaced?

ComradeJoe

When I did the brakes because of that one wheel I decided to just go ahead and replace all four rotors and pads. That rotor specifically had evidence of rust even after my 50 minute drive to work which should be enough to grind down any surface rust that would have formed over night. The car is also garage kept. You're absolutely right it is weird and worrying to me that's why I've been doing a quick visual check when loading my work bag into my car just to see if that wheel develops that same wear pattern on that rotor. I was concerned that caliper might be bad, but I haven't seen any signs let of that.

I did have to reset the position of both pistons on that caliper and all the others before putting the pads in. I can't say I recall having any abnormal resistance from that caliper specifically, and if memory serves me I don't recall there being any massively uneven wear between either pad on that caliper. From what I remember both piston's went back in easily. I already scrapped those pads and rotors of I could take a picture of them. I'd say that the fronts were at about 75% and the rears were 98% gone which is why when I pulled them out the remaining pad material just crumbled.

Mbodall

Is it possible that the spots on the rear rotors that you mentioned weren't actually discoloration spots from heat? Were the spots a different color? What exactly did you see that made you think the pads weren't making contact with the rotors in those areas? And just for further clarification, do you mean that these spots were like a low/thin point in the rotor, and the pads never made contact with these one or two areas? Or just that it appeared the pad was skipping/jumping across the rotor, and this skipping was occurring along different parts of the rotor?

ComradeJoe

The spots on the rotors appeared to be low spots they were discolored brown and felt rough to the touch, They didn't appear like this type of heat spot, they looked much more like this image.

Also last night I started doing some of the trouble shooting you recommended and took some photos of my current rear rotors while I was at it. I don't see any signs that either or the rears are sticking so I'm assuming the rotor issues were my fault for waiting to long to replace the rear pads after I purchased it.





Driver Rear Bottom


Driver Rear Top


Passenger Rear Bottom


Passenger Rear Top


I ended up swapping in my spare to both the passenger and driver rear with no change in sound. I also jacked up each front tire individually and gave them a spin, both spun freely without any wobble and didn't appear to hit any sticking points.

I also went ahead and recorded a video of the sound the car is making going from and did a sweeping right hand turn test you asked for. The right hand turn didn't cause a change in sound so I did some swerving (safely) going down the road and confirmed that it sounds like a swerve to the left at speed reduces the sound/vibrations but a swerve to the right does not. This has me leaning more towards a wheel bearing, likely in the rear. Looks like my next course of action will be to do as you suggested and jack up the rear and give the tires a spin to see which one is causing the issue.If you have any other ideas though I'm still open to them, I know I'm more often wrong about these things then I am right.

Mbodall

ComradeJoe

Finally managed to get some time to get the rear end in the air and discovered that at the very least my drivers side wheel bearing is bad. Hopefully that's all that wrong. It's weird I've never had a bad wheel bearing make that much noise without some wobble. I've got the bearing on order and I'm planning on replacing it this weekend. Hopefully all goes well!

Mbodall

Yeah no kidding. I've never heard a wheel bearing make that much sound and vibration. Let us know what happens.