Roaring Sound Inside Cabin
#16
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No pulsation. It seems to start at 25-30 but you can hear it slower upon decel. I do not believe it is rotor or caliper related. Brakes were good last time I had the wheels off and the pedal doesn't pulse. Nothing in the steering either.
#17
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#18
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#19
Lexus Test Driver
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I think you'll find (eventually) that the growl/roaring noise is naturally coming internally from the AWD transfer case and transmitted via some mounting/support bushing or component directly or indirectly associated with the transfer case which has become either hardened or deteriorated - allowing the noise to be transmitted to the frame instead of isolating the noise from the frame to reduce the noise from being heard inside the cabin. That said, I doubt there is anything wrong with the internals of the transfer case. I also rather doubt a worn or defective axle/wheel bearing is causing the growl or roaring noise.
#20
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I think you'll find (eventually) that the growl/roaring noise is naturally coming internally from the AWD transfer case and transmitted via some mounting/support bushing or component directly or indirectly associated with the transfer case which has become either hardened or deteriorated - allowing the noise to be transmitted to the frame instead of isolating the noise from the frame to reduce the noise from being heard inside the cabin. That said, I doubt there is anything wrong with the internals of the transfer case. I also rather doubt a worn or defective axle/wheel bearing is causing the growl or roaring noise.
I may stick my cheapo GoPro knock-off under there to see if anything can be narrowed down.
#21
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Until I crawl up under it, I'm going to go with this assumption as well. It isn't louder with the windows down at any corner and appears to be emanating from the middle of the car when sitting in either front seat. Best I remember, the rear wheel bearing was pretty loud and pretty obvious in turns.
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Last edited by bclexus; 10-02-21 at 03:07 AM.
#22
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Until I crawl up under it, I'm going to go with this assumption as well. It isn't louder with the windows down at any corner and appears to be emanating from the middle of the car when sitting in either front seat. Best I remember, the rear wheel bearing was pretty loud and pretty obvious in turns.
I may stick my cheapo GoPro knock-off under there to see if anything can be narrowed down.
I may stick my cheapo GoPro knock-off under there to see if anything can be narrowed down.
#23
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#24
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As previously mentioned, I think the natural noise generated by the AWD transfer case is being transmitted to the car's frame via a failed (hardened or deteriorated) mounting bushing, its purpose being to isolate the transfer case noise from the frame.
#25
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Here is an audio recording where my phone was laying on top of the hump for the transfer case. You can hear the engine and when I let off, the roar is more prominent. You can barely hear me say 30MPH and 40MPH since this is basically under my knee. I slow down and then accelerate again.
Hopefully, this works. It is shared from my Google Drive.
Audio of Roar
Hopefully, this works. It is shared from my Google Drive.
Audio of Roar
#26
Lexus Test Driver
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Here is an audio recording where my phone was laying on top of the hump for the transfer case. You can hear the engine and when I let off, the roar is more prominent. You can barely hear me say 30MPH and 40MPH since this is basically under my knee. I slow down and then accelerate again.
Hopefully, this works. It is shared from my Google Drive.
Audio of Roar
Hopefully, this works. It is shared from my Google Drive.
Audio of Roar
#27
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Listening very carefully, it sounds similar to what a manual transmission with a degree of gear drive lash (intentional play, slop or clearance between gear sets) sounds like when going from an unloaded (i.e coasting) condition to a loaded (i.e. under a degree of acceleration) condition. All pretty typical... I'd look for a failed bushing that (when undamaged) is intended to absorb or prevent that gear drive noise from being transmitted to the frame and inside the cabin.
I will get it on the lift this week and check it out hopefully.
#28
Lexus Test Driver
#29
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easy way to rule out a wheel bearing is to get a laser thermometer and after a 10 min steady drive down the highway jump out and check all four corners for hub temps. Tires also wear in different patterns to create road noise that would be speed dependent. Check differentials as well but those usually create a whining noise so there is always that. My guess would be a wheel bearing even though you think its not, because the symptoms you have explained are all pointing that direction even though your tests didnt point that direction. When i was test driving GS's before i bought my 15, i drove a 13 AWD and it made a low whine and very suttle floor vibration from about 40mph and below. Grab a laser temp guage off amazon which dont cost that much as they used to and check to see if you can spot an anomaly.
Further up the rotor where the pads run, they were all well over 140° but still within a nominal range so no calipers sticking.
I'm procrastinating and dreaming up other projects to avoid putting it on the lift. I'm actually waiting for a buddy to drop by so I can do it without involving my wife. She tends to abhor anything car related.
#30
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I don't know if you have already done this, but I would drain and refill the diff and front transfer case fluid also. Listening to the recording it sounds like 100% drivetrain, front and/or transfer case, rear diff??? I did notice a little shake on the dash? Is that the car or just the recording device shaking? My guess is front transfer diff, or rear diff. This is strange, cause it also had the drive axel wheel bearing type noise also. ppl have already been replacing wheel bearing on these 4th Gen GS's. I think to nail it down you may have to lift the car, let someone put in gear carefully and accelerate to listen and pin point where its coming from.