AWD Transmission hum at 44 mph (6th) and 36 mph (5th)
04-09-14, 08:27 PM
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AWD Transmission hum at 44 mph (6th) and 36 mph (5th)
Anyone else notice a transmission hum at 44 mph (in 6th gear) and 36 mph (in 5th) in their IS350 F Sport AWD?
The ratio of 44/36 mph is 1.22, which is also the same ratio of 6th and 5th gear ratios (0.713/0.582 = 1.22), which leads me to believe there's a harmonic frequency in one of the transmission's shafts or bearings.
Just me, or has anyone else heard this in their car?
The ratio of 44/36 mph is 1.22, which is also the same ratio of 6th and 5th gear ratios (0.713/0.582 = 1.22), which leads me to believe there's a harmonic frequency in one of the transmission's shafts or bearings.
Just me, or has anyone else heard this in their car?
04-10-14, 08:44 PM
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It only happens when the transmission is warm (e.g. after exiting the freeway), followed by driving on side roads...and its not annoyingly noticeable, but probably has as much to do with me being an audio nerd, noticing every sound out of place. 
Might just be a break in thing, it seems to be subsiding a bit (knock wood) - 1100 miles on my car as of now.
Speaking of sounds, and getting slightly off topic...The whistle some folks have heard from the driver's side mirror after having the protective film applied? Just tilt the mirror a bit - problem solved.
The creaking sound other folks have heard from around the seam to the rear left of the shifter? A dab of Teflon oil did the trick for me.
Might just be a break in thing, it seems to be subsiding a bit (knock wood) - 1100 miles on my car as of now.Speaking of sounds, and getting slightly off topic...The whistle some folks have heard from the driver's side mirror after having the protective film applied? Just tilt the mirror a bit - problem solved.
The creaking sound other folks have heard from around the seam to the rear left of the shifter? A dab of Teflon oil did the trick for me.
Last edited by IronPyrite; 04-10-14 at 09:38 PM.
04-10-14, 09:07 PM
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I think I know what you are talking about as I happen to have quite good hearing. But I thought the hum was from the transfer case, since in my case, it always happens at hwy speeds.
04-11-14, 06:21 AM
#6
I agree, not sure at what speed it occurs at, I will check next time out. I called it like a "whirring" noise. I thought maybe it was even tire noise but not sure about that.
Anyone else notice a transmission hum at 44 mph (in 6th gear) and 36 mph (in 5th) in their IS350 F Sport AWD?
The ratio of 44/36 mph is 1.22, which is also the same ratio of 6th and 5th gear ratios (0.713/0.582 = 1.22), which leads me to believe there's a harmonic frequency in one of the transmission's shafts or bearings.
Just me, or has anyone else heard this in their car?
The ratio of 44/36 mph is 1.22, which is also the same ratio of 6th and 5th gear ratios (0.713/0.582 = 1.22), which leads me to believe there's a harmonic frequency in one of the transmission's shafts or bearings.
Just me, or has anyone else heard this in their car?
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