I8ABMR

Hey guys I have noticed a very mild cyclical humming noise at exactly 70 mph. Initially I thought it was the original Bridgestones but it continued after I had a new set of Michelin PSS mounted. The noise can only be heard if the car is on a smooth road and the radio and AC are off. I was wondering if anyone else has or had had this issue. I was wondering if it may be a wheel bearing or issue with the differential. Not sure. Its not a big deal but would like to get to the bottom of it if possible.

The car is going n for 30k service this week and I will bring it up but was wondering if I can get any more info on this. I have a feeling the dealer will tell me that they cant hear it.

itsmike177

iTrader: (3)

Interesting, I thought it was the tires I have too. 2011 ISF here, ~33k miles. PSS tires that have probably 5k miles remaining...

I noticed the "cyclical hum" on at highway speeds too and thought it was due to the tires... but you got me thinking it's not....

Anyone else have any ideas?

I8ABMR

I wonder if it is the tires still . The fact that its cyclical means something is going in and out of phase. usually means there are multiple sources that are falling in phase. Not sure. Its subtle that its hard to hear unless the road surface is very smooth.

Its odd because there is no vibration. Its just the humming

this has " can not diagnose or reproduce" all over it

Rickna

iTrader: (3)

I'm wondering if it has anything to do with the pavement. Here in New England we have notoriously horrible roads. The newer asphalt pavement is quieter than old worn grainy pavement. Concrete is wavy and very noisy. Just a thought...

I8ABMR

I have a feeling that, like the belt slip noise, that this is a lot more common than most think. I just think that the roads here are so smooth that you can hear any and everything.

ChiroBLD

I still think it's your tires. I have the same problem ever since I installed PSS's recently on my 07' IS350 at around 70-75mph-- a low hum that cycles. You can "hear" it in the car and feel it slightly. It doesn't occur at all below these speeds. Feels like they are out of balance so was planning on taking it in to have them rebalanced to see if that will take care of it.
Never had the problem before with any other tires on this car driving the same roads. Weird, hope it's not a PSS problem as I swear by Michelin's.
My 08' ISF still has the original PS2's and they are perfect at any speed.

I8ABMR

What's got me confused is that the same noise was happening with the Bridgestone RE05A. I assumed it was the tires and since the tires were going to be replaced with Michelins I didn't think about it . It's still happening so I was wondering if it's the car or the tires . The issue is that I am EXTREMELY sensitive . Usually more than more service techs. I mentioned it in passing today at service but the tech said its probably the tires. Since thy got me in mat second and its nothing major I will take them for a ride next time .

lobuxracer

iTrader: (2)

Put 18's on it and it will likely disappear. Short sidewalls are noisy.

I8ABMR

Thanks buddy. I was waiting for you to chime in with you expertise. Its not crazy but its there. I just turn on the radio and its not noticeable. Who the hell drives with the radio off anyway. LOL

Just wanted to make sure it wasnt something with a wheel bearing or diff.

lobuxracer

iTrader: (2)

That would be me. I like to hear what the car is telling me so I have the jump on any issues. I also love the sound of the V-8.

I8ABMR

ok you got me buddy. Thanks for the help though. Just literally picked up the car and she feels great.

I8ABMR

UPDATE !!!

Just picked up the car after the major 30k service. The differential was serviced and now the car is as silent as my LS460 when crusing on a very smooth road. I am confident it had something to do with either the differential .......or something that was serviced .....obviously.

itsmike177

iTrader: (3)

I replaced the diff fluid 3k miles ago and the humming noise is present before and after.

I8ABMR

damn it !! Just checked it again and the noise is still there but much reduced. I have to really try to hear it and need to turn off the radio and AC . I am assuming its the tires then. Not sure, but had a 31 month vibration issue with my LS that was solved with tires. This little noise has " can not fix" written all over it . I can only imagine the look on the SA and techs face if I tried to get them to Dx this

Eurofreak

Very old thread, I know, but did this ever get figured out? I got new tires and feel like I am also getting a low frequency rhythmic humming at 80mph that gets louder with speed.