Question about vehicle noise

[kgb]

Hi,

I've had a noise (whir or hum) coming from my 2010 Roadster Sport 2.5 for a few months now. I can't tell if it was always there since delivery, and I am just noticing it, or if it is something new. So I am posting a description to see if other have this sound. Roll Call (Yea or Nay): When cruising on smooth pavement, I notice a whir, whine, or hum that is maximally noticeable between 40-45 mph. It is definitely audible at other speeds, but, IMO it is the dominant sound at those speeds. At 40 mph, I don't get wind intrusion noise, and I don't get the engine "turbine" sound. This sound varies in volume and pitch with speed, and it seems to be resonant at around 40 mph. I initially attributed this sound to tire noise, but now I am not too sure... I think it may be more mechanical than I initially thought. Coincidentally, I noticed this noise around the same time I started complaining about the weak air-conditioning, so there is a good chance those two things are related. I am thinking of bringing it up with my Ranger, but before I do, I wanted to get a sense of the urgency. If many others have this sound, then I'd save it for the next routine visit, but if I'm the only one, I was going to make a call.

Thanks for your input.

P.S. When I say it is related to the A/C, I don't mean caused by the A/C... just in some way related. Perhaps a worn bushing or something that would cause a resonant vibrating hum/whir... (I'm having a hard time describing it, feel free to suggest adjectives, I will use them if they help)... but I think it is more of a hum... :wink:

 

[S-2000 Roadster]

I've noticed that heavy acceleration and heavy regenerative braking cause a much louder noise than just cruising at a steady speed. I figure this is bearing noise or gear noise caused by the load. What you describe doesn't seem to match what I'm hearing.

I did turn my A/C on the other day and it seemed to make more noise. I turned it off, paused for a while for the noise to go away, then later turned it on again and heard nothing that I recall.

Anyway, I suppose it's hard to estimate without actually hearing the sound.

 

[kgb]

Anyway, I suppose it's hard to estimate without actually hearing the sound.

I'll see what I can do about recording it and posting a video/audio.

The noise is most prominent when traveling at a constant speed, because it allows the sound to resonate. Today, I tried it again, but with the A/C off. Whether the A/C is on or off has no effect on the hum. As I said before, it's not the A/C, but I wonder if running the A/C caused something to come loose. But now that I have listened more closely, I think that the tires are making a hum, and that the pitch of the hum resonates with the interior volume of the cabin almost exactly between 38-44 mph. Usually, I have the radio on very loud in my car in order to drown out the wind noise, but when I slow down, I find the radio is too loud. It is only when I turn down the radio that I notice this sound. The reason I missed it for so many months is that I need 3 factors for it to happen: (1) Smooth road, (2) Radio low, (3) travel for a while at 40 mph. Because it resonates, it becomes deafening when I keep those 3 factors going for a while. At this point, I am pretty sure that it is tire noise, so does anyone else have this effect on smooth road at approx 40 mph?

 

[Mycroft]

Try experimenting with different driving surfaces. Find a road with brand new asphalt and a road with concrete paving.

 

[Doug_G]

You sure it's not gearbox noise? It makes a couple of different "notes", and different notes are more prominent depending on your current speed and acceleration.

 

[kgb]

Not sure if it will record well, but I will use my iPhone to capture the noise and post it. Sadly this is a busy week for me, so it might be a while.

 

[S-2000 Roadster]

Which tires do you have? Tesla Motors provides at least a couple of options, plus the winter tires. It's a well-known fact that performance tires make more noise; they're also more pitched than standard tires. I ran Bridgestone RE-71 tires until they wore out, and they had a very distinctive resonance.

 

[dwegmull]

Which tires do you have? Tesla Motors provides at least a couple of options, plus the winter tires. It's a well-known fact that performance tires make more noise; they're also more pitched than standard tires. I ran Bridgestone RE-71 tires until they wore out, and they had a very distinctive resonance.

Some tires also get noisier as they "age". This is long before getting to the wear bars which create their own distinctive noise. My original, non-sport tires, started getting louder after about 7000~8000 miles. They are not at the wear bars yet (I will probably have the rear ones changed in December during my annual service).

 

[efxjim]

I have also noticed a hum that seems to be getting louder. It is about 2000 and 4000 rpm on the motor (multiple resonance?). It is felt through the steering wheel and heard in the body. I would guess it to be bearing noise. I have newer toyo 888 tires that are pretty quiet. Mileage is about 12,000. Any one else?

 

[Talkredius]

I have Michelin tires with energy saving profile. Looks as if this causes some noise and some vibration on brand new asphalt if I accelerate very slowly (2... 5kWh). At the service station in Munich they checked it and used a different pair of tires, the noise was gone with these tires.

 

[kgb]

Here is the sound sample I promised. 2 things: 1) don't listen through your computer speakers, it doesn't do it justice. I listened through my speakers, and I could barely hear it. 2) Listen to it with headphones, and you'll hear it. If you are wondering why I am making a big deal about it, TURN UP THE VOLUME. In the car, it is much louder! The iPhone mic really did capture the resonation.

Don't be fooled by the sound 0:14-0:30, although that sounds louder on the video, it must be a function of the iPhone mic, the sound is heard at 0:38-0:49 is what resonated in the car and is perceived as much louder.

So, what do you think it is? I have the Ranger coming to fix the A/C, should I mention this?

 

[TEG]

Random guesses:

• Burr in one of the gears in your gearbox?
• Wheel bearing issue?

Any way to narrow down a direction? Is it coming from behind you?

 

[SByer]

Mention it. And let him listen to the video (yeah, I know...). It could be just cupping of the tires or something, but with a sound like that (and it was definitely an extra harmonic from what I hear), there is no substitute for experience.

 

[NigelM]

I hesitate to make a guess, but I can say that it isn't something I have heard in my 2.5. Seeing as it seems to be a regularly occurring noise in your car, isn't it easier to take the Ranger for a ride rather than playing him a recording?

 

[kgb]

I am so embarrassed. Can we take down this thread now?

I had checked for wear lines on my tires a short while back... coincidentally, just before the noise was obvious. I then noticed the noise and immediately ruled out the tires, because I had checked them for wear lines. What I didn't do is check for tread depth. I also didn't check for wear after I heard the sound. When the Ranger was here, I asked him about the sound. He agreed that it was loud. He looked at the tires, and lo and behold, the wear lines were visible. I changed the tires, and the sound is gone.

I am admitting my stupidity to be sure that blame is placed where it is due... with me. I will also be updating the tire thread.

 

[S-2000 Roadster]

Hey, don't feel bad - it's an honest mistake. Maybe this thread will still be educational for the next owner who ends up in the same situation.

 

[Alan]

Totally agree, nothing to be embarrassed about. Not all tyres have wear bars and not all tyres wear out as fast as those on the Tesla so lots of owners are going to hit the same problem. Your posts will save others a lot of hassle / worry.

 

[bonnie]

kgb - huge respect from me for posting the outcome - not everyone would have done that.