Grinding Noise at 40-60 MPH?

[guppus]

I’ve heard various complaints of a noise from the front from 40-60 MPH described as a chirping sound, a fluttering, a whine….and I have so many new noises to get used to coming from 57 years in internal combustion cars so far be it from me to join the complaints, however…….

I hear motor noise, and gear whine, and brake regeneration and can identify it and love the sounds and realize there is a symphony of motor music dynamic brake stuff going on but there is certainly a sound that joins in at about 40 that sounds like it doesn’t belong. It’s best described as a grinding, not crazy loud but about as audible as every other noise in the orchestra. Like a spun bearing noise but it doesn’t react like a spun bearing noise I’m accustomed to diagnosing like a wheel bearing that will make noise or quiet down when you turn the vehicle and load or unload it…..meaning it might be a bearing OTHER than a wheel bearing…like one for the front motor. This noise DOES vary when accelerating or dynamic breaking which is the way to load or unload those bearings so my layman diagnosis is some bearing related to the front motor.

Now, the noise may in fact be normal. My bearings might be fine. But….when I hear it (it’s always there at 40+) I can’t stop thinking bad bearing. My experience SCREAMS bad bearing and I have read about noise complaints that lead to front drive replacement in cars right off the lot brand new.

I’m concerned enough to go one day for a test drive just to check another one but felt you guys might be a better litmus test….so help my worried old school gear head ears out here…….

Is this subtle 40+ “grinding” noise normal?

 

[Ddanis60]

Yep, that’s the noise I also spoke about in the other thread. You nailed the noise description. Almost like a bad bearing fluttering in the wind, at about 40-55/60. I’ve had my truck since may. Just noticed it a week or so after the temps started to turn cold enough to have the snowflake daily here in the Midwest, which also timed right up with getting the duratrac winter tire set from Tesla put on. It’s been a few months now and as much as I swear it’s getting louder, the fact that so many people popped up with it in the other thread around the same time of year is making me feel it’s normal. Or maybe I’m lying to myself about it for my own bliss. Either way, it hasn’t seemed to affect operation that I can tell.

 

[guppus]

Yeah, no effect operationally and it never acts up or fluctuates in severity to be obviously abnormal. Might be the normal dynamic brake mechanism although brake stabs don’t directly affect the noise. Might be spun motor bearings although 5 second pushes to 60 MPH don’t make it react either.

Just can’t nail it down….and don’t know enough about what’s under me any more!

It’s just……there.

Well, there is an excellent drivetrain warrantee so at least long term monitoring is relatively safe. Glad to know I’m not alone as it adds to the “might be normal” file in my head.

It’s like my buddy used to say, “I know what that problem is, radio is not turned up enough.”

 

[HaulingAss]

When a bearing starts failing enough to make a noise it doesn't have long to go. The Cybertruck has an 8 years/Unlimited mileage powertrain warranty so I wouldn't get too concerned about subtle background sounds that you can't identify. If it were a problem, it will get bad enough that it's obvious.

Chances are, it's nothing, so just make a mental note of it and see if it progresses or stays the same.

 

[mtimmy]

My started doing it with the last update.!!! I think it is the firmware that changed something in the powertrain management system

 

[pgetty99]

Been into service twice and working very closely with a senior tech on this problem. They believe it correlates to front drive inverter at low temps. It's a tricky working theory.
I'm having my front motor replaced next week to see if it resolves. Try this: put your CT into preconditioning for supercharge. This should drive your front inverter temp over 30C which he thinks will clear the problem ( obviously not a long term solution, but indicative of the root cause). Check the attached.

Report back to this thread with findings!

 

[NormalSpeed]

How do you navigate to those screens?

 

[pgetty99]

How do you navigate to those screens?

Be. Careful! Hold the CT logo on the Software menu for 5 seconds. "service" is the pw.

 

[NormalSpeed]

Thx. And getting out of it?

 

[DrPhyzx]

...Like a spun bearing noise...

I assume you mean a bad/damaged ball or roller bearing, not a spun bearing, since an EV has no rod bearings or other plain bearings to spin.

What tires do you have?

 

[pgetty99]

Thx. And getting out of it?

Don't recall. But it's easy. In a menu somewhere, quite findable.

 

[guppus]

I assume you mean a bad/damaged ball or roller bearing, not a spun bearing, since an EV has no rod bearings or other plain bearings to spin.

What tires do you have?

Core wheels. Not tire noise.

 

[guppus]

Been into service twice and working very closely with a senior tech on this problem. They believe it correlates to front drive inverter at low temps. It's a tricky working theory.
I'm having my front motor replaced next week to see if it resolves. Try this: put your CT into preconditioning for supercharge. This should drive your front inverter temp over 30C which he thinks will clear the problem ( obviously not a long term solution, but indicative of the root cause). Check the attached.

Report back to this thread with findings!

Ok. Interesting that the suspicion lies there. Did some investigating last night and found some evidence supporting that theory.

After posting the thread and making my concern “real” I thought it was time to do some real testing. I had a long ride scheduled for last night into a precondition charge up and another long ride so I would be nice and warmed up after the errands for some testing. Ambient temp was 17 degrees Fahrenheit on a clear dry night.

First up was a common test to ICE vehicles to isolate a noise like this to drivetrain or rolling assembly by shifting into neutral at speed to see how that affects the noise. If it goes away it can be isolated to engine, transmission (ICE of course) and if it does not change its wheels, brakes, axles, driveshaft, differential, etc; That is again, for ICE vehicles.

This can be done similarly with the CT just to see what happens by using the overhead shifting controls to shift into neutral at speed…..so let’s just get it to 40 and get the noise going…….45…….50……back to be 40……nothing. No noise. Quiet and beautiful! Roll test in neutral was just as quiet. No noise?

What is different than usual right now that eliminated the noise?….lets analyze. Number 1, can’t be a bearing noise. That would almost certainly NOT be intermittent under these circumstances. But, where did it go and why?

I came to the conclusion that I seldom take rides long enough in the cold (got my CT in mid Dec so it’s always been in cold) to eliminate both the blue snowflake AND that round yellow “limited regen” symbol but noticed they were BOTH off. That stood out to me. I was on the road for hours and really had temps stabilized which for me was unusual.

This is a promising lead that I will research further and test before and after these indications go away. For the record, I always have the “use brake when auto regen is limited” off.

I’ll do another long drive heat up tonight and look for the noise periodically to see if and when it occurs or disappears.

 

[raulx]

Ok. Interesting that the suspicion lies there. Did some investigating last night and found some evidence supporting that theory.

After posting the thread and making my concern “real” I thought it was time to do some real testing. I had a long ride scheduled for last night into a precondition charge up and another long ride so I would be nice and warmed up after the errands for some testing. Ambient temp was 17 degrees Fahrenheit on a clear dry night.

First up was a common test to ICE vehicles to isolate a noise like this to drivetrain or rolling assembly by shifting into neutral at speed to see how that affects the noise. If it goes away it can be isolated to engine, transmission (ICE of course) and if it does not change its wheels, brakes, axles, driveshaft, differential, etc; That is again, for ICE vehicles.

This can be done similarly with the CT just to see what happens by using the overhead shifting controls to shift into neutral at speed…..so let’s just get it to 40 and get the noise going…….45…….50……back to be 40……nothing. No noise. Quiet and beautiful! Roll test in neutral was just as quiet. No noise?

What is different than usual right now that eliminated the noise?….lets analyze. Number 1, can’t be a bearing noise. That would almost certainly NOT be intermittent under these circumstances. But, where did it go and why?

I came to the conclusion that I seldom take rides long enough in the cold (got my CT in mid Dec so it’s always been in cold) to eliminate both the blue snowflake AND that round yellow “limited regen” symbol but noticed they were BOTH off. That stood out to me. I was on the road for hours and really had temps stabilized which for me was unusual.

This is a promising lead that I will research further and test before and after these indications go away. For the record, I always have the “use brake when auto regen is limited” off.

I’ll do another long drive heat up tonight and look for the noise periodically to see if and when it occurs or disappears.

Private citizens doing Tesla's engineer work. Amazing.

 

[raulx]

Hey admins! Block this user please! Thanks.

What for?