Join The Community

Name that noise? "Thunk"

Over the past few weeks my loaded 85 with 9000k miles has developed a rather loud metal on metal "THUNK" noise. It is emitted from the rear at low speed when the accelerator is released and the regen kicks in. Also when I step back on the accelerator and disengage the caliper.

Wheel Bearing?
Loosely mounted wheel?

It started after getting it back form the Santa Monica service center - Supposedly the tires were rotated and balanced.
Its going to the new Van Nuys service center on Tues.

Any ideas?

Sounds like motor mounts to me.

Metal on metal would "clank," not "thunk."

Anything rolling around in the footwell area, or the small pockets to the sides of the footwell? Maybe some old parts or a hand tool were left behind?

Is the rear hatch closing tight? To quote from this old thread:

"If you open the rear hatch you will find two thumb screw type rubber dampers on each side of the hatch by the edge (not the solid plates they press against on the car itself). If the screws are not far enough out the hatch acts as a large speaker bouncing up and down as you drive over uneven roads creating this uncomfortable pressure feeling. Adjust them out far enough so the hatch closes tightly but not too far where the automatic closer will not shut because there is too much pressure. This adjustment, in combination with the rear parcel shelf to absorb vibration, greatly reduces the pressure buffeting problem."

Do you know where your adapters are - that was the cause of my thunks.

I don't believe there is a regen caliper. The two calipers on the wheel are brake and emergency brake. Regen is done in the motor.

Definitely sounds like something loose in the trunk.

What do you mean by the 'regen caliper'? Not aware such a thing exists.

It's a compound noise. I do not have things rattling around. And it has nothing to do with the motion of the vehicle. It's the transfer of energy that causes the sound. It is unmistakably mechanical.

If it was an ICE vehicle, I would suspect the transmission or drive train. The sound is much like u joint or axel wear.

It's a compound noise. I do not have things rattling around. And it has nothing to do with the motion of the vehicle. It's the transfer of energy that causes the sound. It is unmistakably mechanical.

If it was an ICE vehicle, I would suspect the transmission or drive train. The sound is much like u joint or axel wear.

Sounds like the service center forgot to re-tighten something. Take it back.

...maybe parking brake not fully releasing?

I suggest taking dead bodies out of your trunk or frunk every 500 miles, regardless of whether you wrapped/sealed them or not. I find this decreases thunk noises when breaking or accelerating, especially if you have many smaller pieces for convenience.

since you're into breaking instead of breaking, it could be parts of the car that you broke.

Doh. typo: "breaking instead of braking"

I'm not sure witch error you where tying to correct. They're is obviously not nothing wrong or anything. Anyways, gotta go bleach the garage ellipsis.

Assuming your 'loaded 85' is not a P?

"braking or accelerating".

@jinglehyme, I have the exact same issue in my car - and have been having it from about 900 miles on the odometer ..

@Brian H, the problem is especially pronounced in my case while braking .. actually while regen braking kicks in I believe as I dont even have to press the brake .. just take the leg off the pedal and there is thumping sound. During acceleration too (gentle acceleration as in stop and go traffic) the problem persists.

I notice it most in stop and go traffic when things are quiet, and I frequently have to take my leg off the accelerator often to ease up.

I'm planning to turn off regen, enable creep and try to see if the problem still persists as that will help narrow systems down may be ..

@jinglehyme and @tesown, at least one person found a bumper that was not screwed down tight. See this thread or this photo.

Could that explain it? Ask Service to check for that.

@ Bob W, will do. The noise seems more like a dull thud rather than a bumper noise .. but good to keep all possibilities on the table.

Sorry to keep beating this idea to death. I know you said you don't have anything rolling around in the trunk. Might you have something rolling around in the frunk? Sometimes it's difficult to discern whether a thunk is really coming from the front or the back, especially if you've mentally associated it with the drivetrain.

@Schlermie, Thanks and yes, the Frunk is free of anything. In fact, I went through the entire car and removed everything from it and tested when I first noticed this.

The sound still persists .. I took a tech out on a ride and he said some amount of that sound may be normal.

However, I have not been able to duplicate it on the other MSs that I have driven.

From the responses here, it appears that others don't hear it either except the OP. So it sounds like this is happening in only a fraction of the cars.

I didn't realize how old this thread was. So what was the answer?

i posted a similar thread earlier. Same issue. My car is in service now for this. they said that there was some slack in the gearbox so they replaced the drive unit (which apparently consists of the motor and the gearbox). i will update again when i get the car back.

he said that this should also fix the low/faint hum that was starting to arise (for me that may or may not be the same 65 mph hum that is discussed in other forum posts, i didn't really have that big an issue).

Edmunds reported a similar sounding problem in their long-term review. They have videos with the sound (for comparison) at

Tesla repaired it by replacing the entire drive unit, as described at

I have a not-very-loud low-speed thunk when taking my foot off of or putting it back onto the throttle (torque direction reversal) that I suspect is backlash in the drivetrain (shaft coupling or gearbox).

Most Tesla owners are total fans, and I think the fundamentals of the car are great - but I have had quite a few issues in my first 18,000 miles. The funny thing, is that as Tesla owners and somewhat early adopters we are very forgiving of these items - especially when Tesla deals with them quickly and without argument. If I had this number of issues with a new Honda or Toyota at a third of the price, i would not be as forgiving!

Call Tesla Service to schedule an appointment. Why put this on the forum and not private?

Mine P85 has developed the exact symptoms you described. A dull thunk at low speeds under light braking acceleration. And a bit of hum even at 40, but worse at 70. Service scheduled for Monday.

One dude found a loose basketball in the trunk. ;)

Do you hear the "thunk" every time you cross zero regen point (drawing power from or providing power to the battery)? Very easy to check, just look at the regen display and see if you can hear the noise whenever you cross zero regen (Plus to Minus, vice versa). Took me awhile to notice the relationship. I have an appt on Tuesday for repair. I was assured that the sound is NOT normal.

I had a thunk noise in the back that would happen every time I would accelerate off a green light or abruptly let go of the gas pedal.

Took it to service and they removed and replaced the drive unit. Clunk gone.

I have started having the same problem on my brand new "replacement" car... just under 500 miles and 7th day!

I'd assume drive train replacement is a major issue. is that right?

Hu'd a thunk?

X Deutschland Site Besuchen