clunk transitioning from on to off throttle

[cduzz]

There's some sort of lash or slop in the drive train when transitioning from on to off-throttle or off throttle to on-throttle.

The car's an early 2016 90D with air suspension with 88k miles

The car's still under the older style 4 year bumper to bumper warranty for a another couple months (got it in june 2019)

Any thoughts as to what this might be?

 

[Aggmeister2010]

Got a recording of the sound? How loud is it? coming from the front or rear?

 

[NewbyMaybe]

Check the rear drive speed sensor for moisture before the warranty expires. There's a YouTube video, any mechanic or diy can do it.

 

[cduzz]

Check the rear drive speed sensor for moisture before the warranty expires. There's a YouTube video, any mechanic or diy can do it.

I thought the rear drive moisture problems were mostly the P models with the big rear drive; my car has the smaller drive unit.

 

[cduzz]

There isn't an audible sound when transitioning; it just feels like there's slop / lash somewhere in the drive system that clunks when transitioning from one load pattern to the reverse of it.

Sometimes it's quite noticeable but more often than not consistent; it's easier to reproduce if on/off throttle while going 15-30MPH.

My suspicion is that there's something loose / worn that shifts under different loads, and that it'll get worse as "it gets wallered out" as it hammers back and forth from loads.

 

[NewbyMaybe]

You have a large rear drive unit.

 

[Aggmeister2010]

There isn't an audible sound when transitioning; it just feels like there's slop / lash somewhere in the drive system that clunks when transitioning from one load pattern to the reverse of it.

Sometimes it's quite noticeable but more often than not consistent; it's easier to reproduce if on/off throttle while going 15-30MPH.

My suspicion is that there's something loose / worn that shifts under different loads, and that it'll get worse as "it gets wallered out" as it hammers back and forth from loads.

I know the experience you’re talking about. If you just drop off the pedal, there is some “slop” type of feel as the motor transitions from providing power to generating power. I have it on my P90D as well. If you feel yours is excessive, since you’re on warranty, why not set up an appointment to have it checked out?

I hate to push the “take it to the dealer” message, but this may well be a normal thing and the SC can tell you that.

 

[snorp]

I had this on my 2020 MX. I would describe my issue exactly as you described yours. Tesla replaced the rear drive unit under warranty after much back and forth and that mostly fixed it. It was really bad under 10 mph if I quickly tapped the accelerator.

 

[cduzz]

You have a large rear drive unit.

Really? It's a 90D (not S90D) -- the car itself reports "induction small" for rear motor.

 

[Kaveman]

Check the mounts where the Drive Unit attaches to the carrier/frame. There are tabs that can snap off.
Something to check
Kaveman

 

[NewbyMaybe]

Thanks for the correction.

 

[snorp]

Something to check

How do I check this? Is there an easy or preferred way to inspect this? Google provided no answers.

 

[TLLMRRJ]

I hate to push the “take it to the dealer” message, but this may well be a normal thing and the SC can tell you that.

Yes, Tesla SC's have become top experts in telling you it's a "normal thing."

 

[Kaveman]

To check if the mount is broken you'll need to look at where the drive unit bolts to the cradle. Backside of the drive unit. The rear plastic cover may need to be removed to see this. Another thing that can cause this "clunk" is the splines on the driveshafts that go through the outer hubs. They need to be Lubed (Ask me how I know). Look on you tube, there are a few vids explaining this.
Kaveman