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Front Driver's Steering Knuckle FRACTURED while driving at 55mph [Video]

WASD

Member
Apr 11, 2019
185
119
Culver City
It would be the height sensor, not the speed sensor. The aftermarket fools the car into thinking it's higher and allows a lower drop... which means less cushion to the suspension and more chance of damage.

The change in height alone wont put more stress on the suspension components, the car weighs the same as before. What could possibly cause damage is constantly bottoming out on the bump stops inside the shocks/dampers which would put more force on the knuckle where the shock is seated. Driving around normally with the lowered suspension should not cause damage like this.
 

duncan

Member
Jul 4, 2019
14
15
East Gore
All of the arguments are a bit moot
Careful inspection of the actual broken part will reveal it it was a casting flaw or an overload failure
With the safety margins usually built in to those parts I would be very surprised if an inspection did not reveal a casting issue
 
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WASD

Member
Apr 11, 2019
185
119
Culver City
All of the arguments are a bit moot
Careful inspection of the actual broken part will reveal it it was a casting flaw or an overload failure
With the safety margins usually built in to those parts I would be very surprised if an inspection did not reveal a casting issue

I'd rather point out misinformation than let it stand and influence people negatively. I don't think it's moot at all.
 
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FloridaHeli

New Member
Feb 21, 2020
3
1
Jacksonville, Fl
Driving on the Expressway, and a huge BANG violently shook the car, as if I ran over a huge pothole, knocking my dashcam off its suction mount. Luckily I was able to keep it under control and pulled it to the shoulder. I get out and see the left side of my car is slammed to the ground, and the fender is riding on the tire.

I limp it to a safer spot in a nearby parking lot, and take a look. The Steering Knuckle Casting is Fractured at the bottom of the air spring! Tesla Roadside says they see nothing remotely wrong with my car, so I'll need to pay for the Tow myself.

I haven't heard of this before, and it doesn't seem common. I'm assuming a casting defect caused a crack that propagated into a complete fracture. Luckily my dashcam shows that this wasn't caused by hitting anything, as I'm sure that's the likely reason SC would give for a casting to fracture like that.

35k mi, 2016 P90D

Dashcam Video:

Please supply an update when you can on TESLA’s response to this and if you get reimbursed for the tow. Good luck.

PeRpYsS.jpg

Yisw7dK.jpg

Puc2Xrp.jpg
 

mongo

Well-Known Member
May 3, 2017
12,865
37,840
Michigan
All of the arguments are a bit moot
Careful inspection of the actual broken part will reveal it it was a casting flaw or an overload failure
With the safety margins usually built in to those parts I would be very surprised if an inspection did not reveal a casting issue
Right, an overload failure because the suspension probably bottomed out, thus little to no give and much higher forces imparted on the assembly.

Force imparted:
Normal: spring rate plus inertia of assembly.
Overly lowered: inertia of a significant percentage of the car.

@HankLloydRight , it dies seems slightly off, but I'm more inclined to blame it on video/ audio synchronization rather than having a failure just before a seam/ linear pothole in the road. 60 mph = 88 feet per second, if the camera is 30fps, that is 3 feet per frame so a single frame lag due to camera sampling delay or compression would cause that offset (assuming they didn't resync the audio).
Looks nasty:
SmartSelect_20200711-094706_Firefox.jpg
 

ram1901

Member
Feb 8, 2017
62
59
Delaware
I'm guessing you'll be filing a report with NHTSA?
Why??? The car was being operated in a setting lower than specs using a third party system. Why do people immediately want to blame Tesla. That expansion joint was the final straw. The system was likely being stressed for months. The fact it didn't fail earlier shows the strength of that connection under adverse conditions.
 

vanzandtj

Member
May 10, 2019
51
29
Nashua NH
Driving on the Expressway, and a huge BANG violently shook the car, as if I ran over a huge pothole, knocking my dashcam off its suction mount. Luckily I was able to keep it under control and pulled it to the shoulder. I get out and see the left side of my car is slammed to the ground, and the fender is riding on the tire.

I limp it to a safer spot in a nearby parking lot, and take a look. The Steering Knuckle Casting is Fractured at the bottom of the air spring! Tesla Roadside says they see nothing remotely wrong with my car, so I'll need to pay for the Tow myself.

I haven't heard of this before, and it doesn't seem common. I'm assuming a casting defect caused a crack that propagated into a complete fracture. Luckily my dashcam shows that this wasn't caused by hitting anything, as I'm sure that's the likely reason SC would give for a casting to fracture like that.

35k mi, 2016 P90D

Dashcam Video:

PeRpYsS.jpg
If there was an initial crack that grew gradually, I'd expect the older part of the crack to be a different color.
In this photo, it looks to me like the newly exposed surface of the casting is uniformly white. That suggests a sudden break. More magnification might tell a different story. It could still be a defective casting. I'm guessing someone at Tesla will be inspecting the broken pieces very closely.
 
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serendipitous

Member
Sep 10, 2019
336
493
Maryland, USA
We really just need to address the height question. Is your rear wheel in that photo representative of your normal ride height? If so, 100% the fault of the bizarrely low aftermarket suspension turnbuckles that somehow neither you nor Tesla noticed were out of spec.
 

George Marley

Banned
Jan 12, 2020
73
59
Kansas
I'm just wondering why Tesla doesn't fit rubber bump stops on the suspension.
All it takes is a pinhole air-leak or a faulty compressor and everything turns to poop!


Air Suspension failure with very unpleasant results
Submitted by DBlueS85 on Thu, 2015-07-30 12:25
First the good part: Tesla 1-800 roadside folks were very good, the tow-truck driver was very good, and the service center was very good in repairing my Tesla in one day and then delivering it back in the evening. All very good, and I am enjoying the car again.

Now for the bad part: The right front air strut failed due to a leak which caused the whole front of the car to drop so much that the wheels were rubbing against the inside of the wheel well, and the front of the car was rubbing on the ground. The car became absolutely not drivable. Luckily I was parked when this happened. The tow truck driver could only do inch-by-inch turns to orient the car to face the tow truck, and then had to move it up again inch-by-inch using wooden blocks just so the wheel well and the bottom would not get damaged.

Why doesn’t Tesla air-suspension design incorporate some sort of a stopper to stop the car from going lower than the lowest functional air-suspension setting? The service center tech had the same idea!!!! At least it would be drivable when the system failed. I am very concerned how the car would handle if this air suspension failure occurred while driving 70 mph.
 
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sorka

Well-Known Member
Feb 28, 2015
7,618
5,645
Merced, CA
Actually it looks like it happened right as you hit a joint in the freeway at 4 seconds in to your video. It doesn't look like that joint has a big hole in it, but it looks like you were still completing your lane change so the wheels might have been over a section of that joint that isn't the normal travel path.

Not that that should change anything, unless it is a major hole. (In which case the state might be responsible for repairs.)

It's not only not a dip but a contraction joint (like a sharp speed bump). It's exactly the kind of thing that I slow down to 30 MPH with my emergency blinkers on to crawl over otherwise all my wheels would have fallen off by now :)

Tesla raised the height of the S in 2014 by an inch to mitigate battery strikes. I lowered my car back down an inch with longer sensor links. It's not the sensors that are replaced but the link from the upper control arm pivot attachment to the actual sensor arm.

The car is not any lower than it would have been in 2014 with stock links by the look of it from the pictures.
 

sorka

Well-Known Member
Feb 28, 2015
7,618
5,645
Merced, CA
If you watch closely, the steering knuckle breaks a fraction of a second before he gets to the road joint. It's very close, but you can hear the sound just as the road joint disappears under the car and before the wheels would have hit it.

Don't read anything into video/audio sync issues. I'm sure it broke as result of hitting the contraction joint.
 

sorka

Well-Known Member
Feb 28, 2015
7,618
5,645
Merced, CA
OK, I take it back. The third post picture is the height I height I thought I was looking at. The OP's picture shows a car so low it would be bottoming out. Do you have a picture of your car set to normal or low before this happened?
 

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