[Mohre]

My son just had the same issue. The model 3 is being towed to Tesla now. Thank god he was in a parking lot. 52,000 miles. So out of warranty. Purchased in 2018.

 

[Mohre]

 

[tivoboy]

That is just BEAT!… its hard to tell exactly where the fail point is, but it looks as if there is some attach point in the sub frame that this arm attaches to - that is just GONE. I’m going to have to get under the car and check this out before my next 500 mile road trip.

I’d love to hear from others what the FIX is and the parts used - and of course COST.

 

[iChris93]

but it looks as if there is some attach point in the sub frame that this arm attaches to - that is just GONE.

It doesn’t look that way to me. Looks like the bolts backed out.

 

[tivoboy]

It doesn’t look that way to me. Looks like the bolts backed out.

Could be, I see what you mean. I’m surprised though that there wouldn’t be a flat brace/bracket UNDER the control arm bushing. Just to be seated in the U flange there seems easier to mount, but IF bolts break or come loose (there is NO reason those bolts should have come loose) the arm just falls.

 

[Power Surge]

So because this seems to have happened to more than one person, and appears more common on older M3s like my 18, I decided to check mine out on the lift at work the other day.

Happy to report that all my bolts were still nice and tight.

Upon inspection, I can understand why Tesla replaces the front subframe for this repair. There are two bolts for that control arm attachment. One bolt goes into a nut that's external, and spot welded to the subframe. However, the other bolt is encapsulated inside the subframe, covered by a few pieces that all come together right over that nut, making it impossible to inspect from the top or repair. So you'd need to replace the subframe IF the threads on that nut are damaged.

Being an auto tech, if this happened to me, I would just cut a small hole next to where the nut sits to be able to access it, and then use a new nut in place of the damaged one. The new hole would allow the use of a wrench to hold it for tightening down the bolt.

 

[JasonF]

I don't have a lift, so I used a mirror and a bright light to examine the construction of the lower control arm. Mine seems to still be firmly attached!

The inner mounting point for the lower control arm does not look like it's designed to have any force applied to it. It's basically just a lockdown point to stop it from falling down (as pictured in the OP). The center bushing is what is designed to absorb suspension forces.

The two forces that could cause the bolts to come out would be: 1) Vibration, which can be mitigated by thread locker, which I don't see in the OP; and 2) Extreme force, such as collision with an object from beneath, or suspension forces too strong for the center bushing to absorb, or unwanted rotational forces. Remember, any forces transmitted all the way to the inner end of the lower control arm are transmitted directly into the car's frame (there is no bushing at that mounting point), which is neither ideal nor normal.

Out of those two, (1) would not require replacement of the subframe - it would simply require reapplying the bolts with some thread locker. The second of the two, (2) above, would require replacement of the subframe as the bolt holders (basically large nuts welded to the subframe) would no longer align with the lower control arm, and/or would no longer have reliable threads.

It's possible that Tesla can't really tell if (1) or (2) occurred, so they're replacing the subframe as a precaution. But after looking at mine, it seems like the photo in the OP, there are some torn undercovers, the outer control arm bushing seems to have separated (left side of the photo), and the subframe mount does not seem to be aligned in its normal location. Therefore it would be normal for Tesla service to suspect that the subframe encountered some extreme force, and recommend replacement.

 

[Kbecks]

Out of those two, (1) would not require replacement of the subframe - it would simply require reapplying the bolts with some thread locker. The second of the two, (2) above, would require replacement of the subframe as the bolt holders (basically large nuts welded to the subframe) would no longer align with the lower control arm, and/or would no longer have reliable threads.

It's possible that Tesla can't really tell if (1) or (2) occurred, so they're replacing the subframe as a precaution. But after looking at mine, it seems like the photo in the OP, there are some torn undercovers, the outer control arm bushing seems to have separated (left side of the photo), and the subframe mount does not seem to be aligned in its normal location. Therefore it would be normal for Tesla service to suspect that the subframe encountered some extreme force, and recommend replacement.

Actually it's that one of the two nuts for capturing the bolts on that lower control arm are FULLY encased in the subframe weldment. You physically cannot replace the nut if the spot welds which hold it in place break free, which happens to a lot of people (myself included).

But yes it seems the bolts were initially installed without any threadlocker or retention to prevent loosening from vibration over time. The fact they are installed upside down, with an inaccessible spot-welded nut for threads, is also a bit ridiculous. These cars suck for maintenance and reparability, purely optimized for manufacturing to keep costs down.

 

[flygdchman]

Sounds like a known issue.

Model 3 : control arm disengaging

My vehicle, was parked and pulled out of the parking lot on a doing a complete left steering turn, couple of nuts&bolts carrying the vehicle control arm fell to the ground and the entire control arm disengaged out of the shafts. This could have been very fatal, if my family or me were riding the...

teslamotorsclub.com

Recall notice

https://static.nhtsa.gov/odi/rcl/2021/RCLRPT-21V835-2749.PDF

 

[Kbecks]

Recall notice
https://static.nhtsa.gov/odi/rcl/2021/RCLRPT-21V835-2749.PDF

It's a very, very limited recall and many people who have reported the problem were not included in it.

 

[flygdchman]

UPDATE: Does Your Tesla Model 3 Creak Or Pop? Check For Loose Bolts

A Tesla Model 3 owner heard some pops and rattles coming from the suspension and decided to have a look. This was what he found, but what if he didn't?

insideevs.com

 

[flygdchman]

It's a very, very limited recall and many people who have reported the problem were not included in it.

This needs to be raised with NHTSA again then. They have accepted Tesla's definition of the field exposure.

 

[tivoboy]

Count me as one who is more than slightly concerned about this. I’m pretty good with ICE cars and overall vehicular functionality, but I don’t have a jack and don’t really have a way to confidently confirm that this isn’t a current issue or developing issue.

I’d really like Tesla to at least confirm that SOME vehicles should be looked at, either mobile or SCenter appointment and have them either for free verify or for some limited expense verify that this is not a problematic issue.

With some of the clear issues that have occurred, not the least of which is the HWY 1 issue where the car went over the cliff (reportedly due to Driver intent, but I’ve also heard “mechanical issue” I’d like to know that my car while driving isn’t going to lose the ability to properly control one FRONT wheel possibly at an unpredictable point in time.

 

[Klaus-rf]

This is a VERY poor design (IMHO) for a suspension attachment. Here are some pics from the Tesla Model 3 Service Manual and the inward part of the lower arm is attached with two bolts (and associated nuts, apparently not welded when the drawings were published) and those bolts are loaded in single shear with a yuuuge bending force from a very heavy car. They will never be secure.

Not all the other suspension mounting points are mounted in double shear with the suspension attachment between two ears and a thorough bolt / nut (except the ball joints).

 

[flygdchman]

This is a VERY poor design (IMHO) for a suspension attachment. Here are some pics from the Tesla Model 3 Service Manual and the inward part of the lower arm is attached with two bolts (and associated nuts, apparently not welded when the drawings were published) and those bolts are loaded in single shear with a yuuuge bending force from a very heavy car. They will never be secure.

Not all the other suspension mounting points are mounted in double shear with the suspension attachment between two ears and a thorough bolt / nut (except the ball joints).

Does it specify the bolt torque?

 

[Klaus-rf]

Does it specify the bolt torque?

Yes.

106N-m, aka 78.18158782339063 Ft-Lbs.

 

[Kbecks]

This is a VERY poor design (IMHO) for a suspension attachment. Here are some pics from the Tesla Model 3 Service Manual and the inward part of the lower arm is attached with two bolts (and associated nuts, apparently not welded when the drawings were published) and those bolts are loaded in single shear with a yuuuge bending force from a very heavy car. They will never be secure.

Agreed, i've always heard that bolts are just for clamping force and not really intended to take bending. Seems like the in-board side of the arm should have some feature that reacts against the subframe to reduce bending moment on the fasteners themselves. Or something like what MPP did: Solid Front Lower Control Arm Bearings for Tesla Model 3 & Model Y

 

[flygdchman]

Where is the bending load coming from?

 

[JasonF]

Where is the bending load coming from?

The rubber bushing can only take so much twisting force before it passes some of it along to the subframe. It looks like the MPP ones swap that for a very slippery steel and teflon bearing so it doesn't pass as much of the twisting to twisting to the subframe.

 

[flygdchman]

What I was asking is where are the forces that are driving the bending / twisting loads coming from?