Check Your Nuts! Found Assembly Error During Hitch Install

Today I undertook the installation of a Torklift trailer hitch on my new Model S and encountered a scary situation. The Torklift hitch is a custom designed hitch for the Model S and comes with detailed instructions on how to remove the rear bodywork, bottom panels, and bumper crossbars to install the hitch receiver. It installs without any drilling, using existing bolts and nus that are part of the Tesla bumper system. It is a great piece and will allow us to use a bicycle carrier with nothing touching the car.

Installation is quite complex, and for most people would be a job for a body shop. However, we have a lift in our barn and all the needed tools, so I tackled it myself. All went well until I removed the bumper cover. Immediately inside the bumper cover is a second stamped steel bumper cross member that is attached with eight nuts to studs that protrude from the aluminum body. This steel cross member is actually a cover for an extruded aluminum cross member that is the main structural element inside the rear bumper. The instructions are to remove the eight nuts holdng the steel cross member with a 17mm socket wrench, then remove eight more nuts that hold on the aluminum crossbar, using a 15mm socket wrench. The trailer hitch is then mounted behind (forward on the car) both crossbars using the original nuts to hold all three crosspieces (including the new hitch) in place.

Imagine my shock when I saw the following pictures (I hope these links work this is my first try at embedding links on the forum). When I pulled the plastic bumper cover away, it was immediately obvious that Tesla had at least one serious quality control issue when assembling my car. Three of the four nuts holding the right side of the steel bumper crossmember were barely threaded onto their respective studs. They were not even hand tight, but very obviously just started onto the studs and far away fom being seated. The fourth nut was properly torqued to 40 ft. lbs. (the torque recommended in the hitch instructions).

If I had not seen this myself I might not have believed it. It was obvious, and in my opinion, the bumper cover installer would have had difficulty missing the loose nuts left behind by the cross member installer. I do not know if that function is robotic, but doubt it. It is serendipitous that these loose nuts are three of the very fitments that I was going to be removing anyway to position the hitch assembly.

This is disturbing on several fronts. How many people with ths condition would uncover it? The loose nuts are fully enclosed in the bumper cavity and cannot be seen. I presume that only a small fraction of Model S owners will install hitches. It is a big job, and requires removing dozens of screws, the entire rear body panel system, carpets, hatch seal, interior panels, rear key sensor etc. Very few people will ever see these nuts in their cars, and they cannot be inpected without hours of surgery to get the external panels out of the way. These bolts are part of the rear crash protection system and are critical to safety. I presume that this means that our car did not meet its safety design specifications, and we never would have known if it were not for my home wrenching project.

Lastly, if assembly quality is this haphazard, I wonder what else isn't bolted tight where it cannot be seen? Part of me wants to ask TM to do a thorough build-level inspection, removing all interior and exterior panels to ensure everything is properly tightened and torqued. Perhaps this is an isolated assemby error, but I worry that it means smething more fundamental - that in the rush to meet its production objectives, TM is having quality issues on the assembly line. I love my car, but it isn't going to be quite the same after this experience.

Links to detailed pictures follow.

Just a thought. Number of people who have disassembled their car to this extent: Probably one. Number of people finding loose bumper nuts: Also one. Therefore failure rate is 100%

Really, what are the odds that the only car to have loose nuts just happened to be the one disassembled?

@Barryfinn, I think everybody on this thread agrees that inspections for all delivered cars are warranted, for the rear and front bumper assembles at least. I would also add the bolts and nuts in both suspension assemblies, because they are easy to access and very critical to safety.

The only discussion is the severity of the issue in terms of risk to life. I don't see it as severe, others do. But in the end that's a moot point if we all agree that the inspections should be done regardless. It's certainly not a design issue, which would be harder to fix.

Here is an update on Tesla's response so far.

I called TM Service last Monday and described the problem. They were alarmed and started a case for the car, to escalate it to production and engineering. The service representative requested that I bring in the car for a full inspection, which we scheduled for this coming Staurday on Rockville (a 400-mile round trip). He said they will need the car for a while and will provide a rental. Probably going to be stuck with a Hyundai for a week...

He also asked that I send the pictures in an email, so that TM engineering and production can see exactly what I found, so I sent him this link:

I also started a NHSTA case for this as it is a pretty serious safety issue affecting structural integrity. Interestingly, the NHSTA did not have the Model S in their automobile database yet, but informed me that my case will add it. Apparently my Model S has the distinction of being the first reported safety incident on these cars.

P_Dave, even though I do not see it as a serious structural integrity issue as I noted previously, I think you did the right thing.

Thank you for the update.

PD -- I'm not familiar with the process, but would the NHSTA request a recall by Tesla if your problem is considered a safety issue?

danielccc +1

PD -- Were just the nuts loose for the plastic casing covering the bumper loose or were the nuts securing the actual bumper loose as well? I don't see a picture of the bumper nuts before you pulled off the bumper in your dropbox picture folder. Is there another picture folder I'm not seeing?

I found this video clip on youtube that shows the bumper being pulled off to install a hitch... only reference I could find showing the actual bumper bolts and nuts...

PD this is serious and I'm considering pulling all my interest out of Tesla if what you say is true... you stated the following:

"three of the four nuts holding the right side of the steel bumper crossmember were barely threaded onto their respective studs. They were not even hand tight, but very obviously just started onto the studs and far away fom being seated."

However, from the pictures you've posted, all I see are the bolt and nut assembly for the plastic covering being loose, not the bumper crossmember. You've for some reason left out that picture out and only show the unpainted bumper area without the bumper.

Please clarify if you please...

Steel crossmember... not plastic, sorry. Was the aluminum crossmember loose as well? That's my question.


There are 8 nuts holding the steel crossmember and 8 nuts holding the aluminum extruction underneath it. Both crossmembers have four nuts on each side. Both crossmembers are structural. I am not sure which one is intended to perform which element, bit both are part of the crash crumple zone. All of the 16 studs on which both crossmembers mount are the same size, but the nuts on the stamped steel piece are larger diameter than teh ones fixing the aluminum extruded crossmember. All of the nuts are visible in the two dropbox folders that I posted above.

The plastic bumper cover is cosmetic only, and is held on by a bunch of small metal screws into retaining clips, and some plastic expansion button clips, as well as pressure clips along the edges. All pretty standard auto body assembly techniques. The picture directory links are repeated below. You cannot see all of the detail in the top-level pictures - click on the first picture and a larger slide show will begin, and you can click through the higher resolution versions.

loose bumper nuts pictures:

pictures of entire hitch installation, including inner aluminum crossmember:

extrusion, sorry

So the inner aluminum crossmember was not loose? If that was loose then this problem goes deep into the QC chain and many, many people missed this deficiency.

Just saw a brief interview on CNBC with Elon Musk where he says workers were putting in 70 hour weeks around Christmas in order to make delivery schedules. QC no doubt suffers under those conditions.

Update on the loose bumper nuts - TM had the car for the last week at the Rockville Service Center. It was a positive interaction with TM all around. Lenny Peake, the Service Manager, and Nathan DeBaise, the Service Advisor, kept me apprised of what was going on, and the car was thoroughly gone over.

The front and rear body panels/covers were removed and all bolts and nuts checked for proper torque, as were all suspension parts. Everything was found within specifications, so the conclusion is that this was a one-off assembly anomaly.

According to Rockville staff. the situation was reviewed at corporate all the way up the chain. I have no way to confirm that, but it is logical that this would be of interest to the top people in production and QC.

I picked up the car at Rockville today, and a couple due bill items were resolved - Nathan gave me a new charging cord with proper cover plates, and a charging cord bag (I never knew this was part of the deal, so a nice surprise). He also threw in a couple key fob lanyards (not TM-specific, just something they picked up at the SC for customers.

Nathan also informed me that the parcel shelves are shipping, that TM supposedly received 5,000 and is sending them out now, including extras to the local stores so they can be picked up or sold ad hoc. The HPWC is my only other open item, and they are apparently also shipping in quantity now.

I asked about the status of service contracts and Nathan indicated that he does not know when they will be available. He gave the same response for wireless contracts. He did say that TM has been using different wireless service providers, not just AT&T as some here have indicated.

Lastly, I asked about the rear lid “85” insignia. Nathan indicated that it was a production-line upgrade, and applies only to 2013 cars. I replied that my car is 2013 production, but he said “I don’t know of any plans to slap the numbers on cars that did not come with them.” Those of you who apparently believe that anything new that TM does to the Model S will be retrofitted to your car are in for a surprise – it won’t happen.

After a fast run around DC and over to Annapolis today, I continue to be blown away by how great this car is. I consider the bumper nut saga to be over at this point, probably a symptom of the year-end rush to get cars out, and a lesson learned at the factory.

NHTSA will be thrilled, unless they've been furloughed...

"nickniketown@gm... | MARCH 5, 2013 NEW
Time for a recall."

They wouldn't be a real automaker if they didn't have any recalls! :D

Blue P85 checked at MP service 4wks ago. One nut seated but not torqued correctly, replaced. All others fine.

@_Dave, any hint whether you might have been permitted to purchase and keep the charging cord without the cover plate? That's my only due bill item, and I'd love to keep the current cord (without the plate) as a spare if they'd let me buy it when the replacement arrives.

Barryfinn, failure rate is should not be stated as 100%. Not appripriate to make that assumption with a sample size of 1 out of 5000

How about failure rate of 100% with .0001% confidence interval? I didn't do the math, but as I recall there is a formula for figuring out the probability that the failure rate number is accurate. You have to assume some distribution curve. But yes, with a sample size of one, you have very little confidence in any answer.

Call the "How to Keep an Idiot Entertained" Hotline at 401-285-0696, where we will teach you exactly how to entertain any idiot for at least one minute!

Whoops, Alex beat me :)

That is so age appropriate for nick-nickelodeon. His post already gone...

It's even the right area code. You don't suppose ...

Entertain an idiot, at his home phone.

Excellent, Nick. Thank you for canceling the reservation you never had in the first place. Perhaps your nonexistant brother will sell you his if he gets tired of driving it.

You have been an incredible pest here, and have abused many peoples trust in your integrity, and tried our patience. You've also caused work for the site who spends time hosting your posts and playing whack-a-mole having to remove them.

We all look forward to seeing you again when you don't reserve a model X, and don't reserve a Gen III and come on here to give everyone your google researched opinions.

Looks like Nick evaporated like a popsicle on the hot pavement even before I could say goodbye.

For those that missed his last post, he says he's cancelling because of us.

After all his complaints, the FORUM is what led Nick not Nick to cancel his not a reservation?!

@jbherman - well, that and no door pockets.

Is your mouth frozen up? Did you going below -12 Fahrenheit? I don't understand the sentences you wrote above?

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