The first major modification we had done to our Tesla– and one of the first reviews I did for Teslarati– was the installation of our Torklift EcoHitch. It was a huge opportunity to get functionality we wanted but I was very nervous about the installation process and, three years later, I’ve discovered my concerns were justified.

Our Tesla made it over three years without a blemish, but this summer an inattentive minivan driver somehow missed the 3 foot long brake light and rammed our rear bumper. Fortunately, no one was hurt and we were somewhat heartened to see that the damage appeared to be superficial and the car was still usable.

Body by Cochran, our local Tesla-approved body shop, had been working on my car for only a day or so when I got some bad news. I noticed earlier in the summer that when I pulled the hitch cover out it was rusty and hard to remove. Since the experts at Cochran would be removing the bumper anyway, I asked them to poke around and let me know what the condition of the hitch was like. I had been recently working under my old Subaru and after eyeballing the Titanic-level rust on its hitch, the cogs in my brain were turning… wondering if the hitch on the Tesla would be better protected hidden behind all those underbody shrouds and the bumper itself.

The pictures sent from Cochran were disturbing. At first the shock of all the rust was concern enough, but I couldn’t figure out why the finish on the hitch was so badly disintegrated. It was only three years old, installed with maniacal attention to detail and all the instructions were followed to the letter and then some. Yet there was no refuting the pictures and the Cochran techs agreed that the failure of the finish was troubling.

I could understand the rust on my old Subaru’s hitch. Like most ICE vehicles, it’s slung under the rear bumper and it’s completely exposed to the elements churned up by the winter roads. Not a single bit of it is protected. Debris and road grit impact the paint, the paint is compromised and slowly but surely, rust takes hold and soon coats the entire assembly. But on the Tesla, the Torklift Ecohitch is completely encased by the bumper and I even had the optional cover on to seal it the rest of the way. Nothing EVER touches the hitch as it is completely protected by various aero shields and the bumper itself.

Even more troubling, the experts at Body by Cochran expressed that they were concerned about what was going on behind the hitch and implored me to have it completely removed and inspected. The surface rust was only part of the problem. As one of the few Tesla-authorized body shops in the region, Cochran’s staff has been educated in the unique problems with restoring crunched Teslas, namely: galvanic corrosion. I didn’t hesitate. Take it all off, baby!

You don’t have to be a metallurgy expert to understand the potential insidiousness of galvanic corrosion. Essentially, two dissimilar metals will have different electrode potentials. These potentials result in one of the metals corroding the other, much like rust, but it can happen without any other outside elements. As the ions migrate from one metal to the other, the corrosion can be aggressive and catastrophic. It’s the basic principle behind the anode rods in your hot water heater, except on the Tesla nothing is sacrificial and certainly not the aluminum structure of the car itself!

Keeping steel and aluminum separate is– no exaggeration– a full-time job. When I picked up the car, the Cochran staff walked me through their shop and explained to me how they have separate work areas and tools for aluminum parts. There are even large curtains to cordon off areas of the shop because even sanded metal grit can get airborne and into the structures and cause problems later. It’s an obsessive nightmare trying to work around all the weird metallurgy, but just another day at the office for these guys.

When the steel Torklift Ecohitch was first installed, it was separated from the aluminum structure of the Tesla by its coating. As the coating failed, the steel began to make a direct contact to the aluminum and it was eating away at the frame of the Tesla. The brownish-red rust of steel is then complimented by the white-grey ash of the galvanic corrosion. Warning! These pictures are a little disturbing (at least to me):

This was all done independent of the rust on the rest of the hitch and in a place completely obscured without removing the entire rear bumper, the rear crash bar and uninstalling the hitch.

For the past three years, we’d been garaging our car and pampering it with hand washes… but underneath a silent killer was consuming the rear bumper structure behind the hitch, and were it not for this accident repair we would never have known until… Well, I’m not even sure of all the ways it could have manifested.

Having seen the pictures, I was almost a little grateful that the car was hit. Now the condition was known and caught soon enough to be stopped. Even better, it wasn’t just me blindly trying to figure it out in my garage, but I was in the hands of Tesla-reconstruction experts. They knew all the procedures and had all the right tools and expertise to restore the car and preserve our ability to use the hitch for our bike rack and protect the car from further damage. The Tesla’s ability to haul a family’s worth of bikes, without heavy lifting, was something I didn’t want to lose.

As luck would have it, we realized the seriousness of the hitch about the same time Cochran discovered Tesla had sent the wrong wiring harness for my new rear bumper. There was a production change made at some point that moved the parking sensors very slightly farther around the bumper. If you didn’t know it was different, I bet you’d never spot the difference– we sure didn’t! Anyway, Tesla had made the change but still managed to send the wrong harness and it couldn’t be adapted. While Serena waited, the Cochran team re-engineered the Torklift Ecohitch installation process.

They scraped down and cleaned up the entirety of the hitch, including every single bolt. All the parts were given a new durable coat of underbody paint.

The inside of the hitch bar was open and, unsure of how deep paint would penetrate, Cochran even sprayed a generous coating of body-sealing wax to keep it from rusting inside too.

The rear of the Tesla was also cleaned up. The rear panel was restored and the entire back side of the frame was repainted as well.

Hardware that was too far gone was replaced with new pieces and they created insulators to keep the hitch from ever touching the body again.

Insulating the bolts wasn’t enough, they also had to isolate the hitch mounting panels. They used a toolbox-lining type material to fabricate large pads to sandwich between the hitch and the rear of the Tesla. In the event the new paint ever wore off, there would still be a physical barrier between the two types of metal.

The good folks at Cochran even resprayed the backside of the steel Tesla bumper crash bar and the hitch’s cover, which had first tipped me off that something was going on in the dark insides of my bumper.

I did reach out to Torklift to see if there was any response or interest in this issue. Cochran had graciously waived most of the charges because my car was already apart for the collision repair, but it seemed reasonable to see if Torklift was willing to help out with what was left. They eventually responded it was their opinion that, essentially, “these things happen.” I was given a one-time offer to remove my hitch, ship it to Washington state (where Torklift is based) and they would repaint it and send it back for me to reinstall, with return shipping at my expense as well.

The initial response from Torklift was disappointing. The market rate to uninstall and reinstall the hitch would be about $300-400 each. The transit/repainting time would mean that, in addition to the $600-800 expense to mess with the hitch, I’d have to schedule two separate trips to a shop to have that work done. Add in the unknown costs to pack and ship a 40-pound chunk of steel across the country, TWICE. And for what? Based on the information I had, it seemed to be a promise of re-coating the hitch in the same finish that had failed and caused all this galvanic corrosion in the first place. Hardly a solution. They offered no alternative mounting instructions or showed any interest in further isolating their steel hitch from the aluminum structure of the Tesla, though it is possible that they did not understand the nature of the corrosion at that time.

So let this be a warning to any Tesla owner who has installed the Torklift Ecohitch. Your experience may vary, but there’s at least some chance that it is quietly eating your Tesla alive in the dark forgotten recesses of your car… completely out of your ability to casually inspect it.

If you’re contemplating a Torklift for your S, you’d be wise to work above and beyond the installation instructions and find a solution with your installer that will keep the hitch isolated from the structure of the car long-term. While it remains the best option for adding a hitch to a Model S (which is why I chose to rehab mine rather than be without it), make sure you understand the implications of “just following the instructions.” Buyer beware.

UPDATE: After this review was posted, Torklift investigated the problems described and is changing their product as a result. You can find their full response in the comments below.