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Towing with a 1er

In 2016, after camping at the Alvord Desert in Oregon, I decided that I was done sleeping in a tiny tent on the ground. Years ago, I used to own a tent trailer, but ended up getting rid of it because it was too big and I no longer had a vehicle that could tow it. A friend of mine suggested looking at teardrop trailers. They’re just the right size and light enough that it could be towed by my car, a BMW 135i — once properly equipped.

I started to do a lot of research on the 1er’s towing capacity and the best options for aftermarket tow hardware. The US models of these cars do not have any factory tow options, but the European versions do: The Westfalia Detachable Towbar sold by pfjones (#303323). It is OEM equipment and supports all E82 1-series convertable, coupe, and hatchback models. Even though the website specifically excludes the 135i, it still fit perfectly with no bumper cuts or other modifications needed. The towbar is rated for 3000 lbs of towing capacity with 198 lbs of tongue weight. When not in use, the tow bar neck completely detaches and, to the casual observer, you can’t even tell that this car is equipped to tow. The electrics kit provides a European 13-pin socket and a K-CAN lighting module. No coding is necessary — once the lighting module detects that a trailer is connected, it automatically sends the correct CAN packets inform the other ECUs that the car is now towing. This means the rear park distance control sensors are disabled (no annoying beeps when backing up with the trailer), the car’s own reverse lights are disabled to prevent glare and reflections in the rear window, trailer bulbs are monitored (and any burnt out bulbs are reported in the instrument cluster), and the dynamic stability control system knows to expect different handling characteristics.

The towbar came with Ikea-like language-neutral instructions that, while fairly difficult to decipher due to several models of cars depicted in a single document, were rather straightforward. Basically, the work consisted of the following: remove all the rear-interior trim to gain access to the tail lights assembly and electrical connections, remove the rear tail lights, remove the bumper cover, remove the factory bumper, install the new tow bar in its place, tighten down the bolts to proper torque specifications, wire up the lighting module, and reassemble everything.

It couldn’t be easier!

Except when mistakes are made and instructions get lost in translation:

Brian: “Eric, it says to tighten the bolts to 80 Nm”.

Eric: “Okay, I’ll have to get my bigger torque wrench!”

Fast forward to Eric struggling to wrench on one of the bolts that just wouldn’t seem to tighten down.

Eric: “You said 180, right?”

Brian: “No. 80 Nm.”

Uh oh.

Over-torqued Bolt

As it turns out, when you over-tighten by 100 Nm, every single bolt starts to deform and pull out from its head. If you’re lucky, you feel this so you know right away that there’s an issue. If you’re not so lucky, I guess you would risk losing your entire bumper and trailer while on the highway. Since the bolts are factory welded to the cars frame, we had to hammer them out and find replacements. Thank you, Ace Hardware of Forest Grove, OR, for stocking bolts that are of the correct size and of the correct grade! Embarrassing trip to the dealership avoided!

With everything put back together, we hooked up a rather heavy tent trailer to test everything out, including the cars handling. You can definitely feel the extra weight back there, but the car handled it quite nicely!

135i Towing Test Drive135i Detachable Towbar

Two weeks later, I purchased a Little Guy Silver Shadow 5×10:

BMW 135i towing a teardrop camper trailer

A perfect match.

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