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24 November 2006

Custom Trailer Hitch

Please Read:
I constantly get requests for plans/CAD drawings/etc. for the vertical-receiver hitch design. For liability and copyright reasons, I will not provide any plans or drawings. Please do not email me to ask where you can buy a hitch for the A3.

I frequently get emails asking questions that are clearly answered in this article. Please read every word of the article thoroughly. Everything I know about this or any other A3 hitch is in the article. If it's not in the article, I don't know it. Emails asking for plans, where to buy, or anything else already covered in the article will not be answered.



Ever since I first considered had the A3 I wanted a receiver hitch for it. I've had them on various other cars for pulling JetSkis and stuff, but never got around to putting one on my GTI. One problem with owning a hatchback is that everybody expects you to be their truck. I really didn't want to use my new car for that, especially things that could damage the interior, so the ability to pull a small trailer was important. The lack of an available hitch was a strike against the A3 when I was shopping but I decided that, worst case, I'd design my own.

After I got the A3 I started looking into the European hitches that were available for it. The best hitches are made by Westfalia Automotive, and I believe they make the ones that Audi sells in Europe. European receiver hitches are designed quite differently from American ones:

  • Euro-style receivers are vertical, or close to it; not horizontal.

  • A J-shaped bar goes into the receiver, and has the ball on it.

  • The receivers have a much more sophisticated attachment system for the J-bar than the simple pin used in the US.

  • The ball is part of the J-bar, not removeable.

  • All balls are 50mm; by comparison, a US 2-inch ball is 50.8mm.

  • European hitches do not have loops to attach safety-chains, which are required in the US.

  • Most of the European hitches for the A3 take the place of the bumper reinforcement bar.



Here is a drawing of a European ball & J-bar for an A3:



My first thought was to obtain a European hitch and modify it. That proved very difficult - most vendors (including Westfalia) refused to sell to anyone in the US. Some eBay sellers would sell to me, but shipping costs were huge. Just to get a hitch (that I couldn't have used unmodified) would have been around $800, and then I'd have to modify it a lot. I was also really afraid of the wrong item being shipped to me, and being stuck with either an expensive unusuable hunk of steel or a huge return shipping expense.

UPDATE:
www.oempl.us now imports the Westfalia hitch to the US. It is an updated model that DOES include safety-chain loops. They also carry the required replacement valence. The only downsides are that it's expensive and you can't attach a bikerack, but if you want a genuine European-style hitch, it's now available.


So, I began designing one on my own. I had a good plan of what I wanted it to be like, but didn't have the help, or the money, to make it real (my CAD skills are pretty lame). I contacted a major US hitch manufacturer and tried to get them to make a hitch for the A3, but that didn't work out - they needed a car to prototype on, they were too far away to use my car, and I couldn't coordinate getting anyone closer to them to do it.

This summer I got an email from somebody who had just bought an A3, desperately needed a hitch, and had seen one of my hitch-related postings on the AudiWorld forums. Joe and I began collaborating on the design - he's an engineer and drafts metal parts in CAD all the time, so it was a perfect match. We both agreed on the approach, and quickly refined it via email and phone. Once we had the design worked out, I approached the hitch manufacturer again about producing it and provided them CAD drawings of the design. We were to receive the prototypes for testing, and they could then produce our finished design.

It hasn't turned out exactly that way. We received the prototypes, provided feedback, and were convinced that there was nothing in the way of having this great design available to the rest of the A3 community. However.... later we were told that '...the powers above...' in the company had overridden the design, and decided that the concealed vertical receiver would be replaced with a conventional, exposed, horizontal receiver. This completely destroys the design intent of the hitch, and Joe & I do not consider it to be 'our' design that they will produce.

For now, I'm considering this to be one of only 2 custom hitches made from my concept.

  • It has a vertical receiver tube that is completely concealed behind the bumper cover.

  • When the ballmount is removed, no part of the hitch is visible.

  • The safety-chain loops are also concealed above the lower edge of the bumper cover

  • The original bumper reinforcement bar is retained, satisfying SCCA requirements for certain autocross classes.

  • It can be installed by one person with hand tools and a drill in about 1.5 hours.

  • It is compatible with the standard and S-Line bumper valences, and appears to be compatible with the Votex valence.

  • With a 90-degree adapter (which I will have fabricated soon), it's a great way to carry a bike rack or ski carrier.





Before Installation:



Ballmount designed for vertical receiver.



The hitch, as viewed from the rear of the car. The flanges on the end rest on the bumper supports, and the receiver tube points downward.



Assembled ballmount and hitch, with hardware.



The Result:



The tab of plastic between the two underside mounting screws on the bumper cover was trimmed off behind the ridge, and a notch was cut into the bumper cover: 4.5cm wide x 3.5cm deep from the new trimmed edge of the cover. This allows just enough for the receiver, and a gap for reaching up to the pin and safety-chain loops, but is completely unnoticeable unless you stick your head under the bumper.



The ballmount is inserted into the receiver tube vertically....



...and secured with a pin. I use a Master Lock keyed locking recever pin (see below). You can see that there's just enough space to use the keys. The rear edge of the bumper valence will be smoothed and painted as soon as my touch-up paint kit arrives.



The ballmount in place. It will clear the standard, S-Line and Votex valences, as far as I can tell.



Interchangeable Ball System & Locking Pins:



I like this ball system better than any other I've seen. It's stainless steel, and the 1-7/8" and 2" balls can be swapped in under a minute.



The part shown in the centre of this photo bolts down like any other hitch ball does. The ball drops on top of it, and the captive pin holds it in place. When a trailer coupling is attached, it covers the ball so there's no chance of the pin working loose.



This Master Lock set has both a locking receiver pin, and a locking trailer-coupling pin.



It's a keyed-alike kit, so all 4 keys that came with it operate both locks. I keep one key with each of the fobs and the valet key, and one hidden in the car. The key cannot be removed unless it is in the 'locked' position.



The best part of these accessories is that there's a perfect place to keep them....



More Photos of the Installation Process:


Click For Photos of the Hitch Installation


Here are my co-designer's photos right after he got the first prototype installed, hooked up and test-driven (originally posted on AudiWorld.

For electrical hookup information, see my A3 Trailer Lighting Wiring Instructions.








Update: May 2008



One downside of this design is that I couldn't attach a bikerack without an adapter. I had the design for an adapter all along, but was just slack about getting it made, mostly because I didn't know where to get the welding done. Recently I got a referral to someone who could help with the fabrication, so I went ahead with the project.

I started by ordering a 1-1/4" receiver fabrication part from eTrailer.


The person who did the fabrication for me had the steel shank, and did an excellent job.






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