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Old 10-06-2012, 09:51 PM   #343
tinkwithanr
Registered User
 
Join Date: Oct 2006
Location: Springfield OH
Posts: 726
My Ride: '00 323i + '75 2002
I was originally planning to work on the removable front clip today, but some other parts came in the mail so I shifted gears. What did I get you may ask?


A Class 2 trailer hitch and receiver of course!




As any of you that track your car know, normally you want to take spare tires, tools, jacks etc with you. Adding that to the fact that I want to be able to use the car on trips and vacations, the ability to haul a small trailer makes it much more practical. The Class 2 set up is rated for 3,500 gross trailer weight and 300 lbs tongue weight, which will be plenty for anything I ever need to do.


One of the biggest challenges with the hitch was figuring out how to package it with the center exit exhaust in the rear. Originally I was planning to have a fixture for the receiver that would bolt up to the underneath of the trunk frame. While this would have worked, the fixture would have been VERY heavy and a pain to store when not in use. Also the packaging of the exhaust around the fixture would have been difficult, leading to the receiver being very low or very far from the rear edge of the body. Luckily I was already building up a new trunk frame, which gave me a better option.

The first step was to clean up my bumper brackets. This is how the came on the bumper:




Then after a quick trip to the sand blaster:





They still aren't that pretty, but for now they are rust free. After cleaning those I moved on to cutting the receiver to length. I forgot to take pictures while fitting it in place, but here it is tacked in place.





Here you can see the clearance between the body and the locking pin. It's tight, but shouldn't rub on the paint when installed.





Next up was to add the safety chain bars. When towing, the safety chains is used as a last resort in case the ball or hitch fail completely. It should keep the trailer from completely detaching until you can pull off to the side of the road.





With those in place, it was time to reinforce the connections on the inside of the trunk. The picture below shows the receiver, the inner trunk frame, and a strengthening bar on top of both. The receiver is butted up against the trunk frame (you can't really see it, it's in the shadowed area underneath the top tube). The strengthening bar is to help keep the receiver from bending away from the trunk frame.All of these connections were welded fully around to ensure they won't fail.





Then I added another bar across the entire back of the trunk. This is to help keep the trunk frame tube from twisting in the center due to the moment from the tongue weight. The upper tube was notched to fit around the previously shown top brace. It will be stitch welded on both sides across the back of the trunk. The rear portion of the roll cage will tie into the far ends of this upper tube as well.





Here's a close up showing the notched area. Again, all edges are/will be fully welded.






Now why did I need to clean up the bumper brackets for this little project you may wonder? Simple, so that I could ensure the entire hitch assembly would fit behind the stock bumper.


What hitch???





View from the bottom, it was very tight packaging. (For reference, the bottom edge of the bumper is in the top of the picture.)





And this is waiting for me tomorrow:




A partial sheet of 11ga and anew sheet of 18ga sheet metal for the front end work.




Thanks for looking!
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Tinker Engineering - 2014

Mica - 2000 BMW 323i - The one that started it all
Fiona - 1975 BMW 2002 - The Definition of Project Creep
Heidi - 1988 BMW M5 - The piece of BMW history
Silvia - 2013 Subaru WRX - Stock, for now
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