[T3] Type 1 to type 3 tow bar adpter

[Jim Adney]

Dennis,

Thanks for the video; now I see how your attachment was made to work.

A couple years ago, Gary Forsmo and a friend made up a fixture so 
that he could tow his Type 3 behind his RV coach. I helped them with 
the design and the work and it seemed to work quite well, although it 
was designed to work strictly with the towbar that also worked with 
his Honda, so it wasn't something that you could have used.

About a year later, and after towing that car to the NY Invasion, 
Gary's front axle beam suffered a rust breakdown that was unrelated 
to the towing but required replacement of the front axle beam. When I 
removed the beam I wanted to harvest as much of the old internal 
parts as possible, so this meant bandsawing the old beam into little 
pieces.

What I found was enlightening. We had similar U-bolts over the bottom 
section of the beam, but with better spreading of the U-bolt forces. 
Even with that spreading, the box section of the axle beam had 
collapsed as much as 1/4" under where one of the U-bolts rested. 
While this didn't affect the functioning of the axle beam or the tow 
bar, it pointed out that we were expecting too much strength from 
that steel. It just wasn't designed to be strong in that direction.

I gave Gary the cut cross section of the axle beam that shows the 
crushing. If he still has it, perhaps he can post photos somewhere.

In your case, you're also asking the lower pinch weld to take all the 
force of towing. I doubt if it will hold up. Keep in mind that the 
metal there is probably completely soft, made to be pressed into the 
2 halves of the axle beam body. Plus IIRC the pinch weld isn't welded 
with a continuous weld, so you're likely to pop the spot welds.

One more thing: on Gary's car the left pan horn that comes forward to 
support the axle beam appears to have been bent slightly upward. We 
don't know if this is new or if it was long term, perhaps due to rust 
weakening. It's possible, however, that it was caused by the force of 
towing, which was, like your design, applied in a line below the 
support horns, so the towing force would have applied a torque to the 
axle beam and support horns.  

Sorry to be a wet blanket, but I think you might want to know about 
these potential problems before you start your testing.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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